Asymmetric output from FTM

[t_insect80]

Hello.

For some reason, I want to make mke14f512vll16 FTM output on specs below.

- up-down count

- complementary output

- different value in up and down counting

to realize such specs, I set registers below.

-CPWMS

-COMP

-CNTMAX, CNTMIN

-set LDOK on the top of reload and overflow interrupt manually

And I write C0V to different value on reload and overflow interrupt, however, the output looks symmetric.

is it impossible to realize asymmetric output on complementary CPWMS mode?

if you know some idea, i’m glad to hear it.

Best regards.

[Sabina_Bruce]

Hello,

I'd recommend taking a look at the following application note, Features of the FTM Module. This document describes the configuration necessary to have an asymmetric signal. Here it covers what it supports and doesn't support. 

You can also verify your configuration on section 41.5.9 of the Reference Manual. Also consider that to have an asymmetric pwm signal, in Combine mode, the PWM first edge (channel (n) match: FTM counter = C(n)V) is independent of the PWM second edge (channel (n+1) match: FTM counter = C(n+1)V), as stated in the reference manual.

Let me know if you have any further questions from the above documents.

Best Regards,

Sabina