topic Generate PWM with 20Hz with K27 in Kinetis Microcontrollers

Generate PWM with 20Hz with K27

christophosterl — Wed, 28 Nov 2018 08:25:33 GMT

Hi,

i'm struggeling to generate a pwm with 20Hz and a duty cycle of 50%. Running the clock with 120Mhz, i get a bus clock speed of 60Mhz. Even with the maximum prescaler of 128 I'm far away from 20Hz (cause the compare value would be > 16bit).

When I'm to use the fixed frequeny clock (MCGFFCLK) by setting C1[IREFS] to 1 and set the Clock Source Selection [CLKS] to 2, I do not get any output (when triggering the pin with a scope).

Do you have any hints for me what I've forgotten or could you tell me a different/better way to solve this?

Thanks and best regards!

Re: Generate PWM with 20Hz with K27

Robin_Shen — Thu, 29 Nov 2018 06:23:08 GMT

Hi christophosterloh,

I try to import the ftm_simple_pwm example of MCUXpresso SDK_2.4.1_MK27FN2M0Axxx15.
After modify the configurations using the Peripherals Tool in MCUXpresso IDE, I can get 20Hz PWM at FTM3_CH1 pin on FRDM-K28F board.

Best Regards,

Robin

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