S32KのトピックRe: PWM triggers

PWM triggers

Ayaz — Mon, 07 Oct 2024 07:56:00 GMT

I am triggering the ADC at 20KHz using three PWM signals. All PWM signal shares a common time base, as illustrated below:

eMIOS_MCL ---> PWM ---> BCTU ---> ADC

TimeBase_CH24_A_20KHz ---> PWM_Signal_1
---> PWM_Signal_2
---> PWM_Signal_3
I would like to apply an offset so that each PWM signal triggers sequentially after the previous one has completed . While I have successfully applied the offset to the time base, I am looking to see if it is possible to apply this offset to each individual PWM signal ex (Phase Shift or Trigger Delay).

Re: PWM triggers

PetrS — Mon, 07 Oct 2024 11:58:36 GMT

Hi,

there is no delay option on BCTU module, external triggers are arbitrated based on its priority (lower number, higher priority), when they are asserted at the same time to the same ADC.
So an offset, if needed, must come from eMIOS module. The channel flag represents a trigger for BCTU. Thus this trigger placement depends on eMIOS mode used, when flag is generated.
Some modes generate flag on PWM edge, while for example OPWMT mode allows placing a trigger at desired time with respect of PWM period. So maybe you can use this mode.

BR, Petr

Re: PWM triggers

Ayaz — Mon, 07 Oct 2024 12:23:49 GMT

Setting an Offset on PWM Flag Generation for Individual PWM Signals that use the same time base :

I would like to explore the possibility of setting an offset on the PWM flag generation for each individual PWM signal that uses a common time base. Specifically, I am interested in the following

Feasibility in OPWMB Mode:

Is it possible to set an offset for each PWM signal in OPWMB mode? If so, what are the steps involved in achieving this? do you have an example project for that?

Alternative Methods:

Are there other ways to set an offset for the individual PWM flag generation?
The image below is my configuration for a single BCTU trigger. is it possible to shift flag generations by phase shift? or if I switch to OPWMT mode what is the necessary configuration for setting an offset for flag generations? do you have an example project for that?

Re: PWM triggers

PetrS — Mon, 07 Oct 2024 13:37:52 GMT

Hi,

for OPWMB mode;
It is possible to set offset for each channel individually. Just set Phase Shift parameter. This value specifies leading edge of generated signal. (Phase Shift + Duty Cycle) specifies trailing edge placement. A flag is generated either on both edges or just on training edge, based on the selected setting.

For OPWMT mode;
offset can be set as well, as it is in OPWMB mode, but flag generation is based on Trigger parameter, regardless of edges placement.

BR, Petr