Bob Ammerman wrote:
>
> Ah, now it makes more sense.
>
> A couple of questions:
>
> Each wire can generate from 0 to 65535 pulses, right? (or is it 1 to
> 65535?).
>
        right
> Do the pulses have to be absolutely consistent in length?
>
        no
> Do the pulses have to be absolutely consistent in spacing?
>
        no
> How do you know how many pulses each wire needs to generate?
>
        pulses are the result of calculations (averages on 10 sec) to be
acquired
        from remote counters of another instrument.

> You say triggers come in every 10 seconds. This implies that the pulse rate
> must be at least 65535 per 10 seconds or 6554 per second, right?
>
        right

> If this is the case you have at most 152 instructions per pulse. This would
> seem to be doable.
>
> Here is some pseudocode to get you started:
>
        tanks a lot, Maurizio

> unsigned int counts[5];       // The 16-bit count value for each output
> unsigned int pulsenum;      // Which pulse we are generating
> unsigned char  active;        // Which outputs are are generating pulses for
>
> when trigger comes:
>
>     active = B'11111'           // Start with all pulses enabled
>     pulsenum = 0                  // Which pulse we are working on
>
>     do {
>           if (counts[0]  == pulsenum)
>                 active &= ~1;       // Turn off output 1
>           if (counts[1]  == pulsenum)
>                 active &= ~2;       // Turn off output 2
>           if (counts[2]  == pulsenum)
>                 active &= ~4;       // Turn off output 3
>           if (counts[3]  == pulsenum)
>                 active &= ~8;       // Turn off output 4
>           if (counts[4]  == pulsenum)
>                 active &= ~10;       // Turn off output 5
>
>           PORTB = active;         // Start pulses on all active pins
>           delay a bit
>           PORTB = 0;                 // End the pulses
>
>         ++pulsenum;
>
>     } while (pulsenum != 0);
>
> You will need to use isochronous code to get evenly spaced pulses.
>
> Bob Ammerman
> RAm Systems
> (contract development of high performance, high function, low-level
> software)
>
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--
Maurizio Viterbini
Istituto di Fisica dell'Atmosfera
Via Fosso del Cavaliere 100
00133 Roma
Italy

tel. +39 06 49934200
fax +39 06 20660291
email viterbin@ifa.rm.cnr.it

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