Add support external clock for gyro ICM42688P (betaflight#13912)

src/main/cli/cli.c

@@ -5141,6 +5141,9 @@ const cliResourceValue_t resourceTable[] = {
 #endif
     DEFW( OWNER_GYRO_EXTI,     PG_GYRO_DEVICE_CONFIG, gyroDeviceConfig_t, extiTag, MAX_GYRODEV_COUNT ),
     DEFW( OWNER_GYRO_CS,       PG_GYRO_DEVICE_CONFIG, gyroDeviceConfig_t, csnTag, MAX_GYRODEV_COUNT ),
+#if defined(USE_GYRO_CLKIN)
+    DEFW( OWNER_GYRO_CLKIN,    PG_GYRO_DEVICE_CONFIG, gyroDeviceConfig_t, clkIn, MAX_GYRODEV_COUNT),
+#endif
 #ifdef USE_USB_DETECT
     DEFS( OWNER_USB_DETECT,    PG_USB_CONFIG, usbDev_t, detectPin ),
 #endif

src/main/drivers/accgyro/accgyro_spi_icm426xx.c

@@ -42,8 +42,10 @@
 #include "drivers/io.h"
 #include "drivers/sensor.h"
 #include "drivers/time.h"
+#include "drivers/pwm_output.h"
 
 #include "sensors/gyro.h"
+#include "pg/gyrodev.h"
 
 // Allows frequency to be set from the compile line EXTRA_FLAGS by adding e.g.
 // -D'ICM426XX_CLOCK=12000000'. If using the configurator this simply becomes
@@ -56,6 +58,8 @@
 #define ICM426XX_MAX_SPI_CLK_HZ ICM426XX_CLOCK
 #endif
 
+#define ICM426XX_CLKIN_FREQ                         32000
+
 #define ICM426XX_RA_REG_BANK_SEL                    0x76
 #define ICM426XX_BANK_SELECT0                       0x00
 #define ICM426XX_BANK_SELECT1                       0x01
@@ -121,6 +125,12 @@
 #define ICM426XX_UI_DRDY_INT1_EN_DISABLED           (0 << 3)
 #define ICM426XX_UI_DRDY_INT1_EN_ENABLED            (1 << 3)
 
+// specific to CLKIN configuration
+#define ICM426XX_INTF_CONFIG5                       0x7B  // User Bank 1
+#define ICM426XX_INTF_CONFIG1_CLKIN                 (1 << 2)
+#define ICM426XX_INTF_CONFIG5_PIN9_FUNCTION_MASK    (3 << 1)   // PIN9 mode config
+#define ICM426XX_INTF_CONFIG5_PIN9_FUNCTION_CLKIN   (2 << 1)   // PIN9 as CLKIN
+
 typedef enum {
     ODR_CONFIG_8K = 0,
     ODR_CONFIG_4K,
@@ -168,10 +178,85 @@ static aafConfig_t aafLUT42605[AAF_CONFIG_COUNT] = {  // see table in section 5.
     [AAF_CONFIG_1962HZ] = { 63, 3968,  3 }, // 995 Hz is the max cutoff on the 42605
 };
 
