STM32H743VIT6 increasing cpu clock not working

[boostedmonkey]

I am trying to increase the cpu speed of a custom board with stm32h743VIT6 and 16mhz crystal. However, once I change the speed, the UART output prints out gibberish. I have verified the UART works with the HSI at default speed of 64Mhz. Attached is the code and board schematics. Thanks for the help. 

[AScha.3]

How you make the setup , the clock tree ?

In Cube set HSE crystal, set in clock tree to (16 M) , set the PLL to get...whatever you want, up to 400M;

then set uart to the bitrate you want, generate code...

[Andrew Neil]

once I change the speed, the UART output prints out gibberish

That almost certainly means that your baud rate is wrong.

Did you update the configuration to match the new clock speed?

Have you verified that the clock speed is actually what you think it is?

Have you used an oscilloscope or analyser to see what baud rate you are actually getting?

[boostedmonkey]

I have changed the baudrate to match the expected 120mhz / 115200 expected out with the settings i have, still no dice. Thanks for the suggestion though, I also dont have access to a oscilloscope at the moment but will have a look when i can.

[Andrew Neil]

I have changed the baudrate to match the expected 120mhz

But how have you verified that it is actually 120MHz ?

In the absence of a scope, try ​@TDK’s suggestion of blinking a LED as a frequency you can confirm with a stopwatch.

 

Your code looks like you didn’t use CubeMX?

So try doing it with CubeMX - if that works, check your calculations against it...

[TDK]

This is a clock rate issue.

Is HSE_VALUE set to 16000000?

Blink an LED at 1s and verify with a clock to verify clock in the absence of a scope.

[Andrew Neil]

 a custom board

Can you get it to work on an ST board ?