MetaWear API Specification

MetaWear API 1.0.0 Specification.

Bluetooth Low Energy

MetaSensors (MetaWears or MetaWear sensors) measure movement (accelerometer, gyroscope, magnetometer, sensor fusion), temperature, air pressure, and present this via the GATT connection.

The Generic Attributes (GATT) is the name of the interface used to connect to Bluetooth LE (Low Energy) devices. The interface has one or more Bluetooth Services, identified by unique ids, that contain Bluetooth Characteristics also identified by ids.

A GATT client (such as your smartphone or laptop) scans for devices that are advertising and connects to a GATT server (a chosen MetaWear device). Once connected, the client discovers the Services and Characteristics of the server. Then, it reads from, writes to, or sets up a connection to receive notifications from the Characteristic.

Here's a brief breakdown:

1. Scanning for Devices: The GATT client (e.g., a smartphone or laptop) scans for nearby BLE devices that are advertising their presence.
2. Connecting to a GATT Server: Once a device (e.g., a MetaWear device) is found, the client can connect to it. The device acts as the GATT server.
3. Discovering Services and Characteristics: After connecting, the GATT client queries the server to discover the available Services and Characteristics. Services are collections of related functionalities, and Characteristics are attributes that contain specific data.
4. Interacting with Characteristics:
5. Reading: The client can read data from a Characteristic.
6. Writing: The client can write data to a Characteristic.
7. Notifications: The client can set up notifications to receive updates from a Characteristic automatically when its value changes.

The BluetoothSIG provides a set of standard UUIDs for Services and Characteristics which the MetaSensors support:

Service UUID	Characteristic UUID	Description	MetaWear Result
180A	2A24	For Model Number	8 (MetaMotionS)
180A	2A19	For Battery Life	1.2
180A	2A25	For Serial Number	055B9E
180A	2A26	For Firmware Revision	1.7.2
180A	2A27	For Hardware Revision	0.1
180A	2A29	For Manufacturer Name	MbientLab Inc

For example, a heart rate sensor will typically use the Bluetooth adopted and standardized Heart Rate Service (UUID: 0x180D) and Heart Rate Measurement Characteristic (UUID: 0x2A37).

However, this is where the standards stop for the MetaWear spec.

MetaWears do not use the standard SIG Services and Characteristics because there are too many sensors on board and there are not enough Services and Characteristics available to support them all. Additionally, standardized Characteristics and Services for data such as “quaternions” do not exist.

Instead, the MetaWear advertises a unique Service and Characteristics that use a custom serial protocol to send commands and receive data.

MetaWear advertises the Service UUID: 326A9000-85CB-9195-D9DD-464CFBBAE75A.

The MetaWear protocol uses the Characteristic UUID: 326A9001-85CB-9195-D9DD-464CFBBAE75A to send commands to the board.

The MetaWear protocol uses the Characteristic UUID: 326A9006-85CB-9195-D9DD-464CFBBAE75A to send responses. The responses may contain ACKs, device information, or sensor data. You must subscribe to this Characteristic.

Name	128-bit UUID	Mode	Length
MetaWear Service	326A9000-85CB-9195-D9DD-464CFBBAE75A
Command Characteristic	326A9001-85CB-9195-D9DD-464CFBBAE75A	Read / Write	20
Notification Characteristic	326A9006-85CB-9195-D9DD-464CFBBAE75A	Read / Notify	20

Modules

Sensors and peripherals on the MetaWear are referred to as Modules.

The following Modules are available:

Module Name	Opcode	Description	State
Switch	0x01	Mechanical button	Active
LED	0x02	Color LED	Active
Accelerometer	0x03	BMI160 or BMI270 acceleration sensor (3D accelerometer)	Active
Temperature	0x04	Thermistor, external, and internal temperature sensor	Active
GPIO	0x05	Analog and digital IOs	Active
Neo Pixel	0x06		Deprecated
iBeacon	0x07		Deprecated
Haptic	0x08	Buzzer driver (for MMS+ or MMRL+)	Active
Data Processor	0x09	Internal math for sensor filter	Active
Event	0x0A	Events such as losing the Bluetooth connection	Active
Logging	0x0B	Start, Stop, download or trigger sensor data logging	Active
Timer	0x0C	Built-in timer (used for delays, counting or debug)	Active
Serial Passthrough	0x0D	I2C bus	Active
ANCS	0x0E		Deprecated
Macro	0x0F	Store commands in the memory	Active
GSR (Conductance)	0x10		Deprecated
Settings	0x11	Bluetooth settings such as device name or TX power	Active
Barometer	0x12	BMP280 pressure sensor	Active
Gyro	0x13	BMI160 or BMI270 rotational (angular velocity) sensor	Active
Ambient Light	0x14		Deprecated
Magnetometer	0x15	BMM150 magnetic field sensor	Active
Humidity	0x16		Deprecated
Color Detection	0x17		Deprecated
Proximity	0x18		Deprecated
Sensor Fusion	0x19	Bosch algorithm for orientation (Quaternion or Euler angles)	Active
Debug	0xFE	Reset device or jump to bootloader	Active

Serial Protocol

Commands to the MetaWear are sent via Writes to the Command Characteristic.

Responses from the MetaWear are received via Notifications from the Notification Characteristic.

Data Encoding

All multi-byte values in the MetaWear serial protocol are encoded in little-endian byte order. This means the least significant byte comes first.

For example, the uint16_t value 0x01F4 (500 in decimal) is sent as [0xF4, 0x01].

The data types used in the protocol are:

Type	Size	Description
uint8_t	1 byte	Unsigned 8-bit integer (0 to 255)
int8_t	1 byte	Signed 8-bit integer (-128 to 127)
uint16_t	2 bytes	Unsigned 16-bit integer, little-endian (0 to 65535)
int16_t	2 bytes	Signed 16-bit integer, little-endian (-32768 to 32767)
uint32_t	4 bytes	Unsigned 32-bit integer, little-endian
int32_t	4 bytes	Signed 32-bit integer, little-endian
float	4 bytes	IEEE 754 single-precision floating-point, little-endian

Bit fields within a byte are packed from the least significant bit (LSB) first. For example, if a byte contains a 2-bit field a and a 3-bit field b, the layout is: bits 0-1 \= a, bits 2-4 \= b, bits 5-7 \= unused.

Module Discovery

When a host connects to a MetaWear for the first time, it should discover which modules are available and their implementations by reading the Module Info register (0x00) from each module opcode.

The discovery process is:

1. Subscribe to the Notification Characteristic (326A9006)
2. For each known module opcode (0x01 through 0x19, and 0xFE), send a read command: [opcode, 0x80] (reading register 0x00)
3. The MetaWear responds with: [opcode, 0x80, impl_id, revision, ...]
4. If a module is not present on the board, the response will indicate an invalid or empty implementation

The Implementation ID identifies which hardware variant is present (e.g., BMI160 vs BMI270 for the accelerometer), and the Revision indicates the firmware revision for that module. Together they determine which registers are available and how data should be interpreted.

Packed Data

Several sensor modules (Accelerometer, Gyroscope, Magnetometer) provide a Packed Data register that sends three consecutive XYZ samples in a single 18-byte notification instead of one 6-byte sample at a time.

The packed format is:

Bytes 0-5	Bytes 6-11	Bytes 12-17
Sample 1	Sample 2	Sample 3
X, Y, Z	X, Y, Z	X, Y, Z

Each sample is three int16_t values (X, Y, Z) in little-endian order. Using packed data reduces BLE overhead by transmitting 3x the data per notification, which is important at high sample rates (200Hz+) where individual notifications cannot keep up.

Command Format

When sending commands or receiving data, the serial protocol format is as follows:

Byte 0	Byte 1	Bytes 2 - 19
Module Opcode	Setting Address	Value

The Opcode refers to the table in the Module section above.
The Address and Value depend on which Module is specifically addressed.

If the command involves reading data once, the Setting Address should be bitwise OR’d with 0x80.

Byte 0	Byte 1 (bits 0-7)	Byte 1 (bit 8)	Bytes 2 - 19
Module Opcode	Setting Address	1 means a one time read0 means a write or notify	Value

For example, when sending the following command bytes to the MetaWear Command Characteristic [0x03, 0x0f, 0x01, 0x00]:

• 0x03 is the Module Opcode for the accelerometer
• 0x0f is the Address for the orientation interrupt enable register, we want to write to it
• 0x01 0x00 is the 2 byte Value that the user wants to write to that register which corresponds to turning it on

The MetaWear will turn on the accelerometer and immediately start sending orientation data to the smartphone or computer.

For example, when sending the following command bytes to the MetaWear Command Characteristic [0x04, 0x81, 0x00]:

• 0x04 is the Module Opcode for the temperature sensor
• 0x01 is the Address for the temperature sensor data (0x81 means we want to read it)
• 0x00 is the 1 byte Value that a user must send to represent which temperature sensor we want to read from (internal, thermistor, external), 0x00 represents the internal sensor

The MetaWear will see the read temperature command and send back the temperature value.

To understand the Addresses and Values, users must refer to the tables in the corresponding Module chapter:

Setting Address	Mode	Wlen	Rlen	Value
The 2 byte Address for the register	The modes supported: R = Readable register W = Writable register N = Notifiable register	Length of Value bytes when writing	Length of Value bytes when reading and notifying	Byte or bit level detail of what the Value means

Let’s revisit the data packet sent to the Command Characteristic in the last example [0x04, 0x81, 0x00]:

• 0x04 is the Module Opcode for the temperature sensor
• 0x81 is the Address for the temperature sensor data register 0x01 OR’d with 0x80 because we want to read it
• 0x00 is the Value that represents the 1 byte index where a value of 1 represents the on-die temperature sensor, 2 means the on-board thermistor, and 3 is a external temperature sensor that can be added to the GPIO pins

The temperature data received from the read above is [0x04, 0x81, 0x00, 0x00, 0x01]:

• 0x04 is the Module Opcode for the temperature sensor
• 0x81 is the Address for the temperature sensor data with a read
• 0x00 0x00 0x01 is the 3 byte Value where the first byte is the index described above and the next 2 bytes int16_t in units of 0.25 C

For example, you may receive the following data: [0x03, 0x11, 0x07] where:

• 0x03 is the Module Opcode for the accelerometer
• 0x11 is the Address for the orientation data register
• 0x07 is the 1 byte Value that represents the FACE_UP_LANDSCAPE_RIGHT orientation

0x01 - Switch Module

The Module Opcode is 0x01.

The MMS and MMRL both have a switch on board that doesn’t have functionality out of the box. The functionality can be programmed so that it can be used in conjunction with the Event Module to start recording data, turn on the LED, etc.

The button has two states:

• Pressed / Down (0x01)
• Unpressed / Up (0x00)

The button is already debounced and stays at value 1 when pressed.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Switch State	0x01	RN	1	1	Byte 0: Switch State (Value \= 0x00 or 0x01)

0x02 - LED Module

The Module Opcode is 0x02.

