2024-11-04 11:23 AM
When I try setting up to use an external 10MHz reference clock on the HSE with a divisor of 1 and a multiplier of 25 it insist the frequency will be 255MHz but shouldn't it be 250MHz, Similarly for every multiplier I have tried the frequency is 5MHz off.
See attached screen shot from CubeMX.
Thanks
Chris.
Solved! Go to Solution.
2024-11-04 11:53 AM - edited 2024-11-04 01:42 PM
>it insist the frequency will be 255MHz but shouldn't it be 250MHz
Maybe - its right ? Because you set the fractional divider ....set it to zero, then try again.
btw
You set 4096 , so it gives F= Fref x (divn + 0,5 ); with Fref 10MHz, you get 5 MHz "added" .
2024-11-04 11:53 AM - edited 2024-11-04 01:42 PM
>it insist the frequency will be 255MHz but shouldn't it be 250MHz
Maybe - its right ? Because you set the fractional divider ....set it to zero, then try again.
btw
You set 4096 , so it gives F= Fref x (divn + 0,5 ); with Fref 10MHz, you get 5 MHz "added" .
2024-11-04 12:05 PM
Doesn't it have a 25 MHz crystal?
2024-11-05 09:52 AM
That was it thanks. Didn't realize that was a parameter I could change. I started it with 0 and some point I guess it had changed it.
2024-11-05 09:53 AM
Changed it to external 10MHz reference.