[Cryptech Tech] FMC Arbiter

[Fredrik Thulin]

On Thursday, August 27, 2015 12:17:05 AM Павел Шатов wrote:
...
> 4) 25 MHz HSE crystal on my board doesn't work, that's why I temporarily
> configured it to operate from 16 MHz HSI oscillator. Fredrik gave me a
> hint on how to fix this, but I haven't time to get to an RLC meter so far.

It's a hardware bug I'm afraid. As shown in the datasheet at 

  http://www.farnell.com/datasheets/1482310.pdf

the 25 MHz crystal wants Vdd on top left pin, and GND on bottom right pin.

With that, and 15 pF C0G caps (maybe 10 would be even better, considering the 
capacitance in the board and pins), my scope shows clean 25.00 MHz oscillation 
on top right pin of the crystal.

I'm still getting some HAL error from HAL_RCC_OscConfig() though. Will try and 
figure out what's wrong.

Apparently, my UART and LED test programs didn't run off the HSE since there 
were no working crystal there. Missing return value checks in 
SystemClock_Config() made them continue executing using HSI.

/Fredrik