By default the RGB LED on the MetaSensors turn on when the device is charging. It is green when the device is fully charged and blinks blue when charging (when plugged in).

The LED is programmable and this default can be overwritten. The LED can be turned off using the Stop command, paused using the Pause command, and turned on using the Play command.

Before the LED can be turned on, the Mode should be set to determine how the LED will behave when turned on including color, time on/off, brightness, and so on:

• Mode 0x00: Solid
• Mode 0x01: Blink
• Mode 0x02: Flash

Depending on the Mode, you can create a pattern that determines how bright the blink mode is or how many times to flash the LED.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 1 (uint8_t) Byte 2: Channel Count (uint8_t) Byte 3: Secondary Mode Length (uint8_t)
Play	0x01	RW	1	1	Byte 0: Value 0x00 \= Pause pattern Value 0x01 \= Play pattern Value 0x02 \= Autoplay
Stop	0x02	RW	1	1	Byte 0: Value 0x00 \= Stop pattern Value 0x01 \= Stop and Reset Channels
Mode	0x03	RW	18	18	For a Write: Byte 0: Channel: 0: G, 1: R, 2: B Byte 1: Mode Mode (0x00) "Solid" (no pattern) Mode (0x01) "Blink" pattern: Byte 2: On Intensity (0-31) Byte 3: Off Intensity (0-31) Byte 4-5: Time On (ms) Byte 6-7: Time Period (ms) Byte 8-9: Time Offset (ms) Byte 10: Repeat Count (0-254, 255: Forever) Mode (0x02) "Flash" patter: Byte 2: On Intensity (0-31) Byte 3: Off Intensity (0-31) Byte 4-5: Time Rise (ms) Byte 6-7: Time On (ms) Byte 8-9: Time Fall (ms) Byte 10-11: Time Period (ms) Byte 12-13: Delayed Start Time (ms) Byte 14: Repeat Count (0-254, 255: Forever) For a Read: Input: Byte 0: Channel Output: Byte 0-17: Matches Write format

For example, to stop and clear the LED, the command is [0x02, 0x02, 0x01].

• 0x02 is the Opcode
• 0x03 is the Stop Setting Register
• 0x00 is the Byte 0 of the Value, it means Stop when the value is 0

For example, to Flash the LED, the command is [0x02, 0x03, 0x00, 0x02, 0x1f, 0x00, 0x00, 0x00, 0x32, 0x00, 0x00, 0x00, 0xf4, 0x01, 0x00, 0x00, 0x0a].

• 0x02 is the Opcode
• 0x03 is the Mode Setting Register
• 0x00 is the Byte 0 of the Value for the Green channel
• 0x02 is the Byte 1 of the Value for the Mode where 0x02 is the Flash mode
• 0x1f is the Byte 2 of the Value is the intensity when the led is on
• 0x00 is the Byte 3 of the Value is the intensity when the led is off (we want it all the way off)
• 0x00 0x00 is the Byte 4-5 of the Value is the time to turn on in ms (0ms)
• 0x32 0x00 is the Byte 6-7 of the Value is the time to stay on in ms (12800ms)
• 0x00 0x00 is the Byte 8-9 of the Value is the time to turn off in ms (0ms)
• 0xf4 0x01 is the Byte 10-11 of the Value is the time period (62465 ms)
• 0x00 0x00 is the Byte 12-13 of the Value is how long to delay the pattern (0 ms)
• 0x0a is the Byte 14 of the Value is how many times the pattern should be repeated (10 times)

0x03 - Accelerometer Module

The Module Opcode is 0x03.

The Accelerometer Module allows users to get data from the 3-axis accelerometer. It is also used to set the accelerometer to sense taps, steps walked, flatness, or orientation.

An accelerometer is an electromechanical device that will measure acceleration forces. These forces may be static, like the constant force of gravity pulling at your feet, or they could be dynamic - caused by moving or vibrating the accelerometer.

Acceleration is measured in units of gravities (g) or units of m/s2. One g unit \= 9.81 m/s2.

The accelerometer settings such as the range, the power mode, or the sampling rate are available via the various Setting registers.

Because the MMS and the MMRL have different accelerometers, the Module Info Setting determines which accelerometer is available:

• Revision Value 0 \= BOSCH BMI270
• Revision Value 2 \= BOSCH BMI160

The Accelerometer Module exposes almost all of the registers of the BMI160 and the BMI270 via the Setting registers. Refer to their datasheets for the definition of the exposed registers such as PMU_STATUS or ACC_CONF:

• BOSCH BMI160 DATASHEET
• BOSCH BMI270 DATASHEET

For the BMI160:

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Module information. Read: Byte 1: Module Implementation ID: 0x01 (uint8_t) Byte 2: Module Revision: 0x02 (uint8_t)
Accel Power Mode	0x01	W	1	1	Switch Accelerometer Power modes. Write: To the corresponding BMI160 Register. Byte 1: PMU_STATUS Value 0x00 \= Suspend Value 0x01 \= Normal Value 0x02 \= Low Power
Accel Data Interrupt Enable	0x02	RW	2	1	Turn the data ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: enable accel data ready int Byte 2: Disable Bit Mask Bit 0: disable accel data ready int Read: Byte 1 - Enable Bit Mask
Accel Data Config	0x03	RW	2	2	Sets ODR and Bandwith. Read/Write: To the corresponding BMI160 Registers. Byte 1: ACC_CONF Bit 0 - 3: uint8_t odr Bit 4 - 6: uint8_t bwp Bit 7: uint8_t us Byte 2: ACC_RANGE Bit 0 - 3: uint8_t range Bit 4 - 7: unused
Accel Data Interrupt	0x04	RN		6	Accelerometer data. Read/Notify: Byte 1 - 2: X: int16_t Byte 3 - 4: Y: int16_t Byte 5 - 6: Z: int16_t
Accel Data Interrupt Config	0x05	RW	2	2	Controls the input filtering to several of the motion state machines. Read/Write: To the corresponding BMI160 Register. Byte 1 - 2: INT_DATA See the datasheet
Low-G/High-G Interrupt Enable	0x06	RW	2	1	Turn the low/high-G data ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: High-G X Bit 1: High-G Y Bit 2: High-G Z Bit 3: Low-G Byte 2: Disable Bit Mask Bit 0: High-G X Bit 1: High-G Y Bit 2: High-G Z Bit 3: Low-G Read: Byte 1: Enable Bit Mask
Low-G/High-G Config	0x07	RW	5	5	Configures the low/highG mode. Read/Write: To the corresponding BMI160 Register. Byte 1 - 5: INT_LOWHIGH See the datasheet
Low-G/High-G Interrupt	0x08	N		1	Accelerometer low/high-G data. Notify: To the corresponding BMI160 Register: Byte 1: INT_STATUS - Notification Bitmask Bit 0: High-G Int Bit 1: Low-G Int Bit 2: High First X Bit 3: High First Y Bit 4: High First Z Bit 5: High Sign
Motion Interrupt Enable	0x09	RW	2	1	Turn the motion data ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: Any Motion X Bit 1: Any Motion Y Bit 2: Any Motion Z Bit 3: No Motion X Bit 4: No Motion Y Bit 5: No Motion Z Byte 2: Disable Bit Mask Bit 0: Any Motion X Bit 1: Any Motion Y Bit 2: Any Motion Z Bit 3: No Motion X Bit 4: No Motion Y Bit 5: No Motion Z Read: Byte 1: Enable Bit Mask
Motion Config	0x0A	RW	4	4	Configures the motion mode. Read/Write: To the corresponding BMI160 Register: Byte 1 - 4: INT_MOTION See the datasheet
Motion Interrupt	0x0B	N		1	Accelerometer motion data. Notify: To the corresponding BMI160 Register: Byte 1: INT_STATUS - Notification Bitmask: Bit 0: Significant Motion Int Bit 1: Any Motion Int Bit 2: No Motion Int Bit 3: Any Motion First X Bit 4: Any Motion First Y Bit 5: Any Motion First Z Bit 6: Any Motion Sign
Tap Interrupt Enable	0x0C	RW	2	1	Turn the tap ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: Double Tap Bit 1: Single Tap Byte 2: Disable Bit Mask Bit 0: Double Tap Bit 1: Single Tap Read: Enabled Bit Mask
Tap Config	0x0D	RW	2		Configures the tap mode. Read/Write: To the corresponding BMI160 Register: Byte 1 - 2: INT_TAP See the datasheet
Tap Interrupt	0x0E	N		1	Accelerometer tap data. Notify: To the corresponding BMI160 Register Byte 1: INT_STATUS - Notification Bitmask: Bit 0: Double Tap Int Bit 1: Single Tap Int Bit 2: Tap First X Bit 3: Tap First Y Bit 4: Tap First Z Bit 5: Tap Sign
Orient Interrupt Enable	0x0F	RW	2	1	Turn the orientation ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: Orientation Byte 2: Disable Bit Mask Bit 0: Orientation Read: Byte 1: Enable Bit Mask
Orient Config	0x10	RW	2	2	Configures the orientation mode. Read/Write: To the corresponding BMI160 Register: Byte 1 - 2: INT_ORIENT See the datasheet
Orient Interrupt	0x11	N		1	Accelerometer orientation data. Notify: To the corresponding BMI160 Register Byte 1: INT_STATUS - Notification Bitmask: Bit 0: Orientation Int Bit 1-2: Orientation
Flat Interrupt Enable	0x12	RW	2	1	Turn the flatness ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: Flat Byte 2: Disable Bit Mask Bit 0: Flat Read: Byte 1: Enable Bit Mask
Flat Config	0x13	RW	2	2	Configures the flatness mode. Read/Write: To the corresponding BMI160 Register: Byte 1 - 2: INT_FLAT See the datasheet
Flat Interrupt	0x14	N		1	Accelerometer flatness data. Notify: To the corresponding BMI160 Register Byte 1: INT_STATUS - Notification Bitmask: Bit 0: Flat Int Bit 1: Z-Axis Orientation (0: Face Up, 1: Face Down) Bit 2: Flat
Data Offset	0x15	RW	7	7	Offset compensations values for acc and gyro. Read/Write: To the corresponding BMI160 Register: OFFSET Byte 1: acc_off_x Byte 2: acc_off_y Byte 3: acc_off_z Byte 4: gyr_off_x Byte 5: gyr_off_y Byte 6: gyr_off_z Byte 7: enable and extra bits, see datasheet
Power Mode Status	0x16	R		1	Present power state of accel/gyro functions. Read: To the corresponding BMI160 Register: PMU_STATUS Byte 1: PMU_STATUS Bit 0 - 1: mag pmu status Bit 2 - 3: gyro pmu status Bit 4 - 5: acc_pmu status Bit 6 - 7: unused
Step Detector Interrupt Enable	0x17	RW	2	1	Turn the step detector ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: Step Detector Int Byte 2: Disable Bit Mask Bit 0: Step Detector Int Read: Byte 1: Enable Bit Mask
Step Detector Config	0x18	RW	2	2	Configures the step detector mode. Read/Write: To the corresponding BMI160 Register: Byte 1 - 2: STEP_CONF See the datasheet
Step Detector Status	0x19	N		1	Step data interrupt. Notify: To the corresponding BMI160 Register Byte 1: INT_STATUS - Notification Bitmask: Bit 0: Step Detector Int
Step Counter Data	0x1a	R	2	2	Step count data. Read: Byte 1 - 2: uint16_t Step Count
Step Counter Reset	0x1b	W	1	1	Reset step counter. Write: Any write causes a reset
Data Packed Accel Data	0x1c	N	18	18	Accumulated Vector Output of Register 0x04 Notify: Data Value int16_t (X, Y, Z)[3]: Byte 1 - 2: X: int16_t Byte 3 - 4: Y: int16_t Byte 5 - 6: Z: int16_t Byte 7 - 8: X: int16_t Byte 9 - 10: Y: int16_t Byte 11 -12: Z: int16_t Byte 13 - 14: X: int16_t Byte 15 - 16: Y: int16_t Byte 17 - 18: Z: int16_t

