This topic was covered for the case of HAL in this thread:
https://community.st.com/s/question/0D53W00000rZAQM/default-hsi-calibration-value-wrong-in-stm32cubeide
But my case is for LL which still seems to have this issue, in the generated code.
I found this problem because the baud rate of 115200 on USART2 was so far off that serial comms was not possible. This is only a problem when RCC is set to use LL. When RCC is set to use HAL, the correct value of 64 is used for HSI calibration and I had no serial comms problem.
I believe I am on latest STM32CubeIDE software and toolchain repository for my board:
STM32CubeIDE:
Version: 1.6.1
Build: 9958_20210326_1446 (UTC)
Repository version: STM32Cube_FW_L4_V1.17.0
Another issue: It seems the Configuration Pane for RCC will not let me set this parameter (HSI Calibration Value) to the correct default value of 64. It is being limited to 31.
The generated code from main.c is below. The line in question is:
LL_RCC_HSI_SetCalibTrimming(16);
-----------------------------
void SystemClock_Config(void)
{
LL_FLASH_SetLatency(LL_FLASH_LATENCY_4);
while(LL_FLASH_GetLatency()!= LL_FLASH_LATENCY_4)
{
}
LL_PWR_SetRegulVoltageScaling(LL_PWR_REGU_VOLTAGE_SCALE1);
LL_RCC_HSI_Enable();
/* Wait till HSI is ready */
while(LL_RCC_HSI_IsReady() != 1)
{
}
LL_RCC_HSI_SetCalibTrimming(16);
LL_RCC_PLL_ConfigDomain_SYS(LL_RCC_PLLSOURCE_HSI, LL_RCC_PLLM_DIV_1, 10, LL_RCC_PLLR_DIV_2);
LL_RCC_PLL_EnableDomain_SYS();
LL_RCC_PLL_Enable();
/* Wait till PLL is ready */
while(LL_RCC_PLL_IsReady() != 1)
{
}
LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_PLL);
/* Wait till System clock is ready */
while(LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_PLL)
{
}
LL_RCC_SetAHBPrescaler(LL_RCC_SYSCLK_DIV_1);
LL_RCC_SetAPB1Prescaler(LL_RCC_APB1_DIV_1);
LL_RCC_SetAPB2Prescaler(LL_RCC_APB2_DIV_1);
LL_Init1msTick(80000000);
LL_SetSystemCoreClock(80000000);
LL_RCC_SetUSARTClockSource(LL_RCC_USART2_CLKSOURCE_PCLK1);
LL_RCC_SetUSARTClockSource(LL_RCC_USART3_CLKSOURCE_PCLK1);
}
