Nucleo F401RE fails to execute Clock init issue

maxgerhardt · December 30, 2020, 3:06pm

Okay then that’s good, but the title and text of the first post is still wrong then.

The clock init code is at

stm32duino/Arduino_Core_STM32/blob/b626ed2142b9dac6147d44336f417ad91e091879/variants/NUCLEO_F4x1RE/variant.cpp#L109-L166


      
          #ifdef __cplusplus
          extern "C" {
          #endif
          /**
            * @brief  System Clock Configuration
            *         SYSCLK = 100000000 Hz for ARDUINO_NUCLEO_F411RE
            *         SYSCLK = 84000000 Hz for ARDUINO_NUCLEO_F401RE
            * @param  None
            * @retval None
            */
          WEAK void SystemClock_Config(void)
          {
            RCC_OscInitTypeDef RCC_OscInitStruct = {};
            RCC_ClkInitTypeDef RCC_ClkInitStruct = {};
          
            /* Configure the main internal regulator output voltage */
            __HAL_RCC_PWR_CLK_ENABLE();
          #ifdef ARDUINO_NUCLEO_F401RE
            __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);
          #else /* ARDUINO_NUCLEO_F411RE */

This file has been truncated. show original

And looks “okay”. Depending on whether it’s a ARDUINO_NUCLEO_F401RE or a ARDUINO_NUCLEO_F411RE operates the HSE in BYPASS mode, expecting an input frequency of 8 MHz to then use the PLL with factors / divisors, in the first case, of “/ 8 * 336 / 4” to get 84 MHz. For the F411RE it changes the factors to to / 4 * 100 / 2 to get 100 MHz.

But for that to work the clock needs to get through to the STM32. And that is by default not the case? SB16 is open on maybe older boards, when it should be closed so that the chip gets the clock?

Edit: On my Nucleo F103RB board, the SB16 bridge is closed / jumpered with 0 Ohms.