CAN with internal oscillator

trevor1 · ‎2009-05-17

Posted on May 17, 2009 at 16:37

trevor1 · ‎2011-05-17

Posted on May 17, 2011 at 13:00

Hi,

Is an external crystal required to use CAN (as is the case with USB) or can I use the internal oscillator? The documentation I've read does not mention that a crystal is required.

Thanks

Trevor

tberk1 · ‎2011-05-17

Posted on May 17, 2011 at 13:00

I had wondered this as well, and found in the BOSCH CAN Bus spec found in a link from wikipedia the following:

''A maximum oscillator tolerance of 1.58% is given and therefore the use of a ceramic

resonator at a bus speed of up to 125 Kbits/s as a rule of thumb''

''For the full bus speed range of the CAN protocol, a quartz oscillator is required. ''

Therefore I would run w/ a quartz crystal.

Todd

trevor1 · ‎2011-05-17

Posted on May 17, 2011 at 13:00

Thanks Todd. I'll go with a crystal then.

amin2 · ‎2011-05-17

Posted on May 17, 2011 at 13:00

The STM32 bxCAN is connected to PCLK1 (APB1 clock ) : 36 MHz max