ICM426XX - Disable AFSR

src/main/drivers/accgyro/accgyro_spi_icm426xx.c

@@ -48,6 +48,11 @@
 #define ICM426XX_BANK_SELECT3                       0x03
 #define ICM426XX_BANK_SELECT4                       0x04
 
+// Fix for stalls in gyro output. See https://github.com/ArduPilot/ardupilot/pull/25332 ; https://github.com/betaflight/betaflight/pull/13132
+#define ICM426XX_INTF_CONFIG1                       0x4D
+#define ICM426XX_INTF_CONFIG1_AFSR_MASK             0xC0
+#define ICM426XX_INTF_CONFIG1_AFSR_DISABLE          0x40
+
 #define ICM426XX_RA_PWR_MGMT0                       0x4E  // User Bank 0
 #define ICM426XX_PWR_MGMT0_ACCEL_MODE_LN            (3 << 0)
 #define ICM426XX_PWR_MGMT0_GYRO_MODE_LN             (3 << 2)
@@ -284,13 +289,20 @@ void icm426xxGyroInit(gyroDev_t *gyro)
 
     spiBusWriteRegister(&gyro->bus, ICM426XX_RA_INT_SOURCE0, ICM426XX_UI_DRDY_INT1_EN_ENABLED);
 
-    uint8_t intConfig1Value = spiReadRegMsk(&gyro->bus, ICM426XX_RA_INT_CONFIG1);
+    uint8_t intConfig1Value = spiBusReadRegister(&gyro->bus, ICM426XX_RA_INT_CONFIG1);
     // Datasheet says: "User should change setting to 0 from default setting of 1, for proper INT1 and INT2 pin operation"
     intConfig1Value &= ~(1 << ICM426XX_INT_ASYNC_RESET_BIT);
     intConfig1Value |= (ICM426XX_INT_TPULSE_DURATION_8 | ICM426XX_INT_TDEASSERT_DISABLED);
 
     spiBusWriteRegister(&gyro->bus, ICM426XX_RA_INT_CONFIG1, intConfig1Value);
 
+    // Disable AFSR to prevent stalls in gyro output
+    // ICM426XX_INTF_CONFIG1 location in user bank 0
+    uint8_t intfConfig1Value = spiBusReadRegister(&gyro->bus, ICM426XX_INTF_CONFIG1);
+    intfConfig1Value &= ~ICM426XX_INTF_CONFIG1_AFSR_MASK;
+    intfConfig1Value |= ICM426XX_INTF_CONFIG1_AFSR_DISABLE;
+    spiBusWriteRegister(&gyro->bus, ICM426XX_INTF_CONFIG1, intfConfig1Value);
+
     // Turn on gyro and acc on again so ODR and FSR can be configured
     turnGyroAccOn(gyro);
 

src/main/drivers/bus_spi.c

@@ -272,7 +272,8 @@ uint16_t spiCalculateDivider(uint32_t freq)
     return divisor;
 }
 
-// Wait for bus to become free, then read a byte of data where the register is ORed with 0x80
+// Wait for bus to become free, then read a byte of data where the register is bitwise OR'ed with 0x80
+// EmuFlight codebase is old.  Bitwise or 0x80 is redundant here as spiBusReadRegister already contains such.
 uint8_t spiReadRegMsk(const busDevice_t *bus, uint8_t reg)
 {
     return spiBusReadRegister(bus, reg | 0x80);