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High frequency clock signal generation

Question asked by Félix TREFOU on Apr 16, 2018
Latest reply on May 3, 2018 by Nawres GHARBI

Hi,

I'm facing a problem i can't solve. It seem so simple but i think i need an other point of view.

For a project using a led driver (LED1642GW) i need a clock in 20MHz~30MHz.

I forgot this oscillator in my hardware so i want to generate it with my MCU (and it will be cheaper).

 

I made the most simple project for my stm32L476VGT:

- HSI (or MSI) speeded up to 80MHz through PLLCLK.

- TIM5 with PWM or CC on Channel 1

- PA0 on Alternate function (TIM5 ch5) with very high speed

 

Reference manual is saying that internal clock of the timer is APB (so 80MHz).

Despite of my differents trys, i don't managed to get an output signal at 20MHz.

With the example bellow i expected a signal at 80/80 = 1MHz but i only get 400kHz...

 

Here is some screens:

 

Did i miss something? Or does the GPIO not made for this purpose?

 

Thanks!

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