+static void setUserBank(const extDevice_t *dev, const uint8_t user_bank)
+{
+    spiWriteReg(dev, ICM426XX_RA_REG_BANK_SEL, user_bank & 7);
+}
+
+#if defined(USE_GYRO_CLKIN)
+static pwmOutputPort_t pwmGyroClk = {0};
+
+static bool initExternalClock(const extDevice_t *dev)
+{
+    int cfg;
+    if (&gyro.gyroSensor1.gyroDev.dev == dev) {
+        cfg = 0;
+    } else if (&gyro.gyroSensor2.gyroDev.dev == dev) {
+        cfg = 1;
+    } else {
+        // only gyroSensor<n> device supported
+        return false;
+    }
+    const ioTag_t tag = gyroDeviceConfig(cfg)->clkIn;
+    const IO_t io = IOGetByTag(tag);
+    if (pwmGyroClk.enabled) {
+       // pwm is already taken, but test for shared clkIn pin
+       return pwmGyroClk.io == io;
+    }
+
+    const timerHardware_t *timer = timerAllocate(tag, OWNER_GYRO_CLKIN, RESOURCE_INDEX(cfg));
+    if (!timer) {
+        // Error handling: failed to allocate timer
+        return false;
+    }
+
+    pwmGyroClk.io = io;
+    pwmGyroClk.enabled = true;
+
+    IOInit(io, OWNER_GYRO_CLKIN, RESOURCE_INDEX(cfg));
+    IOConfigGPIOAF(io, IOCFG_AF_PP, timer->alternateFunction);
+
+    const uint32_t clock = timerClock(timer->tim);  // Get the timer clock frequency
+    const uint16_t period = clock / ICM426XX_CLKIN_FREQ;
+
+    // Calculate duty cycle value for 50%
+    const uint16_t value = period / 2;
+
+    // Configure PWM output
+    pwmOutConfig(&pwmGyroClk.channel, timer, clock, period - 1, value - 1, 0);
+
+    // Set CCR value
+    *pwmGyroClk.channel.ccr = value - 1;
+
+    return true;
+}
+
+static void icm426xxEnableExternalClock(const extDevice_t *dev)
+{
+    if (initExternalClock(dev)) {
+        // Switch to Bank 1 and set bits 2:1 in INTF_CONFIG5 (0x7B) to enable CLKIN on PIN9
+        setUserBank(dev, ICM426XX_BANK_SELECT1);
+        uint8_t intf_config5 = spiReadRegMsk(dev, ICM426XX_INTF_CONFIG5);
+        intf_config5 = (intf_config5 & ~ICM426XX_INTF_CONFIG5_PIN9_FUNCTION_MASK) | ICM426XX_INTF_CONFIG5_PIN9_FUNCTION_CLKIN;  // Clear & set bits 2:1 to 0b10 for CLKIN
+        spiWriteReg(dev, ICM426XX_INTF_CONFIG5, intf_config5);
+
+        // Switch to Bank 0 and set bit 2 in RTC_MODE (0x4D) to enable external CLK signal
+        setUserBank(dev, ICM426XX_BANK_SELECT0);
+        uint8_t rtc_mode = spiReadRegMsk(dev, ICM426XX_INTF_CONFIG1);
+        rtc_mode |= ICM426XX_INTF_CONFIG1_CLKIN; // Enable external CLK signal
+        spiWriteReg(dev, ICM426XX_INTF_CONFIG1, rtc_mode);
+    }
+}
+#endif
+
 uint8_t icm426xxSpiDetect(const extDevice_t *dev)
 {
     spiWriteReg(dev, ICM426XX_RA_PWR_MGMT0, 0x00);
 
+#if defined(USE_GYRO_CLKIN)
+    icm426xxEnableExternalClock(dev);
+#endif
+
     uint8_t icmDetected = MPU_NONE;
     uint8_t attemptsRemaining = 20;
     do {
@@ -235,11 +320,6 @@ static void turnGyroAccOn(const extDevice_t *dev)
     delay(1);
 }
 
-static void setUserBank(const extDevice_t *dev, const uint8_t user_bank)
-{
-    spiWriteReg(dev, ICM426XX_RA_REG_BANK_SEL, user_bank & 7);
-}
-
 void icm426xxGyroInit(gyroDev_t *gyro)
 {
     const extDevice_t *dev = &gyro->dev;

src/main/drivers/resource.c

@@ -115,4 +115,5 @@ const char * const ownerNames[OWNER_TOTAL_COUNT] = {
     "SOFTSERIAL_RX",
     "LPUART_TX",
     "LPUART_RX",
+    "GYRO_CLKIN",
 };

src/main/drivers/resource.h

@@ -113,6 +113,7 @@ typedef enum {
     OWNER_SOFTSERIAL_RX,
     OWNER_LPUART_TX,
     OWNER_LPUART_RX,
+    OWNER_GYRO_CLKIN,
     OWNER_TOTAL_COUNT
 } resourceOwner_e;
 

src/main/pg/gyrodev.c

@@ -50,6 +50,14 @@
 #define GYRO_2_EXTI_PIN NONE
 #endif
 
+#ifndef GYRO_1_CLKIN_PIN
+#define GYRO_1_CLKIN_PIN NONE
+#endif
+
+#ifndef GYRO_2_CLKIN_PIN
+#define GYRO_2_CLKIN_PIN NONE
+#endif
+
 #ifdef MPU_ADDRESS
 #define GYRO_I2C_ADDRESS MPU_ADDRESS
 #else
@@ -68,14 +76,15 @@
 #endif
 
