A5 core dont't run with set core clock speed

[x_dex]

Hello, I tried to run the A5 core of a TWR-VF65GS10 tower evaluation board with 480MHz. I set the A5 core clock to 480MHz and if output on observation clock pin CK01 the core clock of 480MHz could be verified. But if I run a program which toggles a pin in an while loop it runs much slower(pin toggles with 3.3MHz). I used the Processor Expert Software tool for init code generation and setting core clock to 480MHz, is there something else I have to set to make the A5 core run with 480MHz?

[kef2 · Accepted solution]

Frequency of pin toggle loop doesn't proove anything, especially on high speed MCUs. Bus clock on these is much slower than CPU clock. CKO pin is good way to check CPU frequency. If you don't believe it, then perhaps try using ARM performace monitor. It contains counter which operates at CPU clock frequency. Let it run for few seconds, then read 32bit counter and see if it makes sense. See two routines attached.