Hi John, Nice port to the 16F1823 but there are a couple of changes I would make so the 5M/10M select and 10k resets get disabled in the 26M mode. For a 26M clock the 10K output should be reset 130 instructions after the output at the start of the loop to give a 20% duty cycle output. The 50% output will be correct as it changes only at the start of the loop. The OutByte can be inverted and loaded into W after the delay, so a separate StoreTemp register isn't needed. See the attached file for the changes I would have incorporated for your application. I hope you had fun customizing the divider and can find uses for similar code in other specialized divider applications.
Good Job! Richard > I got some of the cheap Pletronics OHM40480526 26MHz OCXO parts for > experiments (couldn't resist $2 each :-). For this purpose I modified the > Richard H McCorkle/Tom Van Baak code for generating a 1 pps output from a > PIC, to work with 26 MHz input, and also target the PIC 16F1823 since > that's the part I had handy. But, being new to the PIC16F family it took > some time to get all the configuration bits correct. So in case anyone else > is in that position, here's the code I ended up with: > > http://bealecorner.org/best/measure/time/source/PIC16F1823-26MHz-1pps_asm.txt > > My M12T+ GPS board is coming on a slow boat from China, so I don't yet have > any real standard to compare this with. > > But I set up two OCXOs driving two PICs, and compared the two 1pps outputs > on a 2-ch scope, after tweaking my 10k 10-turn trim pot feeding the ADJ pin > on one part to be pretty close in frequency to the other. I see a slow > steady increase in phase lag, accumulating 167 ns in 7 minutes, so I have a > frequency difference between my two oscillators of 1.67E-7/420 = 4E-10 or > 0.4 ppm. For better measurements I guess I want a PIC-TIC or equivalent. > > -John Beale > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >
PIC16F1823-26MHz-1pps.asm
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