HSI clock and baudrate ?

[antonius]

Dear Members,

I changed my clock from MSI to HSI but my SPI and UART baudrate becoming wrong,

What do I miss here ?

thanks

[S.Ma]

Only you can answer a question with so little details, except Sherlock maybe?

[antonius]

Is the answer here ?

https://www.st.com/content/ccc/resource/technical/document/application_note/group0/66/fa/62/a2/5c/75/48/a8/DM00327191/files/DM00327191.pdf/jcr:content/translations/en.DM00327191.pdf

[antonius]

Not good for me, it's not supported for STM32LX series :(

[Tesla DeLorean]

If you change clocks on ​the fly, you'll have to change dividers dependent on them also.

[antonius]

yes what value for divider ?

the setting for UART3

:

void MX_USART3_UART_Init(void)

{

 huart3.Instance = USART3;

 huart3.Init.BaudRate = 115200;

 huart3.Init.WordLength = UART_WORDLENGTH_8B;

 huart3.Init.StopBits = UART_STOPBITS_1;

 huart3.Init.Parity = UART_PARITY_NONE;

 huart3.Init.Mode = UART_MODE_TX_RX;

 huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;

 huart3.Init.OverSampling = UART_OVERSAMPLING_16;

 if (HAL_UART_Init(&huart3) != HAL_OK)

 {

   Error_Handler();

 }

}

[antonius]

clock

[S.Ma]

What do you want to do? Use HSI through PLL and generate the same SYSCLK 2.097 MHz default MSI frequency?

[antonius]

I want to use 16MHz HSI, but SPI2 and UART3 are misconfigured , working on 2.097MHz but not on HSI 16MHz, by the time I have 16MHz

any clues or same experiences ? thanks

[antonius]

I put on 32MHz, only USART3 can not work properly

I make :

   USART3->BRR = 32000000/115200;

Correct me ?

///

void MX_USART3_UART_Init(void)

{

 // Configure BRR by deviding the bus clock with the baud rate

 huart3.Instance = USART3;

 huart3.Init.BaudRate = 115200;

 huart3.Init.WordLength = UART_WORDLENGTH_8B;

 huart3.Init.StopBits = UART_STOPBITS_1;

 huart3.Init.Parity = UART_PARITY_NONE;

 huart3.Init.Mode = UART_MODE_TX_RX;

 huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;

 huart3.Init.OverSampling = UART_OVERSAMPLING_16;

   USART3->BRR = 32000000/115200;

 if (HAL_UART_Init(&huart3) != HAL_OK)

 {

   Error_Handler();

 }

}