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IMU Gyro Sensor × micro:bit (MakeCode extension)

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The universal I2C edition of the IMU Gyro Sensor works with BBC micro:bit V1 / V2 through the MakeCode extension pxt-mbc-sensors v2 (which speaks MBC I2C protocol v2). Installation and hardware notes (3.3 V, power): micro:bit overview.

SPIKEEV3Arduino I2CmBlockMATRIXmicro:bit

Important

Extension v2 is not yet verified on hardware; block names follow the published release: https://github.com/contactmbcrobot/pxt-mbc-sensors

Wiring

IMU Gyro Sensor × micro:bit
Sensor micro:bit
SDA（RX） P20
SCL（TX） P19
VCC micro:bit 3V (external 5 V recommended on batteries)
GND GND

Reporter blocks

Block Returns Id Meaning
IMU heading [gyro 3D] (°) -32768~32767 ° 01 heading from the 3D quaternion, degrees, 0 at boot/zero, accumulates past 360 (wraps at ±32767, ~91 turns)
IMU heading [fused] (°) -32768~32767 ° 02 3D gyro heading slowly corrected by the magnetometer, degrees, relative to the zero point; may exceed 360
IMU heading [gyro 1D] (°) -32768~32767 ° 03 heading integrated about the yaw axis only, degrees, 0 at boot/zero; may exceed 360
IMU heading [magnetic] (°) -32768~32767 ° 04 tilt-compensated magnetometer heading, degrees, relative to the zero point
IMU turn rate (0.1 °/s) -32768~32767 0.1 dps 05 angular rate about the yaw axis (getYawAxis()), 0.1 deg/s, same sign as the heading
IMU pitch (°) -90~+90 ° 06 elevation of the board's printed X axis above horizontal: +90 pointing up, −90 pointing down, 0 level (from the gravity vector)
IMU pitch rate (0.1 °/s) -32768~32767 0.1 dps 07 angular rate about the board's printed X axis, 0.1 °/s (right-hand rule, CCW seen from +X is positive); this is gyro X, not the derivative of 06
IMU magnetic trust 0~255 08 how much the fusion trusts the magnetometer, 0255 (= 01 × 255)
IMU magnetic disturbance 0~255 0.01° 09 magnetic disturbance level 0~255 (degrees × 100, capped at 255)
IMU face up 0~5 0A which axis points up: 0 +X, 1 +Y, 2 +Z, 3 −X, 4 −Y, 5 −Z (physical axes)
IMU [gyro (0.1 °/s)] axis [X / Y / Z] -32768~32767 0.1 dps 10~12 10 X, 11 Y, 12 Z angular rate, 0.1 deg/s (physical axes, sign-corrected)
IMU [accelerometer (mg)] axis [X / Y / Z] -32768~32767 mg 13~15 13 X, 14 Y, 15 Z acceleration, mg (1000 = 1 g)
IMU [magnetometer (mG)] axis [X / Y / Z] -32768~32767 mG 16~18 16 X, 17 Y, 18 Z magnetic field, mG (milligauss)

More blocks (yes / no, events)

Block Related value
on IMU turned by 90 ° 02
IMU is [still] 05
IMU face up is [+Z] 0A

Command blocks

Block Id Meaning
IMU zero heading E0 zero all four headings (zeroHeadings()); EV3 also accepts the stock gyro-reset WRITE 0x11
IMU calibration [accelerometer start] E1 start accelerometer calibration (= v1 0x20=0x01); F3 b4 = 1 meanwhile; ignored during magnetometer calibration (0B state 3 rejected)
IMU calibration [accelerometer end] E2 finish accelerometer calibration and save to EEPROM (= v1 0x20=0x02); on success the mount axis is re-captured and headings are zeroed once the sensor is level and still (not immediately); rejected if not calibrating (0B state 3); failed check → 0B state 2
IMU calibration [magnetometer start] E3 start magnetometer calibration (= v1 0x20=0x03); F3 b5 = 1 meanwhile; ignored if the magnetometer has failed (0B state 3)
IMU calibration [magnetometer end] E4 finish magnetometer calibration and save to EEPROM (= v1 0x20=0x04); headings zeroed right away on success; rejected if not calibrating (0B state 3); failed check → 0B state 2

Status

bit Name Meaning
b0 ready (ready) always 1
b1 stationary (still) 1 = sensor is stationary
b2 mount axis captured (axisCaptured) 1 = mounting orientation determined (headings zeroed once after first capture)
b3 mount too tilted (mountTilted) 1 = mounted too far from level
b4 accel calibrating (accelCalibrating) 1 between E1 and E2
b5 mag calibrating (magCalibrating) 1 between E3 and E4
b6 fusion initialised (fusionInit) 1 = fused heading is valid
b7 mag auto-cal converged (magAutoCalDone) 1 = magnetometer auto-calibration offsets have converged

JavaScript

if (!(mbc.waitReady(0x6A, 3000))) {
    basic.showIcon(IconNames.No)   // nothing answers: check wiring and power
}
basic.forever(function () {
    basic.showNumber(mbc.imuHeading(MbcImuHeading.Gyro3D))   // gyro 3D heading
    basic.pause(100)
})

Sources and assumptions

Generated by _build/gen-reference.mjs from _build/protocol/imu.json (single source of truth, transcribed from the 2026-10-21 protocol decisions).

  • hw0 = 1（共識 #6）；EV3 模式 4 = [0x6A | 1<<8, 韌體主×100+次, 0, 0]（格式 B 再補 2 個 0），模式 5 改送俯仰角速度（取代 #65 放的 ID）。
  • EV3 鎖住模式 0／1／3 照盤點程式碼：0 = 陀螺 3D、1 = 融合航向、3 = [陀螺 1D, 磁力航向]（INO:213 註解寫反，以程式為準）。
  • 0x22 照 R4 版（出貨版）鎖住：命令 49 = 三個航向 +32768 的「低 byte 在前、高 byte 在後」；盤點檔分析的是主韌體（高在前），主韌體 #67 改成跟 R4 版逐 byte 相同。命令 1012 = 0；0x01、0x0A、0x0F、F1~F4 都觸發航向歸零（刻意，不動）。
  • B-13：E1~E4 加速度計／磁力計校準開始／結束補回（v1 的 0x20 = 01/02/03/04），I2C 定案 §3 只列 E0。busyFlag：E1 → b4、E3 → b5。
  • 俯仰角範圍定案沒寫（韌體尚無現成值，#67 用 atan2 新算），range 先填「°」不給 min/max，韌體做好後再補。
  • 磁力信任度 08 = round(trust×255)，磁場干擾度 09 = round(disturbance×100) 上限 255，朝上的面 0A = 軸號 + 3×負向：公式照盤點 I2C v1 0x34~0x36。
  • 角速度 1012 = round(dps×SIGN×10)、加速度 1315 = mm/s²×1000/9806.65、磁力 1618 = raw×SIGN×4/15：公式照盤點 I2C v1 0x220x24；mBlock 一併有（I2C 定案 §4 共用值表）。
  • 主對話 2026-10-22：06 俯仰角範圍 −90~+90、07 = gyro X（照字面），取自 F5 韌體實作。
  • The extension reads Int16LE and pauses 2 ms after writing the id (D5); with no sensor answering, reporters return 0 and yes / no blocks return false.
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