STM32F411E Disco Board - PWM

[HL1]

I have been trying to get a PWM output from PE9 by following some example online. However no PWM output at PE9 pin. The desires PWM frequency is 20kHz and duty cycle is 50%. Any suggestion what is the problem ?. Thanks.

[KnarfB]

The period is 50 and TIM1->CCR1 = 50; This won't work. For 50% PWM set period to 50-1 and TIM1->CCR1 = 25;

hth

KnarfB

[HL1]

Yes .. you are right. I overlooked this value.

[Andrew Neil]

Are you sure that PE9 is not used by anything else on the Disco board?

Check the User Manual and Schematics.

Can you toggle it using just a simple GPIO write?

[HL1]

I had checked the schematic, PE9 is free and it is not used for other things. As mentioned by KnarfB, i had set the pulse width to 100%. Hence i only see a straight line instead of a PWM signal. I did though to toggle using simple GPIO write but i need to vary the pulse width.