For the BMI270:

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Module information. Read: Byte 1: Module Implementation ID: 0x04 (uint8_t) Byte 2: Module Revision: 0x00 (uint8_t)
Accel Power Mode	0x01	W	1	1	Switch Accelerometer Power modes. Write: To the corresponding BMI270 Register. Byte 1: PMU_STATUS Value 0x00 \= Suspend Value 0x01 \= Normal Value 0x02 \= Low Power
Accel Data Interrupt Enable	0x02	RW	2	1	Turn the data ready interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Bit 0: enable accel data ready int Byte 2: Disable Bit Mask Bit 0: disable accel data ready int Read: Byte 1 - Enable Bit Mask
Accel Data Config	0x03	RW	2	2	Sets ODR and Bandwith. Read/Write: To the corresponding BMI270 Registers. Byte 1: ACC_CONF Bit 0 - 3: uint8_t odr Bit 4 - 6: uint8_t bwp Bit 7: uint8_t filter_perf Byte 2: ACC_RANGE Bit 0 - 1: uint8_t range Bit 2 - 7: unused
Accel Data Interrupt	0x04	RN		6	Accelerometer data. Read/Notify: Byte 1 - 2: X: int16_t Byte 3 - 4: Y: int16_t Byte 5 - 6: Z: int16_t
Data Packed Accel Data	0x05	N	18	18	Accumulated Vector Output of Register 0x04 Notify: Data Value int16_t (X, Y, Z)[3]: Byte 1 - 2: X: int16_t Byte 3 - 4: Y: int16_t Byte 5 - 6: Z: int16_t Byte 7 - 8: X: int16_t Byte 9 - 10: Y: int16_t Byte 11 -12: Z: int16_t Byte 13 - 14: X: int16_t Byte 15 - 16: Y: int16_t Byte 17 - 18: Z: int16_t
Feature Enable	0x06	RW	2	1	Enabes the different motion features of the BMI270 Write: Byte 1: Enable Bit Mask Byte 2: Disable Bit Mask Bit 0: Sig Motion Bit 1: Step Counter Bit 2: Activity Out Bit 3: Wrist Wakeup Bit 4: Wrist Gesture Bit 5: No Motion Bit 6: Any Motion Bit 7: Step Detector Read: Byte 1: Enable Bit Mask
Feature Int Enable	0x07	RW	2	1	Turn the different feature interrupt ON/OFF. Write: Byte 1: Enable Bit Mask Byte 2: Disable Bit Mask Bit 0: Sig Motion Bit 1: Step Counter Bit 2: Activity Out Bit 3: Wrist Wakeup Bit 4: Wrist Gesture Bit 5: No Motion Bit 6: Any Motion Bit 7: Step Detector Read: Byte 1: Enable Bit Mask
Feature Config	0x08	RW	17	1	Feature Config Bytes Write: Byte 1: Config Bank Index Bit 0: Axis Remap Bit 1: Any Motion Bit 2: No Motion Bit 3: Sig Motion Bit 4: Step Counter 0 Bit 5: Step Counter 1 Bit 6: Step Counter 2 Bit 7: Step Counter 3 Bit 8: Wrist Gesture Bit 9: Wrist Wakeup Byte 2-16: Config Data (See datasheet for BMI270 registers:) Byte 2 - 3: GEN_SET_1 Byte 4 - 5: ANYMO_1 Byte 6 - 7: NOMO_1 Byte 8: SIGMO_1 Byte 9 - 10: STEP_COUNTER_1 Byte 11 - 12: STEP_COUNTER_2 Byte 13 - 14: STEP_COUNTER_3 Byte 15 - 16: STEP_COUNTER_4 Byte 17: WR_GEST_1 Byte 17: WR_WAKEUP_1 Read: Byte 1: Config Bank Index
Motion Interrupt	0x09	N	1	1	Motion data. Notify: Byte 1 Bit 0: Sig Motion Bit 1: No Motion Bit 2: Any Motion
Wrist Interrupt	0x0a	N	1	1	Wrist data. Notify: Byte 1 Bit 0: Wrist Wear Wakeup Bit 1: Wrist Gesture Bit 2 - 4: Gesture Code 0 \= Unknown 1 \= Push Arm Down 2 \= Pivot Up 3 \= Wrist Shake/Jiggle 4 \= Arm Flick In 5 \= Arm Flick Out
Step Count Interrupt	0x0b	RN	2	2	Step Count data. Notify/Read: Bytes 1 - 2: Step Count uint16_t
Activity Interrupt	0x0c	N	1	1	Activity data. Notify: Byte 1 Bit 0: Activity Bit 1-2: Activity Code 0 \= Still 1 \= Walking 2 \= Running 3 \= Unknown
Temp Enable	0x0d	W	1		Temp Sensor Enable. Write: Byte 1: Input Values: 0 \= Off 1 \= On
Temperature	0x0e	R	2	2	Sensor Temperature. temp \= (1C/512)*value+23C Read: Bytes 0 - 1: int16_t in units of (1./512 degC), offset by 23C
Offset	0x0f	RW	4	4	Offset compensation for accel. Corresponding to BMI270 Registers below (see datasheet). Read/Write: Byte 1: NV_CONF Byte 2: OFFSET0 Bit 0 - 7: off acc x Byte 3: OFFSET1 Bit 0 - 7: off acc y Byte 4: OFFSET2 Bit 0 - 7: off acc z
Downsampling	0x10	RW	1	1	Configure gyro/acell downsampling rates for FIFO. Corresponding to BMI270 Registers. Read/Write: Byte 1: FIFO_DOWNS (see the datasheet) Bit 0 - 2: gyro fifo down Bit 3: gyro fifo filt data Bit 4 - 6: acc fifo down Bit 7: acc fifo filt data

Linear acceleration is represented with the MblMwCartesianFloat struct and the values are in units of Gs. The x, y, and z fields contain the acceleration in that direction.

Sample data:

0x04 - Temperature Module

The Module Opcode is 0x04.

The Temperature Module allows users to read temperature data from up to three different sources on the MetaWear: an on-die sensor (inside the chip), an on-board thermistor, and an external thermistor that can be connected to the GPIO pins.

Temperature is returned as a signed 16-bit integer (int16_t) in units of 0.125°C.

The Temperature register (0x01) requires an index byte in the Value field to select which sensor to read from:

• Index 0x00 \= On-die temperature sensor (nRF)
• Index 0x01 \= On-board thermistor
• Index 0x02 \= External thermistor (connected via GPIO)
• Index 0x03 \= BMP280 temperature sensor (Barometer on-chip)

The Thermistor Mode register (0x05) is used to configure the external thermistor GPIO pin, data pin, and whether the sensor is active high or active low.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Temperature	0x01	RN		2	Read: Byte 0: Sensor Index (uint8_t) Response: Byte 0: Sensor Index Byte 1-2: Temperature int16_t in units of 0.125°C
Mode	0x02	RW	8	8	Byte 0-7: Temperature sensor mode configuration
Delta Temp	0x03	N		4	Byte 0-3: Temperature delta notification data
Threshold Detect	0x04	N		4	Byte 0-3: Temperature threshold detection notification data
Thermistor Mode	0x05	RW	3	3	Byte 0: GPIO Analog Pin (uint8_t) Byte 1: GPIO Data Pin (uint8_t) Byte 2: Active High/Low (uint8_t, 0 \= active low, 1 \= active high)

For example, to read the on-die temperature, the command is [0x04, 0x81, 0x00]:

• 0x04 is the Opcode for the Temperature module
• 0x81 is the Address 0x01 OR'd with 0x80 for a read
• 0x00 is the sensor index for the on-die sensor

The response might be [0x04, 0x81, 0x00, 0xC8, 0x00]:

• 0x04 is the Opcode
• 0x81 is the Address with read bit set
• 0x00 is the sensor index
• 0xC8 0x00 is the temperature value (200 in decimal \= 200 × 0.125°C \= 25.0°C)

0x05 - GPIO Module

The Module Opcode is 0x05.

The GPIO Module allows users to interact with the General Purpose Input/Output pins on the MetaWear. Pins can be configured as digital outputs (set high or low), digital inputs (with pull-up, pull-down, or no-pull resistors), or analog inputs (read as an absolute voltage or as a supply ratio).

Pin change notifications can be configured to send a notification when a digital input pin changes state. The pin change type determines which transitions to monitor (rising edge, falling edge, or both).

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Set Digital Output	0x01	W	1		Byte 0: Pin Number (uint8_t) - Sets the pin HIGH
Clear Digital Output	0x02	W	1		Byte 0: Pin Number (uint8_t) - Sets the pin LOW
Digital In Pull Up	0x03	W	1		Byte 0: Pin Number (uint8_t) - Configures pin as digital input with pull-up resistor
Digital In Pull Down	0x04	W	1		Byte 0: Pin Number (uint8_t) - Configures pin as digital input with pull-down resistor
Digital In No Pull	0x05	W	1		Byte 0: Pin Number (uint8_t) - Configures pin as digital input with no pull resistor
Read Analog Input Absolute Reference	0x06	R	1	3	Read: Byte 0: Pin Number (uint8_t) Response: Byte 0: Pin Number Byte 1-2: Analog value uint16_t in mV
Read Analog Input Supply Ratio	0x07	R	1	3	Read: Byte 0: Pin Number (uint8_t) Response: Byte 0: Pin Number Byte 1-2: Analog value uint16_t as ratio of supply voltage (0-4095)
Read Digital Input	0x08	R	1	2	Read: Byte 0: Pin Number (uint8_t) Response: Byte 0: Pin Number Byte 1: Digital Value (0 or 1)
Set Pin Change	0x09	RW	2	2	Byte 0: Pin Number (uint8_t) Byte 1: Change Type (uint8_t, 1 \= Rising, 2 \= Falling, 3 \= Any)
Pin Change Notification	0x0A	N		2	Byte 0: Pin Number (uint8_t) Byte 1: Pin State (uint8_t)
Pin Change Notification Enable	0x0B	W	2		Byte 0: Pin Number (uint8_t) Byte 1: Enable (0 \= disable, 1 \= enable)

0x08 - Haptic Module

The Module Opcode is 0x08.