 #if defined(USE_SPI_GYRO) && (defined(GYRO_1_SPI_INSTANCE) || defined(GYRO_2_SPI_INSTANCE))
-static void gyroResetSpiDeviceConfig(gyroDeviceConfig_t *devconf, SPI_TypeDef *instance, ioTag_t csnTag, ioTag_t extiTag, uint8_t alignment, sensorAlignment_t customAlignment)
+static void gyroResetSpiDeviceConfig(gyroDeviceConfig_t *devconf, SPI_TypeDef *instance, ioTag_t csnTag, ioTag_t extiTag, ioTag_t clkInTag, uint8_t alignment, sensorAlignment_t customAlignment)
 {
     devconf->busType = BUS_TYPE_SPI;
     devconf->spiBus = SPI_DEV_TO_CFG(spiDeviceByInstance(instance));
     devconf->csnTag = csnTag;
     devconf->extiTag = extiTag;
     devconf->alignment = alignment;
     devconf->customAlignment = customAlignment;
+    devconf->clkIn = clkInTag;
 }
 #endif
 
@@ -91,7 +100,7 @@ static void gyroResetI2cDeviceConfig(gyroDeviceConfig_t *devconf, I2CDevice i2cb
 }
 #endif
 
-PG_REGISTER_ARRAY_WITH_RESET_FN(gyroDeviceConfig_t, MAX_GYRODEV_COUNT, gyroDeviceConfig, PG_GYRO_DEVICE_CONFIG, 0);
+PG_REGISTER_ARRAY_WITH_RESET_FN(gyroDeviceConfig_t, MAX_GYRODEV_COUNT, gyroDeviceConfig, PG_GYRO_DEVICE_CONFIG, 1);
 
 void pgResetFn_gyroDeviceConfig(gyroDeviceConfig_t *devconf)
 {
@@ -106,7 +115,7 @@ void pgResetFn_gyroDeviceConfig(gyroDeviceConfig_t *devconf)
     // All multi-gyro boards use SPI based gyros.
 #ifdef USE_SPI_GYRO
 #ifdef GYRO_1_SPI_INSTANCE
-    gyroResetSpiDeviceConfig(&devconf[0], GYRO_1_SPI_INSTANCE, IO_TAG(GYRO_1_CS_PIN), IO_TAG(GYRO_1_EXTI_PIN), GYRO_1_ALIGN, customAlignment1);
+    gyroResetSpiDeviceConfig(&devconf[0], GYRO_1_SPI_INSTANCE, IO_TAG(GYRO_1_CS_PIN), IO_TAG(GYRO_1_EXTI_PIN), IO_TAG(GYRO_1_CLKIN_PIN), GYRO_1_ALIGN, customAlignment1);
 #else
     devconf[0].busType = BUS_TYPE_NONE;
 #endif
@@ -120,7 +129,8 @@ void pgResetFn_gyroDeviceConfig(gyroDeviceConfig_t *devconf)
 #endif // GYRO_2_CUSTOM_ALIGN
 
 #ifdef GYRO_2_SPI_INSTANCE
-    gyroResetSpiDeviceConfig(&devconf[1], GYRO_2_SPI_INSTANCE, IO_TAG(GYRO_2_CS_PIN), IO_TAG(GYRO_2_EXTI_PIN), GYRO_2_ALIGN, customAlignment2);
+    // TODO: CLKIN gyro 2 on separate pin is not supported yet. need to implement it
+    gyroResetSpiDeviceConfig(&devconf[1], GYRO_2_SPI_INSTANCE, IO_TAG(GYRO_2_CS_PIN), IO_TAG(GYRO_2_EXTI_PIN), IO_TAG(GYRO_2_CLKIN_PIN), GYRO_2_ALIGN, customAlignment2);
 #else
     devconf[1].busType = BUS_TYPE_NONE;
 #endif

src/main/pg/gyrodev.h

@@ -45,6 +45,7 @@ typedef struct gyroDeviceConfig_s {
     ioTag_t extiTag;
     uint8_t alignment;        // sensor_align_e
     sensorAlignment_t customAlignment;
+    ioTag_t clkIn;
 } gyroDeviceConfig_t;
 
 PG_DECLARE_ARRAY(gyroDeviceConfig_t, MAX_GYRODEV_COUNT, gyroDeviceConfig);