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ECAP problem OMAPL137

Aquiles Lacruz
Intellectual 385 points

Hello,

My name is Aquiles Lacruz and I'm currently working on a project in which I'm using an OMAPL137 EVM board, at the moment I'm trying to make an application that will run several tasks and I'm doing so using just the DSP because I want the ARM to handle interfaces later on.

The application has EDMA, ECAP, SPI and other modules working at the moment, but I'm finding some discrepancies working with the ECAP in capture mode.

Let me give you a background on my application. I have 4 HWIs so far:

  • SPI: this one lets me know when an ADC is done converting data, and acts like a trigger for an EDMA event to occur and handle the SPI communication.
  • EDMA: this one is called when a certain number of SPI reads have been accomplished and just calls for a SWI that calculates values.
  • ECAP0: this one has the ECAP working as an APWM and sends a signal to the ADC to convert the data.
  • ECAP1: this one has the ECAP on capture mode and it's required to calculate the frecuency of the data is read. This one is presenting issues, If I have all the other things running, this interruption won't be accurate. I tried just switching a GPIO on and off on this interruption and saw that it wasn't regular. Sometimes it happened and sometimes it didn't. I want to know if there is something that you could think of that would be happening. It's specially strange since this HWI should happen at a rate of ~60Hz which doesn't seem like much.

Just so you know, I'm disabling interruptions while inside ISRs. I have 1 SWI, which transforms the data from 16bits to 32 bits, and it's run every few interruptions.

 I would like to know if there is something special that I should be doing, since the data I recover from the CAP registers doesn't make much sense and it's not regular. It should be always the same as I have the circuit connected to a Signal Generator that is set at 60Hz. 

Please if you think of anything let me know as I've been trying everything I can think of. Also I'm working iwth internal DSP clock, just in case you were wondering.

Appreciate the help,

~ Aquiles Lacruz