The Haptic Module drives the buzzer motor on MetaWear boards that have one (MMS+ or MMRL+). It uses a simple pulse command to vibrate the buzzer for a specified duration at a specified duty cycle.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Pulse	0x01	W	4		Byte 0: Duty Cycle (uint8_t, 0-248) Byte 1-2: Pulse Width in ms (uint16_t) Byte 3: Buzzer (uint8_t, 0 \= Motor, 1 \= Buzzer)

For example, to pulse the buzzer for 500ms at full duty cycle, the command is [0x08, 0x01, 0xF8, 0xF4, 0x01, 0x01]:

• 0x08 is the Opcode for the Haptic module
• 0x01 is the Address for the Pulse register
• 0xF8 is the duty cycle (248 \= max)
• 0xF4 0x01 is 500 in uint16_t little-endian (500ms)
• 0x01 selects the buzzer mode

0x09 - Data Processor Module

The Module Opcode is 0x09.

The Data Processor Module provides on-board data processing filters and transformations. Filters can be chained together to create complex data pipelines that run entirely on the MetaWear without requiring a Bluetooth connection.

A filter is created by writing a filter configuration to the Add register. The filter receives input from a data source (a sensor register or another filter) and outputs processed data. Filters are identified by a filter ID returned when the filter is created.

The filter notification system allows the host to receive processed data. The Notify Enable register turns on notifications for a specific filter, and processed data is received via the Notify register.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Enable	0x01	RW	1	1	Byte 0: Enable (0 \= disable, 1 \= enable global data processor)
Add / Create Filter	0x02	RW	18	18	Write: Byte 0: Source Module ID Byte 1: Source Register ID Byte 2: Source Data Offset Byte 3: Source Data Length Byte 4: Filter Type ID Byte 5-17: Filter-specific configuration Read (Response): Byte 0: Filter ID (uint8_t)
Filter Notification	0x03	N		18	Byte 0: Filter ID (uint8_t) Byte 1-17: Processed data (format depends on filter type)
Filter State	0x04	RW	18	18	Write: Byte 0: Filter ID Byte 1-17: State data Read: Byte 0: Filter ID (input) Byte 1-17: Current state (output)
Filter Param Modify	0x05	W	18		Byte 0: Filter ID (uint8_t) Byte 1-17: Updated filter parameters
Filter Remove	0x06	W	1		Byte 0: Filter ID (uint8_t) - Removes the specified filter
Notify Enable	0x07	W	1		Byte 0: Filter ID (uint8_t) Byte 1: Enable (0 \= disable, 1 \= enable notifications)
Remove All	0x08	W			No value required - Removes all filters

The available filter types are:

Filter Type ID	Name	Description
0x01	Passthrough	Passes data through, optionally with a count limit
0x02	Counter / Accumulator	Counts events or accumulates values
0x03	Averaging	Low memory recursive average / low pass filter
0x04	Comparator	Compares input against a reference value
0x05	RMS	Root mean square of multi-component data
0x06	Time Delay	Delays or downsamples data by time
0x07	Math	Performs arithmetic operations on data
0x08	Sample Delay	Delays data by a fixed number of samples
0x09	Data Packer	Packs multiple data samples into one notification
0x0A	Account	Adds timestamps to data
0x0B	Threshold	Detects when data crosses a threshold
0x0C	Delta	Detects when data changes by a specified amount
0x0D	Fuser	Combines data from multiple sources
0x0E	Buffer	Stores the latest data sample for later retrieval

0x0A - Event Module

The Module Opcode is 0x0A.

The Event Module allows users to program automatic responses to data events on the MetaWear. When an event source fires (such as a sensor data ready interrupt, a button press, or a timer tick), the MetaWear can automatically execute one or more commands without host intervention.

Events are created by recording a command sequence: the host begins recording, sends the commands that should be executed when the event fires, and then ends recording. The MetaWear stores these commands and replays them each time the event triggers.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Entry	0x02	RW	18	18	Write: Byte 0: Source Module ID Byte 1: Source Register ID Byte 2: Source Data Offset Byte 3-17: Event entry configuration Read (Response): Byte 0: Event ID (uint8_t)
Cmd Parameters	0x03	W	18		Byte 0: Event ID (uint8_t) Byte 1-17: Command bytes to execute when event fires
Remove	0x04	W	1		Byte 0: Event ID (uint8_t) - Removes the specified event
Remove All	0x05	W			No value required - Removes all events

0x0B - Logging Module

The Module Opcode is 0x0B.

The Logging Module allows users to record sensor data directly to the on-board flash memory of the MetaWear. This is useful when the host device (phone or computer) is not connected or when continuous streaming is not practical.

Logging works by adding triggers that specify which data sources to log. Once logging is enabled, data from those sources is written to flash with timestamps. The logged data can later be downloaded via the Readout register.

The MetaWear has limited flash storage. When the log is full, behavior depends on the Circular Buffer Mode: if enabled, the oldest entries are overwritten; if disabled, logging stops.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		5	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t) Byte 2: Max Log Triggers (uint8_t) Byte 3-4: Max Log Time (uint16_t)
Enable	0x01	RW	1	1	Byte 0: Enable (0 \= disable, 1 \= enable logging)
Add Trigger	0x02	RW	4	4	Write: Byte 0: Source Module ID Byte 1: Source Register ID Byte 2: Source Data Offset Byte 3: Source Data Length Read (Response): Byte 0: Trigger ID (uint8_t)
Remove Trigger	0x03	W	1		Byte 0: Trigger ID (uint8_t)
Time	0x04	R		4	Byte 0-3: Current logging timestamp (uint32_t)
Length	0x05	R		2	Byte 0-1: Number of log entries (uint16_t)
Readout	0x06	RW	4	4	Write: Byte 0-3: Number of entries to read out (uint32_t) Read: Byte 0-3: Readout status
Readout Notify	0x07	N		18	Byte 0: Trigger ID (uint8_t) Byte 1-4: Timestamp (uint32_t) Byte 5-17: Logged data
Readout Progress	0x08	N		2	Byte 0-1: Entries remaining to be read (uint16_t)
Drop Entries	0x09	W	2		Byte 0-1: Number of entries to drop (uint16_t)
Remove All Triggers	0x0A	W			No value required - Removes all log triggers
Circular Buffer Mode	0x0B	RW	1	1	Byte 0: Enable (0 \= stop when full, 1 \= overwrite oldest)
Recycled Page Count	0x0C	R		2	Byte 0-1: Number of recycled pages (uint16_t)
Page Completed	0x0D	N			Notification sent when a readout page is completed
Page Confirm	0x0E	W			Confirms receipt of a readout page, triggers next page
Page Flush	0x10	W			Flushes the current page to flash

0x0C - Timer Module

The Module Opcode is 0x0C.

The Timer Module provides a built-in timer that fires at a configurable interval. Timers are used in conjunction with the Event Module to periodically execute commands such as reading a sensor, toggling an LED, or streaming data at a fixed rate.

Multiple timers can be created and run simultaneously. Each timer is assigned a Timer ID when created.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Enable	0x01	RW	1	1	Byte 0: Timer ID (uint8_t) - Enables the specified timer
Timer Entry	0x02	RW	7	7	Write: Byte 0-3: Period in ms (uint32_t) Byte 4-5: Repeat Count (uint16_t, 0xFFFF \= indefinite) Byte 6: Delay Start (uint8_t, 0 \= no delay) Read (Response): Byte 0: Timer ID (uint8_t)
Start	0x03	W	1		Byte 0: Timer ID (uint8_t) - Starts the timer
Stop	0x04	W	1		Byte 0: Timer ID (uint8_t) - Stops the timer
Remove	0x05	W	1		Byte 0: Timer ID (uint8_t) - Removes the timer
Notify	0x06	N		1	Byte 0: Timer ID (uint8_t) - Notification sent when timer fires
Notify Enable	0x07	W	2		Byte 0: Timer ID (uint8_t) Byte 1: Enable (0 \= disable, 1 \= enable notifications)

0x0D - Serial Passthrough Module

The Module Opcode is 0x0D.

The Serial Passthrough Module provides direct access to the I2C and SPI buses on the MetaWear. This allows users to communicate with external sensors and peripherals connected to the MetaWear board.

For I2C, the host specifies the device address, register address, and the data to read or write. For SPI, the host specifies the chip select pin, clock rate, and data.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
I2C Read/Write	0x01	RW	18	18	Write: Byte 0: Device Address (uint8_t, 7-bit I2C address) Byte 1: Register Address (uint8_t) Byte 2: ID (uint8_t, identifier for tracking) Byte 3: Data Length (uint8_t) Byte 4+: Data to write Read: Byte 0: ID Byte 1: Device Address Byte 2: Register Address Byte 3+: Data read from device
SPI Read/Write	0x02	RW	18	18	Write: Byte 0: SPI Mode / LSB First Byte 1: CS Pin Byte 2: CLK Pin Byte 3: MOSI Pin Byte 4: MISO Pin Byte 5: Data Length Byte 6: ID Byte 7+: Data to send Read: Byte 0: ID Byte 1+: Data received from device

0x0F - Macro Module

The Module Opcode is 0x0F.

The Macro Module allows users to store a sequence of commands in the MetaWear's non-volatile memory. These stored commands are executed on boot or on demand, allowing the MetaWear to operate autonomously without a host connection.

Macros are recorded by sending a Begin command, followed by the individual commands to store, and then an End command. The MetaWear assigns each macro a Macro ID. Macros persist across resets and power cycles.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Enable	0x01	RW	1	1	Byte 0: Macro ID - Enables execution of a macro on boot
Begin Macro	0x02	RW	1	3	Write: Byte 0: Execute on boot (0 \= no, 1 \= yes) Read (Response): Byte 0: Macro ID (uint8_t)
Add Command	0x03	W	18		Byte 0-17: Command bytes to add to the current macro (same format as any command sent to the Command Characteristic)
End Macro	0x04	W			No value required - Ends macro recording
Execute	0x05	W	1		Byte 0: Macro ID (uint8_t) - Executes the specified macro
Finish Notification Enable	0x06	W	2		Byte 0: Macro ID (uint8_t) Byte 1: Enable (0 \= disable, 1 \= enable)
Macro Finished	0x07	N		1	Byte 0: Macro ID (uint8_t) - Notification sent when macro execution completes
Erase All	0x08	W			No value required - Erases all stored macros
Add Partial Command	0x09	W	18		Byte 0-17: Partial command data for commands that exceed 18 bytes. Send partial first, then full command with Add Command.

0x11 - Settings Module

The Module Opcode is 0x11.

The Settings Module is the most important module because it is used to determine which MetaWear device is connected. It is also used to control how the MetaWear advertises and how strong the Bluetooth connection is.

The Module Info determines the module revision:

• Revision 0x01 \= MMRL (MetaMotionRL)
• Revision 0x05 \= MMS (MetaMotionS)

The MMS has the additional capability of being able to indicate when it is charging.

