Support MPU925x internal magnetometer over I2C

src/main/cli/settings.c

@@ -149,7 +149,7 @@ const char * const lookupTableBaroHardware[] = {
 #if defined(USE_SENSOR_NAMES) || defined(USE_MAG)
 // sync with magSensor_e
 const char * const lookupTableMagHardware[] = {
-    "AUTO", "NONE", "HMC5883", "AK8975", "AK8963", "QMC5883", "LIS3MDL"
+    "AUTO", "NONE", "HMC5883", "AK8975", "AK8963", "QMC5883", "LIS3MDL", "MAG_MPU925X_AK8963"
 };
 #endif
 #if defined(USE_SENSOR_NAMES) || defined(USE_RANGEFINDER)

src/main/drivers/compass/compass_mpu925x_ak8963.c

@@ -0,0 +1,77 @@
+/*
+ * This file is part of Cleanflight.
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "platform.h"
+
+#include "drivers/bus.h"
+#include "drivers/sensor.h"
+#include "drivers/system.h"
+#include "drivers/time.h"
+
+#include "drivers/accgyro/accgyro_mpu.h"
+
+#include "drivers/compass/compass.h"
+#include "drivers/compass/compass_ak8963.h"
+#include "drivers/compass/compass_mpu925x_ak8963.h"
+
+#if defined(USE_MAG_MPU925X_AK8963)
+
+#define MPU925X_I2C_ADDRESS             0x68
+#define AK8963_MAG_I2C_ADDRESS          0x0C
+#define MPU9250_BIT_RESET               0x80
+
+static bool mpu925xDeviceDetect(busDevice_t * dev)
+{
+    busWriteRegister(dev, MPU_RA_PWR_MGMT_1, MPU9250_BIT_RESET);
+    delay(150);
+    switch (busReadRegister(dev, MPU_RA_WHO_AM_I)) {
+        case MPU9250_WHO_AM_I_CONST:
+        case MPU9255_WHO_AM_I_CONST:
+            return true;
+        default:
+            return false;
+    }
+}
+
+bool mpu925Xak8963CompassDetect(magDev_t * mag)
+{
+    busDevice_t *busdev = &mag->busdev;
+    busdev->busdev_u.i2c.address = MPU925X_I2C_ADDRESS;
+    busDeviceRegister(busdev);
+    if (busdev == NULL || !mpu925xDeviceDetect(busdev)) {
+        return false;
+    }
+    // set bypass mode on mpu9250
+    busWriteRegister(busdev, MPU_RA_INT_PIN_CFG, 0x02);
+    delay(150);
+    // now we have ak8963 alike on the bus
+    busdev->busdev_u.i2c.address = AK8963_MAG_I2C_ADDRESS;
+    busDeviceRegister(busdev);
+    if(!ak8963Detect(mag)) {
+        // if ak8963 is not detected, reset the MPU to disable bypass mode
+        busdev->busdev_u.i2c.address = MPU925X_I2C_ADDRESS;
+        busWriteRegister(busdev, MPU_RA_PWR_MGMT_1, MPU9250_BIT_RESET);
+        return false;
+    } else {
+        return true;
+    }
+}
+
+#endif

src/main/drivers/compass/compass_mpu925x_ak8963.h

@@ -0,0 +1,20 @@
+/*
+ * This file is part of Cleanflight.
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+bool mpu925Xak8963CompassDetect(magDev_t *mag);

src/main/sensors/compass.c

@@ -38,8 +38,10 @@
 #include "drivers/compass/compass_ak8963.h"
 #include "drivers/compass/compass_fake.h"
 #include "drivers/compass/compass_hmc5883l.h"
-#include "drivers/compass/compass_qmc5883l.h"
 #include "drivers/compass/compass_lis3mdl.h"
+#include "drivers/compass/compass_mpu925x_ak8963.h"
+#include "drivers/compass/compass_qmc5883l.h"
+
 #include "drivers/io.h"
 #include "drivers/light_led.h"
 #include "drivers/time.h"
@@ -267,6 +269,18 @@ bool compassDetect(magDev_t *dev, uint8_t *alignment)
         break;
     }
 
+    // MAG_MPU925X_AK8963 is an MPU925x configured as I2C passthrough to the built-in AK8963 magnetometer
+    // Passthrough mode disables the gyro/acc part of the MPU, so we only want to detect this sensor if mag_hardware was explicitly set to MAG_MPU925X_AK8963
+#ifdef USE_MAG_MPU925X_AK8963
+    if(compassConfig()->mag_hardware == MAG_MPU925X_AK8963){
+        if (mpu925Xak8963CompassDetect(dev)) {
+            magHardware = MAG_MPU925X_AK8963;
+        } else {
+            return false;
+        }
+    }
+#endif
+
     if (magHardware == MAG_NONE) {
         return false;
     }

src/main/sensors/compass.h

@@ -36,7 +36,8 @@ typedef enum {
     MAG_AK8975 = 3,
     MAG_AK8963 = 4,
     MAG_QMC5883 = 5,
-    MAG_LIS3MDL = 6
+    MAG_LIS3MDL = 6,
+    MAG_MPU925X_AK8963 = 7
 } magSensor_e;
 
 typedef struct mag_s {

src/main/target/STM32_UNIFIED/target.h

@@ -178,6 +178,7 @@
 #define USE_MAG_QMC5883
 #define USE_MAG_LIS3MDL
 #define USE_MAG_AK8963
+#define USE_MAG_MPU925X_AK8963
 #define USE_MAG_SPI_AK8963
 
 #define USE_BARO