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FFTC - end of packet interrupt

Sebastian D.
Intellectual 265 points

Hi,

in the Keystone Training of the FFTC ( http://learningmedia.ti.com/public/hpmp/KeyStone/13_FFTC/index.html ) it is pointed out, that using the PDSPs(named "PKTDMA Accumulator Interrupt" in slides) accumulation firmware is the preferred method to signal the completion of the FFT operation. But there is no reason described. 

An other method is the End of Packet Interrupt(EOP). The EOP interrupt seems to be triggered before RX PacketDMA is complete ("EOP notification:The complete packet is delivered to the PKTDMA [...]"). Or does "delivered to the PKTDMA" mean, that the descriptor is already pushed to the destination queue?
The FFTC user guide does not seem to contain further information about this interrupt.

So my question is:

Is it save to use the End of packet interrupt to signal completion? Is the FFT result already in the destination queue, when I do the interrupt handling?

Thanks,

Sebastian

  • 0
    TI__Genius 12135 points

    Hi Sebastian,

        As noted in section 2.2 of the FFTC user guide, the core FFTC module supports error and debug interrupts. The EOP interrupt would be classified as a debug interrupt. The FFTC relies on the 'Multicore Navigator' for data interface. The FFTC and the Navigator are independent modules which interface with each other. Due to this the FFTC has no control (or indication) on data delivery or  delivery status to the destination which is controlled by the Navigator. So the EOP interrupt only signals that the FFTC has completed the delivery of the packet payload to the Navigator.

       This is the reason the Accumulator interrupts or using one of the 'Queue Pend' interrupts is the preferred method.

    Regards,

    Sudhanand.