AM3358: detect glitches on ECAP input.

Daven McCalla

Part Number: AM3358

I'm using ECAP input capture to determine speed from a position sensor. An ESD hit can cause glitches on the ECAP input pin. The ECAP is configured to capture on the rising edge. A simple way to detect a glitch would be to read the pin value after each capture event. If the input is still high after a capture event, then the capture is good. If the input is low after a capture event, then it was a glitch.

Is there a way to read the pin value while the pin is configured for ECAP input capture?

over 4 years ago

0 Daven McCalla over 4 years ago

Prodigy 90 points

I should also mention I'm using ECAP from PRU. Here's my ECAP settings:

CT_ECAP.ECCTL1 = 0x0102; //CAP1POL=RISING,CTRRST1=DELTA_MODE,CAPLDEN=ENABLE,PRESCALE=DIV1
CT_ECAP.ECCTL2 = 0x00D0; //CAP_MODE,CONTINUOUS,SYNCO=DISABLE,SYNCI=DISABLE,TSCTRSTOP=RUN

0 PaulM over 4 years ago in reply to Daven McCalla

TI__Mastermind 28015 points

I am working to confirm, but you may be able to read the pin state using the GPIO module (maybe even the GPI of the PRU) even although neither these are not selected by the pinmux.

I'll follow-up once I get confirmation.

Paul

0 Daven McCalla over 4 years ago in reply to PaulM

Prodigy 90 points

That would be great! Otherwise, I'll have to route the signal to a second PRU pin just to be able to read the signal after the capture event. This would mean a change to the PCB layout

+1 PaulM over 4 years ago in reply to Daven McCalla

TI__Mastermind 28015 points

Daven

I'm afraid that this feature is not supported on the AM335x family of devices. It's a new feature on newer devices such as AM64x.

--Paul

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AM3358: detect glitches on ECAP input.