The Device Name is “MetaWear” by default but can be changed.

Bluetooth devices typically advertise every 100ms to 1sec. The advertising only takes 1 or 2 milliseconds so that most of the time the device is not advertising. This conserves power and is one of the strategies behind Bluetooth LE's low power. The MetaWear Advertising Interval is configurable.

Bluetooth power is expressed in Decibel-milliwatt (dBm), the unit used to measure radio frequency (RF) power level. For a Bluetooth device, 0dBm is the standard power level and +4dBm is just over a doubling of power. -3dBm will be half power, -6dBm will be a 1/4 power and -9dBm 1/8 power. Each change in ±3dBM is a doubling/halving of power. The MetaWear TX Power is configurable.

Bonding is not currently supported.

Custom advertising packets are possible on MetaSensors using the Partial Scan Response Packet and Scan Response Packet which you can turn on and off using Start Advertisement.

The Connection Parameters for a BLE connection are a set of parameters that determine when and how the central and peripheral in a link transmit data. The parameters are exchanged when the central and peripheral initially connect. It is always the central that actually sets the connection parameters used, but the peripheral can send a Connection Parameter Update Request, that the central can then accept or reject.

The three different parameters are:

1. Connection Interval: Determines how often the central will ask for data from the peripheral. When the peripheral requests an update, it supplies a maximum and a minimum wanted interval. The connection interval must be between 7.5 ms and 4 s.
2. Slave Latency: By setting a non-zero slave latency, the peripheral can choose not to answer when the central asks for data up to the slave latency number of times. However, if the peripheral has data to send, it can choose to send data at any time. This enables a peripheral to stay sleeping for a longer time if it doesn't have data to send but still send data fast if needed.
3. Connection Supervision Timeout: This timeout determines the timeout from the last data exchange until a link is considered lost. The central will not try to reconnect before the timeout has passed, so if you have a device that goes in and out of range often and you need to notice when that happens, it might make sense to have a short timeout.

The MMS is also able to provide users with the ability to read the charge of the battery and determine if the battery is plugged in or not using the Battery State, Charger Status and Power Status. The power status determines if a USB cable is plugged into the MMS. The charger status determines if the battery finished charging or not.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: see above (uint8_t)
Device Name	0x01	RW	8	8	Byte 0-7: Device name as ASCII characters (up to 8 bytes, null terminated)
Advertising Interval	0x02	RW	3	3	Byte 0-1: Interval in units of 0.625ms (uint16_t) Byte 2: Timeout in seconds (uint8_t, 0 \= no timeout)
TX Power	0x03	RW	1	1	Byte 0: TX Power Level in dBm (int8_t). Valid values: -40, -20, -16, -12, -8, -4, 0, 4
Start Advertisement	0x05	W			No value required - Starts advertising with current settings
Scan Response Packet	0x07	RW	18	18	Byte 0-17: Custom scan response data (up to 18 bytes)
Partial Scan Response	0x08	W	13		Byte 0-12: Partial scan response data (for packets exceeding 18 bytes)
Connection Parameters	0x09	RW	8	8	Byte 0-1: Min Connection Interval in units of 1.25ms (uint16_t) Byte 2-3: Max Connection Interval (uint16_t) Byte 4-5: Slave Latency (uint16_t) Byte 6-7: Supervision Timeout in units of 10ms (uint16_t)
Disconnect Event	0x0A	N		1	Byte 0: Disconnect reason code (uint8_t) - Notification sent on BLE disconnect
MAC Address	0x0B	R		6	Byte 0-5: Bluetooth MAC Address (6 bytes, little-endian)
Battery State	0x0C	RN		3	Byte 0: Battery charge percentage (uint8_t, 0-100) Byte 1-2: Battery voltage in mV (uint16_t)
Power Status	0x11	RN		1	Byte 0: Power Status (uint8_t, 1 \= USB plugged in, 0 \= not plugged in)
Charge Status	0x12	RN		1	Byte 0: Charge Status (uint8_t, 1 \= charging complete, 0 \= charging)
Whitelist Filter Mode	0x13	RW	1	1	Byte 0: Filter mode (uint8_t)
Whitelist Addresses	0x14	RW	7	7	Byte 0: Address entry index (uint8_t) Byte 1: Address type (uint8_t) Byte 2-7: BLE Address (6 bytes)
3V Power	0x1C	RW	1	1	Byte 0: Enable 3.3V regulator (uint8_t, 0 \= off, 1 \= on)
Force 1M PHY	0x1D	RW	1	1	Byte 0: Force 1M PHY (uint8_t, 0 \= allow 2M PHY, 1 \= force 1M PHY)

0x12 - Barometer Module

The Module Opcode is 0x12.

The Barometer Module provides access to the BOSCH BMP280 pressure sensor on the MetaWear. It can read barometric pressure and estimate altitude based on the pressure reading.

Pressure is returned as an unsigned 32-bit integer in units of Pa (Pascals) with a scaling factor of 256 (divide by 256 to get the actual pressure in Pa). Altitude is returned as a signed 32-bit integer in units of cm.

The barometer can be configured to run in single-shot or cyclic mode. In cyclic mode, the sensor continuously measures at the configured rate. The configuration register maps to the BMP280 registers for oversampling, filtering, and standby time.

Refer to the BOSCH BMP280 Datasheet for detailed register configuration.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Pressure	0x01	RN		4	Byte 0-3: Pressure uint32_t in units of Pa/256 (divide by 256.0 to get Pa)
Altitude	0x02	RN		4	Byte 0-3: Altitude int32_t in units of cm
Config	0x03	RW	7	7	Byte 0: Oversampling for pressure (uint8_t, see BMP280 datasheet) Byte 1: Oversampling for temperature (uint8_t) Byte 2: IIR Filter Coefficient (uint8_t) Byte 3-4: Standby Time in ms (uint16_t) Byte 5: Output Data Rate / Mode Byte 6: Reserved
Cyclic	0x04	RW	2	1	Write: Byte 0: Enable Bit Mask (Bit 0: Pressure, Bit 1: Altitude) Byte 1: Disable Bit Mask Read: Byte 0: Enable Bit Mask

0x13 - Gyroscope Module

The Module Opcode is 0x13.

The Gyroscope Module provides access to the 3-axis gyroscope on the MetaWear. The gyroscope measures angular velocity (rotational speed) in degrees per second (°/s).

Because the MMS and the MMRL have different IMUs, the Module Info determines which gyroscope is available:

• Implementation ID 0x00 \= BOSCH BMI160
• Implementation ID 0x01 \= BOSCH BMI270

Angular velocity is returned as three signed 16-bit integers (int16_t) for X, Y, and Z axes. The raw values must be converted using the configured range. The gyroscope supports configurable output data rate (ODR) and full-scale range.

Refer to the datasheets for detailed register configuration:

• BOSCH BMI160 DATASHEET
• BOSCH BMI270 DATASHEET

For the BMI160:

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0x00 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Gyro Power Mode	0x01	W	1		Switch Gyroscope Power modes. Write: Byte 0: Value 0x00 \= Suspend Value 0x01 \= Normal
Gyro Data Interrupt Enable	0x02	RW	2	1	Turn the data ready interrupt ON/OFF. Write: Byte 0: Enable Bit Mask (Bit 0: enable gyro data ready int) Byte 1: Disable Bit Mask Read: Byte 0: Enable Bit Mask
Gyro Data Config	0x03	RW	2	2	Sets ODR and Range. Read/Write: Byte 0: GYR_CONF (BMI160) Bit 0-3: uint8_t odr Bit 4-5: uint8_t bwp Byte 1: GYR_RANGE Bit 0-2: uint8_t range (0 \= 2000°/s, 1 \= 1000°/s, 2 \= 500°/s, 3 \= 250°/s, 4 \= 125°/s)
Gyro Data Interrupt	0x05	RN		6	Gyroscope data. Read/Notify: Byte 0-1: X: int16_t Byte 2-3: Y: int16_t Byte 4-5: Z: int16_t
Packed Gyro Data	0x07	N		18	Accumulated Vector Output of Register 0x05. Notify: int16_t (X, Y, Z)[3]: Byte 0-1: X Byte 2-3: Y Byte 4-5: Z Byte 6-7: X Byte 8-9: Y Byte 10-11: Z Byte 12-13: X Byte 14-15: Y Byte 16-17: Z

For the BMI270:

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0x01 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Gyro Power Mode	0x01	W	1		Switch Gyroscope Power modes. Write: Byte 0: Value 0x00 \= Suspend Value 0x01 \= Normal
Gyro Data Interrupt Enable	0x02	RW	2	1	Turn the data ready interrupt ON/OFF. Write: Byte 0: Enable Bit Mask (Bit 0: enable gyro data ready int) Byte 1: Disable Bit Mask Read: Byte 0: Enable Bit Mask
Gyro Data Config	0x03	RW	2	2	Sets ODR and Range. Read/Write: Byte 0: GYR_CONF (BMI270) Bit 0-3: uint8_t odr Bit 4-5: uint8_t bwp Bit 6: noise_perf Bit 7: filter_perf Byte 1: GYR_RANGE Bit 0-2: uint8_t range (0 \= 2000°/s, 1 \= 1000°/s, 2 \= 500°/s, 3 \= 250°/s, 4 \= 125°/s)
Gyro Data Interrupt	0x04	RN		6	Gyroscope data. Read/Notify: Byte 0-1: X: int16_t Byte 2-3: Y: int16_t Byte 4-5: Z: int16_t
Packed Gyro Data	0x05	N		18	Accumulated Vector Output of Register 0x04. Notify: int16_t (X, Y, Z)[3]: Byte 0-1: X Byte 2-3: Y Byte 4-5: Z Byte 6-7: X Byte 8-9: Y Byte 10-11: Z Byte 12-13: X Byte 14-15: Y Byte 16-17: Z
Offset	0x06	RW	6	6	Offset compensation for gyro. Read/Write: Byte 0-1: gyr_off_x (int16_t) Byte 2-3: gyr_off_y (int16_t) Byte 4-5: gyr_off_z (int16_t)

0x15 - Magnetometer Module

The Module Opcode is 0x15.

The Magnetometer Module provides access to the BOSCH BMM150 3-axis magnetometer on the MetaWear. The magnetometer measures the Earth's magnetic field and is commonly used for compass heading and orientation.

Magnetic field strength is returned as three signed 16-bit integers (int16_t) for X, Y, and Z axes in units of 0.0625 µT (micro-Tesla). The magnetometer supports configurable output data rate and repetition settings that affect accuracy and power consumption.

