How to measure the core operating frequency

[hariprasad]

Posted on February 09, 2015 at 12:20

I am using the STM32F429 Discovery board. I followed the

http://stm32f4-discovery.com/2014/04/library-03-stm32f429-discovery-system-clock-and-pretty-precise-delay-library/

to run the core at specified frequency. So once I have configured the all the PLL reg vals, How can I check whether the core is running at desired frequency ? (Is it possible to see via some output pin) #clock #stm32f429

[Tesla DeLorean]

Posted on February 09, 2015 at 13:05

Well there are the MCO pins, MCO1 (PA8) is capable of outputting a number of internal clocks. The pins are limited to 100 MHz, so you need to select a divider (1-5) for the pin output. You could check speed via any TIM output pin, and the predictable nature of the gearing inside.

The code to set the baud rate reviews the clock and PLL setting so come up with a number for the gearing there, you just have to provide an accurate HSE_VALUE. You could bench the clocks via LSI/LSE.