Changing BAUD-rate in AN12218SW bootloader, non-zero reset values.

roy_vanlierop — Mon, 17 May 2021 11:14:21 GMT

The AN12218SW uses the following code to change the baudrate:

/* Calculate baud settings u32Baud = 19200*/ pUART->BAUD |= LPUART_BAUD_OSR(15); u16Sbr = (u32SysClk/u32Baud)/16; pUART->BAUD |= LPUART_BAUD_SBR(u16Sbr);

This works for the default bootloader values as the calculated OSR/SBR value overlaps with the non-zero reset value. It is however not universal (at all!).

It would have been better if the AN12218SW would have used:

/* Calculate baud settings*/ pUART->BAUD = (pUART->BAUD & ~LPUART_BAUD_OSR_MASK) | LPUART_BAUD_OSR(15); u16Sbr = (u32SysClk/u32Baud)/16; pUART->BAUD = (pUART->BAUD & ~LPUART_BAUD_SBR_MASK) | LPUART_BAUD_SBR(u16Sbr);

It took me way to long to figure out the registers were non-zero. Especially OSR is very very wrong as it will always be 15 with the supplied code.

Re: Changing BAUD-rate in AN12218SW bootloader, non-zero reset values.

lukaszadrapa — Mon, 17 May 2021 14:47:48 GMT

Thanks for sharing this, I will report it as well.

Thanks,

Lukas

topic Re: Changing BAUD-rate in AN12218SW bootloader, non-zero reset values. in S32 Design Studio

Changing BAUD-rate in AN12218SW bootloader, non-zero reset values.

Re: Changing BAUD-rate in AN12218SW bootloader, non-zero reset values.