sam white

Important changes to forums and questions

All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.

9 years, 12 months ago.

OSC clock

How do you set the OSC clock supply to use MCO from ST-link?...what is the default seting (r/c)? based on the manual you:

The following configuration is needed to use the MCO from st-link: – SB54, SB55 OFF – R35,R37 removed – SB16, SB50 ON

but does that set the clock for 84mhz when using the mbed compiler and how do you check that the clock speed is actually running at 84mhz? 

Question relating to:

Last updated: 20 Apr 2021
Affordable and flexible platform to ease prototyping using a STM32F401RET6 microcontroller.

1 Answer

Wim Huiskamp
9 years, 12 months ago.

In principle you can find out what the clock is by using the following code:

printf("CPU SystemCoreClock is %d Hz\r\n", SystemCoreClock);

Peter Drescher has worked on some code to switch to external crystals. However, ST are also working on updates of the mbed libs and this should be incorporated in one of the next releases of mbed libs.