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STM32F334 24MHz+ PWM not stable

Question asked by Nair.Previn on Dec 14, 2016
Latest reply on Dec 19, 2016 by Nair.Previn

I am having trouble getting a stable PWM of greater than 24MHz on the STM32F334 discovery board. Below are the configurations I have:

 

8MHz external Oscillator

SYSCLK = 72MHz (PLLMUL * 8MHz, PLLMULL = 9)

HRTIM source = 144MHz (SYSCLK * 2)

HRTIM frequency = 4.608GHz (DLLMUL * 144MHz, DLLMUL = 32)

 

The instability appears as though the signal stays high for 1 full period, and then operates at the correct frequency, repeatedly. This happens more frequently as the frequency increases further beyond 24MHz.

The interesting thing is that 36MHz is stable, could be because it is a factor of SYSCLK. 

 

Has anyone else seen this problem?

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