UART with 8MHz internal oscillator?

stankovic · ‎2008-03-08

Posted on March 08, 2008 at 15:55

stankovic · ‎2011-05-17

Posted on May 17, 2011 at 12:26

Hi,

I am working on new board that has restriction in dimension (something new? :o) and think about using only internal oscillator(8MHz).

OK, may be 32kHz for RTC if I can make it without external RTC chip (there is one ST software example about this, still need to read and test it).

My question is - is it possible to make USART working (max. baud rate 57600) with internal oscillator?

By STM32F103 datasheet max. oscillator error is +-3% (for -40,+105C), which is close to max. baud rate error allowed for UART.

As I expect that device will be all the time in range -20, +80C oscillator error is probably lower.

Also, anyone worked with CAN - what is tolerance there?

This is not so critical as I am considering SPI as alternative, distance is quite short - max 20 cm.

Thanks.

obtronix · ‎2011-05-17

Posted on May 17, 2011 at 12:26

my opinion is I wouldn't make a commercial device using the STM32 internal osc to drive a UART without some type of calibration scheme, just my opinion!