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QMI8658C IMU implementation fixes #523

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QMI8658C IMU implementation fixes #523

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8c9367c
fix buffer vs data length passing to i2c read_mem
dudasdavid Jan 17, 2026
66181a8
fix accel and gyro range register values
dudasdavid Jan 17, 2026
2fe42fd
proper calculation for acceleration in m/s2 and for gyro in deg/s
dudasdavid Jan 17, 2026
f18720f
move ranges and rates to arguments of imu instance
dudasdavid Jan 17, 2026
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67 changes: 39 additions & 28 deletions api_drivers/common_api_drivers/imu_sensor/qmi8658c.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
from micropython import const # NOQA
import imu_sensor_framework # NOQA

_ONE_G = const(9.807)

_VERSION_REG = const(0x0)
_REVISION_REG = const(0x1)
Expand Down Expand Up @@ -32,20 +33,22 @@ def _decode_settings(value):
def _encode_setting(rnge, rate):
return ((rnge & 0x7) << 4) | (rate & 0xF)

def _int16(value):
return value - 0x10000 if value & 0x8000 else value

ACCEL_RANGE_2 = const(0) # +/- 2g
ACCEL_RANGE_4 = const(0x10) # +/- 4g
ACCEL_RANGE_8 = const(0x20) # +/- 8g (default value)
ACCEL_RANGE_16 = const(0x30) # +/- 16g
ACCEL_RANGE_4 = const(1) # +/- 4g
ACCEL_RANGE_8 = const(2) # +/- 8g (default value)
ACCEL_RANGE_16 = const(3) # +/- 16g

GYRO_RANGE_16 = const(0) # +/- 16 deg/s
GYRO_RANGE_32 = const(0x10) # +/- 32 deg/s
GYRO_RANGE_64 = const(0x20) # +/- 64 deg/s
GYRO_RANGE_128 = const(0x30) # +/- 128 deg/s
GYRO_RANGE_256 = const(0x40) # +/- 256 deg/s (default value)
GYRO_RANGE_512 = const(0x50) # +/- 512 deg/s
GYRO_RANGE_1024 = const(0x60) # +/- 1024 deg/s
GYRO_RANGE_2048 = const(0x70) # +/- 2048 deg/s
GYRO_RANGE_32 = const(1) # +/- 32 deg/s
GYRO_RANGE_64 = const(2) # +/- 64 deg/s
GYRO_RANGE_128 = const(3) # +/- 128 deg/s
GYRO_RANGE_256 = const(4) # +/- 256 deg/s (default value)
GYRO_RANGE_512 = const(5) # +/- 512 deg/s
GYRO_RANGE_1024 = const(6) # +/- 1024 deg/s
GYRO_RANGE_2048 = const(7) # +/- 2048 deg/s

ACCEL_RATE_8000_HZ = const(0)
ACCEL_RATE_4000_HZ = const(1)
Expand Down Expand Up @@ -79,14 +82,14 @@ def _encode_setting(rnge, rate):
class QMI8658C(imu_sensor_framework.IMUSensorFramework):

def _read_reg(self, reg):
self._device.read_mem(reg, self._rx_mv[:1])
self._device.read_mem(reg, buf=self._rx_mv[:1])
return self._rx_buf[0]

def _write_reg(self, reg, data):
self._tx_buf[0] = data
self._device.write_mem(reg, self._tx_mv[:1])

def __init__(self, device, delay_between_samples=100):
def __init__(self, device, accel_range=ACCEL_RANGE_8, accel_rate=ACCEL_RATE_125_HZ, gyro_range=GYRO_RANGE_256, gyro_rate=GYRO_RATE_125_HZ, delay_between_samples=100):

super().__init__(device, 0.0, delay_between_samples)
self._device = device
Expand All @@ -98,15 +101,15 @@ def __init__(self, device, delay_between_samples=100):
if self._read_reg(_VERSION_REG) != 0x05:
raise RuntimeError("Failed to find QMI8658C")

self._accel_range = ACCEL_RANGE_8
self._accel_rate = ACCEL_RATE_125_HZ
self._accel_range = accel_range
self._accel_rate = accel_rate

self._gyro_range = GYRO_RANGE_256
self._gyro_rate = GYRO_RATE_125_HZ
self._gyro_range = gyro_range
self._gyro_rate = gyro_rate

self._write_reg(_CONFIG2_REG, 0x60)
self._write_reg(_ACCEL_SETTING_REG, _encode_setting(ACCEL_RANGE_8, ACCEL_RATE_125_HZ))
self._write_reg(_GYRO_SETTING_REG, _encode_setting(GYRO_RANGE_256, GYRO_RATE_125_HZ))
self._write_reg(_ACCEL_SETTING_REG, _encode_setting(self._accel_range, self._accel_rate))
self._write_reg(_GYRO_SETTING_REG, _encode_setting(self._gyro_range, self._gyro_rate))

self._write_reg(_CONFIG5_REG, 0x00) # No magnetometer
self._write_reg(_CONFIG6_REG, 0x00) # Disables Gyroscope And Accelerometer Low-Pass Filter
Expand Down Expand Up @@ -151,34 +154,42 @@ def gyro_rate(self, value):

@property
def timestamp(self) -> int:
self._device.read_mem(_TIME_REG, self._rx_mv[:3])
self._device.read_mem(_TIME_REG, buf=self._rx_mv[:3])
return self._rx_buf[0] + (self._rx_buf[1] << 8) + (self._rx_buf[2] << 16)

@property
def temperature(self) -> float:
"""Chip temperature"""
self._device.read_mem(_TEMP_REG, self._rx_mv[:2])
self._device.read_mem(_TEMP_REG, buf=self._rx_mv[:2])
temp = self._rx_buf[0] / 256 + self._rx_buf[1]
return temp

def _get_accelerometer(self):
self._device.read_mem(_ACCEL_REG, self._rx_mv[:6])
self._device.read_mem(_ACCEL_REG, buf=self._rx_mv[:6])

buf = self._rx_buf

x = buf[0] << 8 | buf[1]
y = buf[2] << 8 | buf[3]
z = buf[4] << 8 | buf[5]
x_raw = buf[1] << 8 | buf[0]
y_raw = buf[3] << 8 | buf[2]
z_raw = buf[5] << 8 | buf[4]

x = float(_int16(x_raw)) / (1 << (14 - self._accel_range)) * _ONE_G
y = float(_int16(y_raw)) / (1 << (14 - self._accel_range)) * _ONE_G
z = float(_int16(z_raw)) / (1 << (14 - self._accel_range)) * _ONE_G

return x, y, z

def _get_gyrometer(self):
self._device.read_mem(_GYRO_REG, self._rx_mv[:6])
self._device.read_mem(_GYRO_REG, buf=self._rx_mv[:6])
buf = self._rx_buf

x = buf[0] << 8 | buf[1]
y = buf[2] << 8 | buf[3]
z = buf[4] << 8 | buf[5]
x_raw = buf[1] << 8 | buf[0]
y_raw = buf[3] << 8 | buf[2]
z_raw = buf[5] << 8 | buf[4]

x = float(_int16(x_raw)) / (1 << (11 - self._gyro_range))
y = float(_int16(y_raw)) / (1 << (11 - self._gyro_range))
z = float(_int16(z_raw)) / (1 << (11 - self._gyro_range))

return x, y, z

Expand Down
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