Refer to the BOSCH BMM150 DATASHEET for detailed register configuration.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Mag Power Mode	0x01	W	1		Switch Magnetometer Power modes. Write: Byte 0: Value 0x00 \= Suspend Value 0x01 \= Active / Normal
Mag Data Interrupt Enable	0x02	RW	2	1	Turn the data ready interrupt ON/OFF. Write: Byte 0: Enable Bit Mask (Bit 0: enable mag data ready int) Byte 1: Disable Bit Mask Read: Byte 0: Enable Bit Mask
Mag Data Rate	0x03	RW	1	1	Output data rate. Read/Write: Byte 0: ODR value (uint8_t, 0 \= 10Hz, 1 \= 2Hz, 2 \= 6Hz, 3 \= 8Hz, 4 \= 15Hz, 5 \= 20Hz, 6 \= 25Hz, 7 \= 30Hz)
Mag Data Repetitions	0x04	RW	2	2	Repetition settings for XY and Z axes. Read/Write: Byte 0: XY Repetitions (uint8_t, see BMM150 datasheet) Byte 1: Z Repetitions (uint8_t)
Mag Data	0x05	RN		6	Magnetometer data. Read/Notify: Byte 0-1: X: int16_t Byte 2-3: Y: int16_t Byte 4-5: Z: int16_t (in units of 0.0625 µT)
Packed Mag Data	0x09	N		18	Accumulated Vector Output of Register 0x05. Notify: int16_t (X, Y, Z)[3]: Byte 0-1: X Byte 2-3: Y Byte 4-5: Z Byte 6-7: X Byte 8-9: Y Byte 10-11: Z Byte 12-13: X Byte 14-15: Y Byte 16-17: Z

0x19 - Sensor Fusion Module

The Module Opcode is 0x19.

The Sensor Fusion Module uses the BOSCH sensor fusion algorithm to combine data from the accelerometer, gyroscope, and magnetometer into meaningful orientation data. It provides several output types including quaternions, Euler angles, gravity vectors, and linear acceleration (acceleration without gravity).

The sensor fusion algorithm runs entirely on the MetaWear and outputs calibrated, processed orientation data. The module must be configured with a fusion mode that determines which sensors are used and which outputs are available.

The fusion modes are:

• Mode 0x01: NDOF (Nine Degrees of Freedom) - Uses accelerometer, gyroscope, and magnetometer. All outputs available.
• Mode 0x02: IMU Plus - Uses accelerometer and gyroscope only. Quaternion, Euler, gravity, and linear acceleration outputs available.
• Mode 0x03: Compass - Uses accelerometer and magnetometer. Heading output available.
• Mode 0x04: M4G - Uses accelerometer and magnetometer with gyroscope simulation. Lower power than NDOF.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Enable	0x01	RW	1	1	Byte 0: Enable (0 \= disable, 1 \= enable sensor fusion)
Mode	0x02	RW	4	4	Byte 0: Fusion Mode (uint8_t, 1 \= NDOF, 2 \= IMU Plus, 3 \= Compass, 4 \= M4G) Byte 1: Acc Range (uint8_t) Byte 2: Gyro Range (uint8_t) Byte 3: Reserved
Output Enable	0x03	RW	2	1	Write: Byte 0: Enable Bit Mask Byte 1: Disable Bit Mask (Bit 0: Corrected Acc, Bit 1: Corrected Gyro, Bit 2: Corrected Mag, Bit 3: Quaternion, Bit 4: Euler, Bit 5: Gravity, Bit 6: Linear Acc) Read: Byte 0: Enable Bit Mask
Corrected Acc	0x04	N		12	Corrected accelerometer data. Notify: Byte 0-3: X: float Byte 4-7: Y: float Byte 8-11: Z: float (in units of g)
Corrected Gyro	0x05	N		12	Corrected gyroscope data. Notify: Byte 0-3: X: float Byte 4-7: Y: float Byte 8-11: Z: float (in units of °/s)
Corrected Mag	0x06	N		12	Corrected magnetometer data. Notify: Byte 0-3: X: float Byte 4-7: Y: float Byte 8-11: Z: float (in units of µT)
Quaternion	0x07	N		16	Orientation as quaternion. Notify: Byte 0-3: W: float Byte 4-7: X: float Byte 8-11: Y: float Byte 12-15: Z: float
Euler Angles	0x08	N		12	Orientation as Euler angles. Notify: Byte 0-3: Heading / Yaw: float (°) Byte 4-7: Pitch: float (°) Byte 8-11: Roll: float (°)
Gravity Vector	0x09	N		12	Gravity direction vector. Notify: Byte 0-3: X: float Byte 4-7: Y: float Byte 8-11: Z: float (in units of g)
Linear Acc	0x0A	N		12	Linear acceleration (without gravity). Notify: Byte 0-3: X: float Byte 4-7: Y: float Byte 8-11: Z: float (in units of g)
Calibration State	0x0B	R		3	Byte 0: Accelerometer Calibration Accuracy (uint8_t, 0 \= unreliable, 3 \= high) Byte 1: Gyroscope Calibration Accuracy (uint8_t) Byte 2: Magnetometer Calibration Accuracy (uint8_t)
Acc Cal Data	0x0C	RW	18	18	Accelerometer calibration data for save/restore across sessions
Gyro Cal Data	0x0D	RW	18	18	Gyroscope calibration data for save/restore across sessions
Mag Cal Data	0x0E	RW	18	18	Magnetometer calibration data for save/restore across sessions
Reset Orientation	0x0F	W			No value required - Resets the orientation to the current position

Fusion Mode Details

Each fusion mode uses a different combination of sensors and produces data at different rates:

Mode	Enum	Sensors Used	Acc Rate	Gyro Rate	Mag Rate	Orientation Type
NDoF	0x01	Accelerometer, Gyro, Mag	100 Hz	100 Hz	25 Hz	Absolute
IMU Plus	0x02	Accelerometer, Gyro	100 Hz	100 Hz	N/A	Relative
Compass	0x03	Accelerometer, Mag	25 Hz	N/A	25 Hz	Absolute
M4G	0x04	Accelerometer, Mag	50 Hz	N/A	50 Hz	Relative

NDoF (Nine Degrees of Freedom) calculates absolute orientation from all three sensors. It provides fast output with high robustness against magnetic field distortions. Fast Magnetometer calibration is enabled in this mode. After magnetic calibration is complete, heading reads 0° when facing magnetic north.

IMU Plus calculates relative orientation from the accelerometer and gyroscope. It provides high output data rate but heading will drift over time because no magnetometer is used for correction. Best for short-duration applications.

Compass calculates geographic direction by combining gravity sensing (accelerometer) with magnetic field measurement. Accuracy depends on the stability of the surrounding magnetic field. Requires calibration.

M4G (Magnet for Gyroscope) is similar to IMU Plus but detects rotation via magnetometer instead of gyroscope. This results in lower power consumption and no gyroscope drift, but accuracy depends on the surrounding magnetic field. No magnetometer calibration is required in this mode.

When using the sensor fusion module, the underlying accelerometer, gyroscope, and magnetometer are automatically configured by the fusion algorithm. Do not configure these sensors separately via their individual module registers while sensor fusion is active.

Calibration

The sensor fusion algorithm performs automatic background calibration of all sensors. This cannot be disabled. The Calibration State register (0x0B) reports the accuracy of each sensor's calibration on a scale from 0 (unreliable) to 3 (high accuracy). A device is considered fully calibrated when all three sensors report accuracy 3.

To calibrate: lay the device on a flat surface and rotate it in 45-degree intervals while monitoring the calibration state values. Once calibrated, save the calibration offsets via the Cal Data registers (0x0C, 0x0D, 0x0E) and restore them on subsequent connections using boot macros to avoid repeating the calibration.

Nearby magnets, batteries, motors, electronics, jewelry, and steel structures will distort the magnetometer. If the environment cannot be guaranteed magnet-free, avoid NDoF and M4G modes and use IMU Plus instead.

Output Data Guidance

Euler Angles (Heading, Pitch, Roll) are suited for applications where tilt angles remain below ~30° and complete rotations are not required, such as digital compasses or pitch/roll monitoring. When pitch reaches 90°, heading becomes undetermined (gimbal lock).

Quaternions (W, X, Y, Z) are a four-component representation that avoids gimbal lock and can describe any arbitrary 3D orientation. Use quaternions when the device may be oriented freely in space or when measuring complete rotations.

Drift Behavior

In IMU Plus mode, pitch and roll drift are compensated by the accelerometer sensing gravity, but heading drifts over time due to gyroscope integration bias. When the device is stationary, the algorithm detects this and stops integrating gyroscope data to prevent additional drift. For applications requiring stable heading over extended periods (multiple hours), use a mode with magnetometer correction (NDoF or Compass).

The sensor fusion algorithm is optimized for tracking human motion. Under sustained large accelerations (e.g., vehicle cornering), the algorithm may incorrectly interpret the acceleration as gravity. Test the device for your specific use case if high-acceleration environments are expected.

0xFE - Debug Module

The Module Opcode is 0xFE.

The Debug Module provides diagnostic and maintenance commands for the MetaWear. It can be used to reset the device, jump to the bootloader for firmware updates, or trigger a watchdog reset.

Setting	Address	Mode	Wlen	Rlen	Value
Module Info	0x00	R		2	Byte 0: Module Implementation ID: 0 (uint8_t) Byte 1: Module Revision: 0+ (uint8_t)
Reset	0x01	W			No value required - Performs a soft reset of the device
Jump to Bootloader	0x02	W			No value required - Jumps to the bootloader for firmware update (DFU mode)
Disconnect	0x06	W			No value required - Forces a BLE disconnect
Reset After GC	0x05	W			No value required - Resets the device after performing garbage collection on flash
Stack Overflow	0x03	W			No value required - For testing: triggers a stack overflow (debug only)

Board Models

MetaWear boards come in several models, each with different sensor configurations. The board model is determined by reading the Module Info from the Settings Module (0x11) and the Accelerometer Module (0x03) during the discovery process.

Model	Enum Value	Accelerometer	Gyroscope	Magnetometer	Barometer	Temperature	Sensor Fusion
MetaWear R	0	MMA8452Q	No	No	No	On-die	No
MetaWear RG	1	BMI160	BMI160	No	No	On-die	No
MetaWear RPro	2	BMI160	BMI160	BMM150	BMP280	On-die, Thermistor, BMP280	No
MetaWear C	3	MMA8452Q	No	No	No	On-die	No
MetaWear CPro	4	BMI160	BMI160	BMM150	BMP280	On-die, Thermistor, BMP280	No
MetaEnvironment	5	BMI160	BMI160	BMM150	BMP280	On-die, Thermistor, BMP280	No
MetaDetector	6	BMI160	BMI160	No	No	On-die	No
MetaHealth	7	BMI160	BMI160	No	No	On-die	No
MetaTracker	8	BMI160	BMI160	BMM150	BMP280	On-die, Thermistor, BMP280	No
MetaMotion R	9	BMI160	BMI160	BMM150	BMP280	On-die, Thermistor, BMP280	Yes
MetaMotion RL	10	BMI160	BMI160	BMM150	BMP280	On-die, Thermistor, BMP280	Yes
MetaMotion C	11	BMI160	BMI160	BMM150	BMP280	On-die, Thermistor, BMP280	Yes
MetaMotion S	12	BMI270	BMI270	BMM150	BMP280	On-die, Thermistor, BMP280	Yes

The MetaMotion S (MMS) is the newest board and uses the BMI270 IMU. The MetaMotion RL (MMRL) and earlier boards use the BMI160. Older boards (MetaWear R, MetaWear C) use the MMA8452Q accelerometer which has a completely different register set (see the MMA8452Q section below).

