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F28M36P63C2: IO lines operating not as we expect

ajayt
Genius 9555 points
Part Number: F28M36P63C2
Other Parts Discussed in Thread: DRV8312, DRV8303

We’re using TI Concerto Microcontroller F28M36P63C2ZWTS22 to drive DRV8303 and DRV8312. The product has been launched last year and we have some failure issues

 

It has been reported from the field that there are some intermittent problems during the device use. We looked into the problems and found that there are some I/O pins read unexpected low when polling these pins. But we didn’t observe any signal change when using oscilloscope to monitor these I/Os. When we change the polling frequency, we can confirm that the low state only lasts less than 1 us (minimum delay we can set in Firmware). When we change one of these lines to an interrupt, we observed many interrupts occurred within just 1 ms. We tried to read the I/O state inside the interrupt function. But the pin quickly recovers to high when its state is checked.

We thought this might be some noise which should be able to be filtered when we increase the qualification time on these I/O readings. But the results show nothing changed even after we increased the qualification time from 7ns to 6us.

My questions to TI are:

1.     What could possibly be the reason that we read low on these pins but not observed it on an oscilloscope?

2.     Why did the qualification time change not able to filter out these short duration of glitches?

3.     What is the typical time of an interrupt response by default (no qualification sampling change)?

 

I

 

  • 0
    TI__Mastermind 41415 points

    Ajayt,

    A few questions

    1. Is this only happening on one device, or is it happening on multiple devices?
    2. Can you confirm that the GPIO is configured as an input and that this configuration is not changing?
    3. Similarly can you confirm that the pin's pull-up configuration is not changing?
    4. What core are the pins assigned to?
    5. Do you know if the pin is toggling high or toggling low?
      1. if you force the pin high does the behavior happen?
      2. if your force the pin low does the behavior happen?

    To answer your questions

    1. I'm not quite sure, my first thought is to ensure that your oscilloscope is setup correctly and can detect small glitches. But provided it is setup correctly, perhaps something internal to the device is causing this.
    2. This is weird. This points to that it might be something the qualification cannot filter.
    3. This depends on the source of the interrupt, but 13 cycles for an unqualified XINT1 interrupt.

    Regards,
    Cody