Is there a method to query the System core speed?
I’ve got a 12MHz external clock that I’m converting to 100MHz via the PLL and would like to know EXACTLY how close to 100MHZ it’s actually running. I need that number to ensure my UART, SPI, etc are accurate.
Now I can measure the Trace Clockout signal, but that'll be for a single MCU and I want to know this value for every unit we build.
You have two options here:
1) Bring out the 100MHz signal to a test point, and measure that frequency with more accurate test equipment as part of your manufacturing procedure. Then, have the test fixture write a "trim" value to your unit's NV configuration so it can adjust the clock.
2) Put a more accurate crystal or clock source on the board. Use it to run a counter and count the number of 100MHz clock edges and adjust that way. Not that at thits point you could also just run your system off the more accurate crystal or clock.