Active Board Hardware Specifications

The two currently supported MetaSensor boards are:

Spec	MetaMotion RL (MMRL)	MetaMotion S (MMS)
Battery	100mAh rechargeable Li-Po	100mAh rechargeable Li-Po
Battery Life	1 - 14 days (usage dependent)	8 - 24 days (usage dependent)
Physical Size	17mm x 25mm x 5mm	17mm x 25mm x 5mm
Log Memory	8MB (~0.5M log entries)	512MB (~30M log entries)
Accelerometer	BMI160	BMI270
Gyroscope	BMI160	BMI270
Magnetometer	BMM150	BMM150
Barometer / Temp	BMP280	BMP280
Ambient Light	None	LTR-329ALS-01
Charging	Micro-USB	Micro-USB
MCU	ARM (Nordic nRF52)	ARM (Nordic nRF52)

Streaming sensor data consumes more battery than logging because the active BLE connection draws additional power. When logging, the device can operate disconnected; however, downloading large logs after reconnection can take hours depending on the amount of data stored.

The proximity of the battery to the PCB when the board is enclosed in a case may reduce Bluetooth range.

Datasheets: MetaMotion RL (MMRL) | MetaMotion S (MMS)

Sensor Datasheets: BMI160 | BMI270 | BMM150 | BMP280 | LTR-329ALS-01

Logging Memory Capacity

Each log entry occupies 8 bytes in flash memory. Sensors that produce multi-axis data (e.g., accelerometer XYZ) require multiple log entries per sample. The number of log entries per sample determines how quickly memory fills at a given data rate.

Sensor Output	Log Entries Per Sample	Notes
Accelerometer (XYZ)	2	6 bytes of data split across 2 entries
Gyroscope (XYZ)	2	6 bytes of data split across 2 entries
Magnetometer (XYZ)	2	6 bytes of data split across 2 entries
Temperature	1	Single value
Pressure	1	Single value
Humidity	1	Single value
Ambient Light	1	Single value
Color	2	Multi-channel value
Proximity	1	Single value
Euler Angles	4	Heading, Pitch, Roll as floats
Quaternion	4	W, X, Y, Z as floats
Gravity Vector	3	X, Y, Z as floats
Linear Acceleration	3	X, Y, Z as floats

Log capacity per board model (total log entries):

Model	Log Entries	Approx. Memory	Battery (mAh)
MetaMotion S	67,108,864	512 MB	100
MetaMotion C	1,048,576	8 MB	230
MetaMotion R	1,048,576	8 MB	100
MetaMotion RL	1,048,576	8 MB	100
MetaTracker	262,144	2 MB	600
MetaWear C	7,552	~59 KB	230
MetaWear CPro	7,552	~59 KB	230
MetaEnvironment	7,552	~59 KB	230
MetaDetector	7,552	~59 KB	230
MetaWear R	7,552	~59 KB	100
MetaWear RG	7,552	~59 KB	100
MetaWear RPro	7,552	~59 KB	100

Estimating time to fill log: Time (seconds) = Log Entries / (sum of entries-per-second across all active sensors). For example, logging accelerometer at 100 Hz on an MMS uses 200 entries/sec (100 samples × 2 entries), giving 67,108,864 / 200 = 335,544 seconds ≈ 3.9 days.

Sensor Data Rates

The available output data rates (ODR) for each sensor, configurable via the sensor's Data Config register:

Accelerometer:

Chip	Available ODR (Hz)
BMI160 (MMRL)	12.5, 25, 50, 100, 200, 400, 800
BMI270 (MMS)	12.5, 25, 50, 100, 200, 400, 800
BMA255 (MetaEnv/Det)	15.62, 31.26, 62.5, 125, 250, 500
MMA8452Q (MW R/C)	1.56, 6.25, 12.5, 50, 100, 200, 400, 800

Gyroscope (BMI160 / BMI270): 25, 50, 100, 200, 400, 800 Hz

Magnetometer (BMM150): 10, 15, 20, 25 Hz

Barometer (BMP280): 0.25, 0.50, 0.99, 1.96, 3.82, 7.33, 13.5, 83.3 Hz

Barometer (BME280, MetaTracker): 0.99, 1.96, 3.82, 7.33, 13.5, 31.8, 46.5, 83.3 Hz

Ambient Light (LTR-329ALS-01, MMS only): 0.5, 1, 2, 5, 10 Hz

Temperature: No fixed ODR. Temperature is read on demand or via a timer. Common polling intervals: 1s, 15s, 30s, 1m, 15m, 30m, 1hr.

Sensor Fusion Outputs (Euler, Quaternion, Gravity, Linear Acc): Fixed at 100 Hz (determined by the fusion mode, not independently configurable).

Sensor Power Consumption

Approximate current draw per sensor when active (excluding BLE overhead):

Sensor	Current Draw (mA)
Accelerometer BMI160	0.18
Accelerometer BMI270	0.21
Accelerometer BMA255	0.13
Accelerometer MMA8452Q	0.165
Gyroscope	0.5
Magnetometer	0.5
Temperature	0.01
Pressure (BMP280)	0.0034
Pressure (BME280)	0.0028
Humidity	0.0018
Ambient Light	0.22
Color / Proximity	0.065
Sensor Fusion (any)	0.925

BLE streaming overhead: ~7.5 mA when actively streaming data over Bluetooth. When logging without a BLE connection, this overhead is zero.

Battery life estimate: Battery capacity (mAh) / (BLE overhead + sum of active sensor currents) = hours of operation. For example, an MMS (100 mAh) streaming accelerometer BMI270 (0.21 mA) over BLE: 100 / (7.5 + 0.21) ≈ 13 hours. The same configuration logging (no BLE): 100 / 0.21 ≈ 476 hours ≈ 19.8 days.

Data Processor Filter Configuration

When creating a filter via the Data Processor Module (0x09) Add register (0x02), the filter configuration bytes (bytes 4+) are structured differently for each filter type. This section details the byte layout for each filter.

Passthrough (Type 0x01)

Passes data through, optionally with a count limit or conditional gate.

Byte	Field	Size	Description
0	Mode	3 bits	0 \= Pass All, 1 \= Pass Conditional (block until count > 1), 2 \= Pass Count (pass X samples then stop)
1-2	Value	uint16_t	Count or condition value

State (Set/Reset): Value - uint16_t count or condition.

Counter / Accumulator (Type 0x02)

Counts events or accumulates data values.

Byte	Field	Size	Description
0 [0-1]	Output Length	2 bits	Output data length (0 \= 1 byte, 3 \= 4 bytes)
0 [2-3]	Input Length	2 bits	Input value length (0 \= 1 byte, 3 \= 4 bytes)
0 [4-6]	Mode	3 bits	0 \= Accumulate Values (sum), 1 \= Count Events (increment)

State (Set/Reset): Count Value - uint32_t (4 bytes).

Low Memory Average / Low Pass (Type 0x03)

Computes a running average using a recursive algorithm that uses minimal memory.

Byte	Field	Size	Description
0 [0-1]	Output Length	2 bits	Output data length (0 \= 1 byte, 3 \= 4 bytes)
0 [2-3]	Input Length	2 bits	Input value length (0 \= 1 byte, 3 \= 4 bytes)
0 [5]	Mode	1 bit	0 \= Low pass filter, 1 \= High pass filter (firmware >= 1.2.2)
1	Size	uint8_t	Internal buffer size
2	Count	uint8_t	Depth of average. Non-power-of-2 results in slower software divide.

State (Set/Reset): No parameters - resets the running average.

Pulse Detector (Type 0x04)

Detects pulses (peaks above a threshold for a minimum width) in the input data.

Byte	Field	Size	Description
0	Length	uint8_t	Length of input data in bytes
1	Trigger Mode	uint8_t	Trigger output mode
2	Output Mode	uint8_t	What to output when pulse detected
3-6	Threshold	4 bytes	Minimum value for pulse detection
7-8	Width	uint16_t	Minimum pulse width in samples

Peak Detector (Type 0x05)

Detects local maxima or minima in the input data stream.

Byte	Field	Size	Description
0	Look Ahead	uint8_t	Number of samples to look ahead for a bigger peak
1	Looking For Max	uint8_t	0 \= detect min peaks, 1 \= detect max peaks
2	Extra Peak Width	uint8_t	Number of samples to sum on both sides of the peak (becomes output value)
3-6	Delta	4 bytes	Minimum delta that must occur before a peak is considered
7	Offset	uint8_t	Offset in bytes from beginning of input data
8	Length	uint8_t	Length of input data in bytes
9	Is Signed	uint8_t	0 \= unsigned input, 1 \= signed input

Comparator (Type 0x06)

Compares input data against one or more reference values and only passes data that satisfies the comparison.

Single Comparator (firmware < 1.2.3):

Byte	Field	Size	Description
0	Is Signed	uint8_t	0 \= unsigned comparison, 1 \= signed comparison
1	Operation	uint8_t	0 \= EQ, 1 \= NEQ, 2 \= LT, 3 \= LTE, 4 \= GT, 5 \= GTE
2	(reserved)	uint8_t	Unused
3-6	Reference	4 bytes	Reference value to compare against

Multi-Value Comparator (firmware >= 1.2.3):

Byte	Field	Size	Description
0 [0]	Is Signed	1 bit	0 \= unsigned, 1 \= signed
0 [1-2]	Length	2 bits	Data length encoding
0 [3-5]	Operation	3 bits	0 \= EQ, 1 \= NEQ, 2 \= LT, 3 \= LTE, 4 \= GT, 5 \= GTE
0 [6-7]	Mode	2 bits	0 \= Absolute (return data as-is), 1 \= Reference (return matched ref), 2 \= Zone (return ref index), 3 \= Binary (return 1/0)
1-12	References	12 bytes	Up to 3 reference values (4 bytes each)

RMS / RSS (Type 0x07 / 0x08)

Computes the Root Mean Square (RMS) or Root Sum Square (RSS) of multi-component data (e.g., XYZ accelerometer data into a single magnitude value).

Byte	Field	Size	Description
0 [0-1]	Output Length	2 bits	Output data length
0 [2-3]	Input Length	2 bits	Input component length
0 [4-6]	Count	3 bits	Number of input components (e.g., 3 for XYZ)
0 [7]	Is Signed	1 bit	0 \= unsigned, 1 \= signed
1	Mode	uint8_t	0 \= RMS, 1 \= RSS

Math (Type 0x09)

Performs arithmetic operations on the input data.

