SWOCTRL usage

francescovico — Mon, 13 May 2019 13:38:31 GMT

Hello , I have a problem using output compare outputs.

I would like (after a generic event) to set an output compare channel output and after that run a delayed action on this output compare channel.

The wrong code is:

...

FTM0->SWOCTRL = 0x1010; /*(1) Set "1" FTM0_CH4 using Software Output Control*/
FTM0->CONTROLS[4].CnSC = 0x18; /* (2) FTM0_CH4 clear on match*/

FTM0->CONTROLS[4].CnV= (FTM0->CNT + 100); /* (3) Match delayed of 100 clock cycle*/
FTM0->SWOCTRL = 0x0; /* (4) Remove Software Output Control*/

...

After row (1) the FTM0_CH4 goes correctly high.

In row (2) and (3) I run a delayed clear of FTM0_CH4 after 100 clock cycles.

In row (4) I remove the software output control to permit delayed clear started in row (2) and (3), but after row (4) the FTM0_CH4 channel goes low immediately whithout delay.

Thanks a lot .

Re: SWOCTRL usage

razva_tilimpea — Mon, 13 May 2019 15:41:36 GMT

Hi,

The root cause for this behavior is the synchronization of the FTM module. Please check 45.5.13.6 C(n)V and C(n+1)V register synchronization Chapter.

Basically you must configure FTM to update CnV registers immediate and to generate the software trigger.

Best regards,

Razvan

S32KのトピックSWOCTRL usage

SWOCTRL usage

Re: SWOCTRL usage