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TMS320F2812 HW interrupts priority

Yannick Sereckissy
Prodigy 105 points
Other Parts Discussed in Thread: TMS320F2812

Hi,

I am writing a serial communication driver for a high speed memory dump application (921000+ b/s) using SCIA interface of the TMS320F2812 DSP. Transmission and reception are working fine. However, to avoid interrupt overhead, I implemented my ISR to do just what it needs to, which is storing the received bytes in an intermediate buffer. I want to implement a message processor using the CPU timer1 interrupt that kicks in every 20 microseconds to treat received message if any. My big surprise is that this interrupt is preempting my serial Rx interrupt all the time. The discrepancy is that my understanding of SPRU078E is that M_INT9 (sci Tx and Rx) has higher priority than M_INT13 (CPU Timer1). am I missing something?

  • 0
    Guru 192875 points

    Hi Yannick,

    Yannick Sereckissy said:
    My big surprise is that this interrupt is preempting my serial Rx interrupt all the time. The discrepancy is that my understanding of SPRU078E is that M_INT9 (sci Tx and Rx) has higher priority than M_INT13 (CPU Timer1). am I missing something?

    If you feel that you need to prioritize your interrupts, check this wiki article:

    http://processors.wiki.ti.com/index.php/Interrupt_Nesting_on_C28x

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Prodigy 105 points

    Hi Gautam,

    Thanks for this valuable wiki article. Here is what was happening:

    M_INT13 was not preempting M_INT9 as stated in my initial post. but the problem was that whenever M_INT13 ISR took the processor, it did not release for a longer time than one byte reception duration. as a consequence and because the CPU disables interrupts before executing this ISR, M_INT9 cannot execute and overrun happens causing the RXBUFF to be overridden.

    Now the problem is solved and I can properly transmit and received at various speeds up to 1.25Mb/s

    Thanks.

  • 0 in reply to Yannick Sereckissy
    Guru 192875 points

    Yannick Sereckissy said:
    Now the problem is solved and I can properly transmit and received at various speeds up to 1.25Mb/s

    That's Great, Yannick!

    Goodluck & Regards,

    Gautam