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LP-AM243: Low Latency Interrupts

Dylan Tarter
Intellectual 320 points
Part Number: LP-AM243


I am trying to find an example of this behavior. I want to have a buffer-less interrupt to get as precise time measurement as possible on a pin. 

I have a GPS PPS pin which is ticking and it would be ideal to be able to detect the pin going high with as low clock cycles as possible to ensure it is as accurate as possible, that way minor adjustments can be made to correct timing errors on the device. Is there a maybe a pin that can do this? My current GPIO interrupt system is based on the GPIO interrupt example but I am not 100% confident it is low enough latency for this situation.

  • +1
    TI__Guru 55955 points

    Hi Dylan,

    The GPIO interrupt example is using HwiP_construct to create a HWI object and register the callback function to the GPIO interrupt. When the interrupt happens, the VIM will call the system level ISR, then in turn calls the registered callback function. There is some extra delay there for sure, but the delay is less than 100ns. If you really want the lowest possible latency, then you have to deal with the VIM directly. On the other hand, you will lost the advantage of using HwiP.

    Best regards,

    Ming

  • 0 in reply to Ming Wei
    Intellectual 320 points

    Ok, a delay of around 100ns should be tolerable in my case.