topic Re: MPC5744P eTimer measurement problem in MPC5xxx

MPC5744P eTimer measurement problem

nathan_ — Tue, 04 Jul 2017 04:02:39 GMT

Hello,

I am learning how to use the eTimer module of MPC5744P to measure the duty cycle of PWM.

I have found the demos named"MPC5744P-eTimer-frequency_measurement-GHS614" which is in the attachment.

I can not understand some programs.

1. in the eTimer_Init() function, eTimer0 channel 0 and channel 1 are both configured, but in the SIUL2_Init() function, only eTimer0 channel 1 is enabled, why channel 0 is still can be used?

2. what's the meaning of cascaded mode? is it a mode of combining the results of channel 0 and channel 1?Can I do not use channel 0, just use channel 1 to measure the duty cycle?

3. Does anyone have other demos of eTimer measurement which can be shared with me ? thanks very much.

best regards

Original Attachment has been moved to: MPC5744P-eTimer-frequency_measurement-GHS614.rar

Re: MPC5744P eTimer measurement problem

PetrS — Tue, 04 Jul 2017 06:05:20 GMT

Hi,

the eTimer channel 1 input is used as secondary input source for both eTimer channels. Measured signal is connected to this input and the signal edge triggers the Capture logic on both channels.
channels are cascaded to provide 32bit counting capability, which eases wide frequency measurement without another SW intervention. There is no problem to use just 16bit counter, but you would probably need to take care of counter overflows.

BR, Petr

Re: MPC5744P eTimer measurement problem

nathan_ — Tue, 04 Jul 2017 06:58:21 GMT

thank you for you responce.

Actually, I need to use the eTimer 0 , channel 1 to channel 5 for duty cycle measurement.

Does it mean that I can not use the cascaded mode?Because I do not have more channels to provide the 32bit counting capability.