Properly handle HSI if selected (betaflight#14259)

* Properly handle HSI if selected In some places, PERSISTENT_OBJECT_HSE_VALUE being zero is used to imply that the MCU should be clocked from HSI, but the code doesn't really follow through and results in an invalid clock tree setup. The proposed changes should fix this. * Apply suggestions from code review Co-authored-by: Mark Haslinghuis <[email protected]> * Update system_stm32g4xx.c HSI should now be implicitly selected when SYSTEM_HSE_MHZ is defined as 0 or omitted in the target config. USE_CLOCK_SOURCE_HSI is not necessary. * Update src/platform/STM32/startup/system_stm32g4xx.c Co-authored-by: Petr Ledvina <[email protected]> * Update src/platform/STM32/startup/system_stm32g4xx.c Co-authored-by: Mark Haslinghuis <[email protected]> --------- Co-authored-by: Mark Haslinghuis <[email protected]> Co-authored-by: Petr Ledvina <[email protected]>
haslinghuis · Feb 27, 2025 · d8cd6b7 · d8cd6b7
1 parent a801aad
commit d8cd6b7
Showing 1 changed file with 6 additions and 5 deletions.
diff --git a/src/platform/STM32/startup/system_stm32g4xx.c b/src/platform/STM32/startup/system_stm32g4xx.c
@@ -118,7 +118,6 @@ void SystemInit(void)
 void SystemCoreClockUpdate(void)
 {
   uint32_t hse_value = persistentObjectRead(PERSISTENT_OBJECT_HSE_VALUE);
-
   uint32_t tmp, pllvco, pllr, pllsource, pllm;
 
   /* Get SYSCLK source -------------------------------------------------------*/
@@ -381,10 +380,12 @@ void SystemClock_Config(void)
 
   // Initializes the CPU, AHB and APB busses clocks
 
-  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_HSI48
-                              |RCC_OSCILLATORTYPE_LSI|RCC_OSCILLATORTYPE_HSE;
-
-  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
+  const bool useHse = persistentObjectRead(PERSISTENT_OBJECT_HSE_VALUE) != 0;
+  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI | RCC_OSCILLATORTYPE_HSI48 
+      | RCC_OSCILLATORTYPE_LSI 
+      | (useHse ? RCC_OSCILLATORTYPE_HSE : 0);
+  RCC_OscInitStruct.HSEState = useHse ? RCC_HSE_ON : RCC_HSE_OFF;
+
   RCC_OscInitStruct.HSIState = RCC_HSI_ON;
   RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
   RCC_OscInitStruct.LSIState = RCC_LSI_ON;