feat(xiao): expose onboard IMU control pins

Author: cumin777

variants/STM32C5xx/C593C(E-G)(T-U)_C5A3CG(T-U)/variant_XIAO_STM32C5.cpp

@@ -23,7 +23,11 @@ const PinName digitalPin[] = {
   PB_5,  // D13 / FDCAN2_RX
   PB_13, // D14 / FDCAN2_TX
   PB_14, // D15 / CAN_STB
-  PB_12  // Board LED, active low
+  PB_12, // Board LED, active low
+  PB_3,  // Onboard IMU / I2C2_SCL
+  PB_4,  // Onboard IMU / I2C2_SDA
+  PC_13, // Onboard IMU / INT1
+  PA_8   // Onboard IMU heater / TIM1_CH1
 };
 
 const pin_size_t analogInputPin[] = {

variants/STM32C5xx/C593C(E-G)(T-U)_C5A3CG(T-U)/variant_XIAO_STM32C5.h

@@ -22,14 +22,18 @@
 #define PB13                    14
 #define PB14                    15
 
-/* Board-only pin: it follows the XIAO connector pins in digitalPin[]. */
+/* Board-only pins: they follow the XIAO connector pins in digitalPin[]. */
 #define PB12                    16
+#define PIN_IMU_SCL             17  // PB3 / I2C2_SCL
+#define PIN_IMU_SDA             18  // PB4 / I2C2_SDA
+#define PIN_IMU_INT1            19  // PC13 / LSM6DS3TR-C INT1
+#define PIN_IMU_HEATER          20  // PA8 / TIM1_CH1
 
 /* Alternate functions used by the default board peripherals. */
 #define PA9_ALT1                (PA9 | ALT1)
 #define PA10_ALT1               (PA10 | ALT1)
 
-#define NUM_DIGITAL_PINS        17
+#define NUM_DIGITAL_PINS        21
 #define NUM_ANALOG_INPUTS       4
 
 #ifndef LED_BUILTIN