sebastien videau

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10 years, 2 months ago.

External Clock frequency

Hello all,

I currently try to decrease the clock frequency of my Nucleo F030R8. I manage to change the internal frequency (HSI) by changing the "system_stm32f0xx.c" and it works fine but in order to reduce the power consumption i need to use an external clock source of 4 MHz, so i change it into the system file. My main program is some interuption on GPIO that I can see on oscilloscope, 8MHZ or 24 or 48 have the same result and i can see some UART message on my terminal.

Result of 4MHZ : I saw interuption are longueur than before and UART message are tottaly incorrect /media/uploads/Alamalione/uart.png I saw on "stm32f0xx_hal_uart.c" that UART could be associate with some different clock source but HSE is not one of them. /media/uploads/Alamalione/clock_source.png What should i do to make my UART communication works fine with my External clock ? Thanks and best regards.

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Last updated: 30 Mar 2019
Affordable and flexible platform to ease prototyping using a STM32F030R8T6 microcontroller.

I suspect that if you clocks are correct, the implementation might not handle your clock settings correctly ?

posted by Martin Kojtal 17 Oct 2014

Ok, I found the correction to do in "system_stm32f0xx.c". I just need to change PLL Multiplication and it's done but there is one big issue, if i try to integrate my program with the "mbed-src" it's to big and i'm out of memory ("no space in execution regions with .any selector matching") I just need to modify one line of the "system_stm32f0xx.c" but it seems i can only modify the simple "mbed" library which is constitute by .h and .o. How can I handle it ? Thanks you for your help, i'm completly stuck now..

posted by sebastien videau 17 Oct 2014
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