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fix(icm20948): Fix endianness and scaling of magnetometer data #597

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Merged
finger563 merged 1 commit into from
Feb 7, 2026
Merged

fix(icm20948): Fix endianness and scaling of magnetometer data #597

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18 changes: 14 additions & 4 deletions components/icm20948/src/icm20948.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -698,9 +698,9 @@ Icm20948<I>::Value Icm20948<I>::read_magnetometer(std::error_code &ec) {
}
float sensitivity = get_magnetometer_sensitivity();
Value value = {
static_cast<float>(raw.x) / sensitivity,
static_cast<float>(raw.y) / sensitivity,
static_cast<float>(raw.z) / sensitivity,
static_cast<float>(raw.x) * sensitivity,
static_cast<float>(raw.y) * sensitivity,
static_cast<float>(raw.z) * sensitivity,
};
// update values
mag_values_ = value;
Expand Down Expand Up @@ -1021,7 +1021,17 @@ Icm20948<I>::RawValue Icm20948<I>::get_gyroscope_raw(std::error_code &ec) {

template <espp::icm20948::Interface I>
Icm20948<I>::RawValue Icm20948<I>::get_magnetometer_raw(std::error_code &ec) {
return get_raw(RegisterBank0::MAG_DATA, ec);
// the magnetometer data is read through the I2C master, but it has a
// different endianess than the accelerometer and gyroscope data.
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Copilot AI Feb 8, 2026

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Typo in comment: “endianess” should be “endianness”.

Suggested change
// different endianess than the accelerometer and gyroscope data.
// different endianness than the accelerometer and gyroscope data.

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auto raw_mag = get_raw(RegisterBank0::MAG_DATA, ec);
if (ec) {
return {0, 0, 0};
}
return {
static_cast<int16_t>(((raw_mag.x & 0xFF00) >> 8) | ((raw_mag.x & 0xFF) << 8)),
static_cast<int16_t>(((raw_mag.y & 0xFF00) >> 8) | ((raw_mag.y & 0xFF) << 8)),
static_cast<int16_t>(((raw_mag.z & 0xFF00) >> 8) | ((raw_mag.z & 0xFF) << 8)),
};
Comment on lines +1030 to +1034
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Copilot AI Feb 8, 2026

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The manual byte-swap logic is duplicated for x/y/z and is a bit hard to read/maintain. Consider extracting a small helper (e.g., a local lambda) that swaps a 16-bit value (ideally operating on uint16_t) and reuse it for each axis to reduce repetition and avoid subtle signed/bitshift pitfalls.

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}

template <espp::icm20948::Interface I>
Expand Down