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switch: Fix gyro ZRO handling in IMU sensor updates #15860

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switch: Fix gyro ZRO handling in IMU sensor updates #15860

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e52e681
joystick: Fix pointer sequencing in Switch Pro Controller user IMU ca…
Jun 20, 2026
84b7408
joystick: Apply Gyroscope Zero-Rate Offset (ZRO) subtraction to live …
Jun 20, 2026
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43 changes: 32 additions & 11 deletions src/joystick/hidapi/SDL_hidapi_switch.c
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Original file line number Diff line number Diff line change
Expand Up @@ -351,6 +351,10 @@ typedef struct
float fGyroScaleX;
float fGyroScaleY;
float fGyroScaleZ;

Sint16 sGyroOffsetX;
Sint16 sGyroOffsetY;
Sint16 sGyroOffsetZ;
} m_IMUScaleData;
} SDL_DriverSwitch_Context;

Expand Down Expand Up @@ -1113,18 +1117,27 @@ static bool LoadIMUCalibration(SDL_DriverSwitch_Context *ctx)
// Check for user calibration data. If it's present and set, it'll override the factory settings
readParams.unAddress = k_unSPIIMUUserScaleStartOffset;
readParams.ucLength = k_unSPIIMUUserScaleLength;
if (WriteSubcommand(ctx, k_eSwitchSubcommandIDs_SPIFlashRead, (uint8_t *)&readParams, sizeof(readParams), &reply) && (pIMUScale[0] | pIMUScale[1] << 8) == 0xA1B2) {
pIMUScale = reply->spiReadData.rgucReadData;
if (WriteSubcommand(ctx, k_eSwitchSubcommandIDs_SPIFlashRead, (uint8_t *)&readParams, sizeof(readParams), &reply)) {
Uint8 *pUserIMUScale = reply->spiReadData.rgucReadData;

if ((pUserIMUScale[0] | (pUserIMUScale[1] << 8)) == 0xA1B2) {
pIMUScale = pUserIMUScale;

sAccelRawX = (pIMUScale[3] << 8) | pIMUScale[2];
sAccelRawY = (pIMUScale[5] << 8) | pIMUScale[4];
sAccelRawZ = (pIMUScale[7] << 8) | pIMUScale[6];
sAccelRawX = (pIMUScale[3] << 8) | pIMUScale[2];
sAccelRawY = (pIMUScale[5] << 8) | pIMUScale[4];
sAccelRawZ = (pIMUScale[7] << 8) | pIMUScale[6];

sGyroRawX = (pIMUScale[15] << 8) | pIMUScale[14];
sGyroRawY = (pIMUScale[17] << 8) | pIMUScale[16];
sGyroRawZ = (pIMUScale[19] << 8) | pIMUScale[18];
sGyroRawX = (pIMUScale[15] << 8) | pIMUScale[14];
sGyroRawY = (pIMUScale[17] << 8) | pIMUScale[16];
sGyroRawZ = (pIMUScale[19] << 8) | pIMUScale[18];
}
}

// Gyro zero-rate offset
ctx->m_IMUScaleData.sGyroOffsetX = sGyroRawX;
ctx->m_IMUScaleData.sGyroOffsetY = sGyroRawY;
ctx->m_IMUScaleData.sGyroOffsetZ = sGyroRawZ;

// Accelerometer scale
ctx->m_IMUScaleData.fAccelScaleX = SWITCH_ACCEL_SCALE_MULT / ((float)sAccelSensCoeffX - (float)sAccelRawX) * SDL_STANDARD_GRAVITY;
ctx->m_IMUScaleData.fAccelScaleY = SWITCH_ACCEL_SCALE_MULT / ((float)sAccelSensCoeffY - (float)sAccelRawY) * SDL_STANDARD_GRAVITY;
Expand All @@ -1147,6 +1160,10 @@ static bool LoadIMUCalibration(SDL_DriverSwitch_Context *ctx)
ctx->m_IMUScaleData.fGyroScaleX = gyroScale;
ctx->m_IMUScaleData.fGyroScaleY = gyroScale;
ctx->m_IMUScaleData.fGyroScaleZ = gyroScale;

ctx->m_IMUScaleData.sGyroOffsetX = 0;
ctx->m_IMUScaleData.sGyroOffsetY = 0;
ctx->m_IMUScaleData.sGyroOffsetZ = 0;
}
return true;
}
Expand Down Expand Up @@ -2362,9 +2379,13 @@ static void SendSensorUpdate(Uint64 timestamp, SDL_Joystick *joystick, SDL_Drive
* users will want consistent axis mappings across devices.
*/
if (type == SDL_SENSOR_GYRO || type == SDL_SENSOR_GYRO_L || type == SDL_SENSOR_GYRO_R) {
data[0] = -(ctx->m_IMUScaleData.fGyroScaleY * (float)values[1]);
data[1] = ctx->m_IMUScaleData.fGyroScaleZ * (float)values[2];
data[2] = -(ctx->m_IMUScaleData.fGyroScaleX * (float)values[0]);
const float gyroX = (float)(values[0] - ctx->m_IMUScaleData.sGyroOffsetX);
const float gyroY = (float)(values[1] - ctx->m_IMUScaleData.sGyroOffsetY);
const float gyroZ = (float)(values[2] - ctx->m_IMUScaleData.sGyroOffsetZ);

data[0] = -(ctx->m_IMUScaleData.fGyroScaleY * gyroY);
data[1] = ctx->m_IMUScaleData.fGyroScaleZ * gyroZ;
data[2] = -(ctx->m_IMUScaleData.fGyroScaleX * gyroX);
} else {
data[0] = -(ctx->m_IMUScaleData.fAccelScaleY * (float)values[1]);
data[1] = ctx->m_IMUScaleData.fAccelScaleZ * (float)values[2];
Expand Down