Forum: GNU Radio Re: problem with start/end of burst inband FPGA code

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Hugh Brunk (Guest)
on 2007-08-02 10:44
(Received via mailing list)

> > We'd greatly appreciate any help, thanks!

I noticed that you're asserting 'skip' in the WAIT state for a starting
packet, and in the HEADER state for later packets.  Without more code, I
can't tell if this makes any difference.  You might try rewriting it to
have the same state transitions and assertion of 'skip' for all packets
of a burst.


something like this:

modify the second half of HEADER state like:

    if (fifodata[`STARTOFBURST] == 1)
        // new burst; use clk to decide whether to skip
        trash <= 0;
    payload_len <= fifodata[`PAYLOAD] ;
    read_len <= 0;
    reader_state <= TIMESTAMP;
    rdreq <= 1;

and then change the WAIT state as:

        if (tx_strobe == 1)
            tx_empty <= 1 ;

        if (trash == 1) //skip second and later packets flagged as trash
           reader_state <= IDLE;
           skip <= 1;
        else if ((timestamp < (adc_time + `JITTER)
                                && (timestamp > adc_time))
                                || timestamp == 32'hFFFFFFFF)
            reader_state <= WAITSTROBE;
        // Wait a little bit more
        else if (timestamp > adc_time + `JITTER)
            reader_state <= WAIT;
        // Outdated
        else if (timestamp < adc_time)
            //skip start of burst, flag later as trash
           trash <= 1;
           reader_state <= IDLE;
           skip <= 1;
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