Byte	Field	Size	Description
0 [0-1]	Output Length	2 bits	Output data length
0 [2-3]	Input Length	2 bits	Input data length
0 [4]	Is Signed	1 bit	0 \= unsigned, 1 \= signed
1	Operation	uint8_t	See math operations table below
2-5	RHS	4 bytes	Right-hand side operand (little-endian)
6	N Channels	uint8_t	Number of input channels (firmware >= 1.1.0)

The math operations are:

Value	Operation	Formula
1	Add	input + rhs
2	Multiply	input × rhs
3	Divide	input / rhs
4	Modulus	input % rhs
5	Exponent	input ^ rhs
6	Sqrt	sqrt(input)
7	Left Shift	input << rhs
8	Right Shift	input >> rhs
9	Subtract	input - rhs
10	Abs Value	|input|
11	Constant	rhs (replaces input)

Sample Delay (Type 0x0A)

Delays data by a fixed number of samples (FIFO buffer).

Byte	Field	Size	Description
0	Length	uint8_t	Length of each sample in bytes
1	Bin Size	uint8_t	Number of samples to buffer

Threshold (Type 0x0B)

Detects when data crosses a threshold boundary.

Byte	Field	Size	Description
0 [0-1]	Length	2 bits	Data length encoding
0 [2]	Is Signed	1 bit	0 \= unsigned, 1 \= signed
0 [3-5]	Mode	3 bits	0 \= Absolute (output data as-is), 1 \= Binary (output 1 if rising, -1 if falling)
1-4	Boundary	4 bytes	Threshold value
5-6	Hysteresis	uint16_t	Hysteresis value to prevent rapid toggling

Delta (Type 0x0C)

Detects when data changes by a specified magnitude from the last reported value.

Byte	Field	Size	Description
0 [0-1]	Length	2 bits	Data length encoding
0 [2]	Is Signed	1 bit	0 \= unsigned, 1 \= signed
0 [3-5]	Mode	3 bits	0 \= Absolute (output when delta exceeded), 1 \= Differential (output the difference), 2 \= Binary (output 1/-1)
1-4	Magnitude	4 bytes	Minimum change required to trigger output

Time Delay (Type 0x0E)

Periodically passes the latest data sample, effectively downsampling by time.

Byte	Field	Size	Description
0 [0-2]	Length	3 bits	Data length encoding
0 [3-5]	Mode	3 bits	Output mode
1-4	Period	uint32_t	Time period in ms between outputs

Buffer (Type 0x0F)

Stores the latest sample for on-demand retrieval via the State register.

Byte	Field	Size	Description
0 [0-4]	Length	5 bits	Data length in bytes

Packer (Type 0x10)

Packs multiple data samples into a single BLE notification to reduce overhead.

Byte	Field	Size	Description
0 [0-4]	Length	5 bits	Length of each sample in bytes
1 [0-4]	Count	5 bits	Number of samples to pack

Accounter (Type 0x11)

Adds a timestamp or counter to each data sample.

Byte	Field	Size	Description
0 [0-3]	Mode	4 bits	0 \= Add counter, 1 \= Add timestamp
0 [4-5]	Length	2 bits	Account data length
1 [0-3]	Prescale	4 bits	Prescaler for the counter/timer

Type 0x12 - Fuser

Combines data from multiple sources. Waits until all inputs have new data, then outputs the combined result.

Byte	Field	Size	Description
0 [0-3]	Count	4 bits	Number of input sources
1-12	References	12 bytes	Filter IDs of the input sources (up to 3, 4 bytes each)

Workflow Examples

Example: Periodic Temperature Reading

This example uses the Timer Module (0x0C) and the Event Module (0x0A) to read the temperature every 5 seconds.

Step 1: Create a timer with a 5000ms period.

Send: [0x0C, 0x02, 0x88, 0x13, 0x00, 0x00, 0xFF, 0xFF, 0x00]

• 0x0C - Timer module
• 0x02 - Timer Entry register
• 0x88 0x13 0x00 0x00 - Period: 5000ms (uint32_t little-endian)
• 0xFF 0xFF - Repeat count: indefinite
• 0x00 - No delay

The MetaWear responds with the Timer ID (e.g., 0x00).

Step 2: Begin recording an event for this timer.

Send: [0x0A, 0x02, 0x0C, 0x06, 0x00]

• 0x0A - Event module
• 0x02 - Entry register
• 0x0C 0x06 0x00 - Source: Timer Module (0x0C), Notify register (0x06), Timer ID 0

Step 3: Record the command to execute (read temperature).

Send: [0x0A, 0x03, 0x04, 0x81, 0x00]

• 0x0A - Event module
• 0x03 - Cmd Parameters register
• 0x04 0x81 0x00 - The command: read temperature sensor index 0

Step 4: Start the timer.

Send: [0x0C, 0x03, 0x00]

• 0x0C - Timer module, 0x03 - Start register, 0x00 - Timer ID

Now the MetaWear will automatically read and send back the temperature every 5 seconds.

Example: Logging Readout Protocol

The logging readout uses a page-based protocol to reliably transfer large amounts of data over BLE.

Step 1: Enable logging and add a trigger for accelerometer data.

Send: [0x0B, 0x02, 0x03, 0x04, 0x00, 0x06]

• 0x0B - Logging module
• 0x02 - Add Trigger register
• 0x03 0x04 - Source: Accelerometer (0x03), Data Interrupt (0x04)
• 0x00 0x06 - Data offset 0, length 6 bytes

Send: [0x0B, 0x01, 0x01] to enable logging.

Step 2: After some time, initiate readout.

Send: [0x0B, 0x06, 0xFF, 0xFF, 0xFF, 0xFF] to read all entries.

Step 3: Process the page-based readout.

The MetaWear sends log entries via the Readout Notify register (0x07). Each notification contains: Trigger ID, Timestamp (uint32_t), and logged data.

Progress updates arrive via the Readout Progress register (0x08) with the number of entries remaining.

When a page is complete, the Page Completed register (0x0D) fires. The host must confirm receipt by writing to the Page Confirm register (0x0E), which triggers the next page.

This continues until all entries have been transferred and the progress reaches 0.

Example: LED Blink on Button Press

This example uses the Event Module to flash the LED when the button is pressed.

Step 1: Record an event triggered by the switch.

Send: [0x0A, 0x02, 0x01, 0x01, 0x00]

• Source: Switch Module (0x01), Switch State register (0x01)

Step 2: Record the LED play command.

Send: [0x0A, 0x03, 0x02, 0x01, 0x01]

• Command: LED Module (0x02), Play register (0x01), Value 0x01 (play)

Now pressing the button will automatically play the LED pattern.

Settings Module Firmware Revisions

The Settings Module (0x11) has expanded over firmware versions. Not all registers are available on all boards. The module revision (from Module Info) determines which registers are supported:

Register	Address	Min Revision	Notes
Device Name	0x01	All	Available on all firmware versions
Advertising Interval	0x02	All	Available on all firmware versions
TX Power	0x03	All	Available on all firmware versions
Start Advertisement	0x05	All	Available on all firmware versions
Scan Response Packet	0x07	All	Available on all firmware versions
Partial Scan Response	0x08	All	Available on all firmware versions
Connection Parameters	0x09	Rev 1+	MMRL and later
Disconnect Event	0x0A	Rev 1+	MMRL and later
MAC Address	0x0B	Rev 1+	MMRL and later
Battery State	0x0C	Rev 1+	MMRL and later; MMS has charger support
Power Status	0x11	Rev 5+	MMS only - USB cable detection
Charge Status	0x12	Rev 5+	MMS only - charging state
Whitelist Filter Mode	0x13	Rev 5+	MMS only
Whitelist Addresses	0x14	Rev 5+	MMS only
3V Power	0x1C	Rev 5+	MMS only - 3.3V regulator control
Force 1M PHY	0x1D	Rev 5+	MMS only - force Bluetooth 1M PHY

Key firmware version thresholds:

• Revision 1 (MMRL): Added connection parameters, disconnect events, MAC address, and battery state
• Revision 5 (MMS): Added power/charge monitoring, whitelist management, 3V regulator control, and PHY selection

The multi-value comparator in the Data Processor Module also has a firmware dependency: the Multi-Value Comparator mode (with Zone and Binary output modes) requires firmware >= 1.2.3.

Error and Status Codes

The MetaWear SDK defines the following status codes. While these are SDK-level codes (not sent over BLE), they indicate common error conditions that hosts should handle:

Code	Name	Value	Description
OK	STATUS_OK	0	Operation completed successfully
WARN	WARNING_UNEXPECTED_SENSOR_DATA	1	Received sensor data that does not match any known subscription
WARN	WARNING_INVALID_PROCESSOR_TYPE	2	Attempted to modify a processor with the wrong type-specific function
ERR	ERROR_UNSUPPORTED_PROCESSOR	4	Attempted to create a processor type not supported by the firmware
WARN	WARNING_INVALID_RESPONSE	8	Received a response that does not match any pending request
ERR	ERROR_TIMEOUT	16	A command or read operation timed out waiting for a response
ERR	ERROR_SERIALIZATION_FORMAT	32	Board state deserialization failed due to format mismatch
ERR	ERROR_ENABLE_NOTIFY	64	Failed to enable BLE notifications on the Notification Characteristic

At the BLE protocol level, error conditions typically manifest as:

• No response: The module opcode or register address is invalid, or the module is not present on the board. Always use the Module Discovery process to verify module availability before sending commands.
• Unexpected data length: The response contains fewer or more bytes than expected. This can happen when reading a register that requires specific input parameters (e.g., temperature sensor index).
• Stale data: Notifications may arrive for previously subscribed data sources after a reconnect. Clear subscriptions and re-subscribe after each connection.

XYZ Axis Orientation

When interpreting accelerometer, gyroscope, and magnetometer data, the axis orientation depends on the IMU chip mounted on the board. With the board positioned face-up and the USB port pointing away from you:

For BMI160 (MMRL and earlier boards) and BMI270 (MMS):

• X-axis: Points to the right (positive direction)
• Y-axis: Points upward / away from you (positive direction)
• Z-axis: Points out of the board face, toward you (positive direction)

This follows a right-hand coordinate system. When the board is lying flat on a table face-up, the Z-axis accelerometer reading should be approximately +1g (9.81 m/s²) due to gravity.

The magnetometer (BMM150) follows the same axis convention as the IMU.

Refer to the BMI160 datasheet or BMI270 datasheet for the full axis orientation diagrams.

MAC Address and BLE Advertising

Each MetaSensor has a unique 6-byte MAC address (e.g., F1:4A:45:90:AC:9D) that serves as its identifier. The MAC address is available in three ways:

1. BLE Advertising Packet: The MAC is included in the device's advertising data and can be read during scanning before establishing a connection.
2. Settings Module Register: On MMRL and later boards (Settings Module revision 1+), the MAC address can be read via register 0x0B of the Settings Module (0x11).
3. Physical Label: The MAC is printed on a sticker on the back of the device.

Platform Note: On Android and Windows, the MAC address is directly accessible from the BLE scan callback. On iOS, Apple obfuscates the MAC address in advertising packets and replaces it with an auto-generated CBUUID. To retrieve the actual MAC on iOS, use the Settings Module register 0x0B after establishing a connection, or read it from the custom advertising data in the MetaWear advertising packet.