Picomite/PicoMiteVGA V5.07.05 release candidates

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Pluto Guru Joined: 09/06/2017 Location: Finland Posts: 328 |
I did also some time ago measure the max measurable frequency and came to the same conclusion as Phil99: up to 1MHz. (Using the "standard" frequency measurement. I then tested the PIO-routine that Volhout posted and with his routime the PicoMite was able to measure up to 5.4MHz. https://www.thebackshed.com/forum/ViewTopic.php?FID=16&TID=15163#191650 I used 378MHz CPU-speed (and also 378MHz speed for the PIO routine). I am not sure if 5.4MHz is the highest frequency. I used the MicroMite based signal generator made by Geoff so I am not sure if the output amplitude is sufficient as a valid input at the higher frequencies. If someone has a more proven generator for higher frequencies (>5MHz), it would be nice to see if you are getting the same or better results. 'GP0measure frequency/period using PIO 'Volhout's PIO-routine 'pio program measure pause and pulse time from GP0 in us and push both to FIFO '0 E020 'set X=0 '1 A029 'X -> fffffff '2 00C4 'jmp (pin=1) to loop2 '3 0042 'count loop1 '4 0045 'count loop2 '5 00C4 'jmp (pin=1) in loop2 '6 A0C9 'mov -X to ISR '7 8000 'push noblock '8 0000 'jmp 0 (rest is filled with 0 = jmp->0) Dim a%(7)=(&h004200C4A029E020,&h8000A0C900C40045,0,0,0,0,0,0) 'f=63e6 '2MHz gives 1us per count resolution f=378e6 'I increased this to the same as the PicoMite cpu frequency. 'configure pio1 e0=Pio(execctrl 0,0,&h1f) 'use gp0 for PIN p=0 'no GPxx pins for PIO 'program pio1 and start PIO program 1,a%() PIO init machine 1,0,f,p,e0,,0 'start pio 1,0 from adress 0 PIO start 1,0 'C1=1e-9 '1nF 'F1=175100 'measure time and convert to frequency Dim cnt%(4) DO for J=1 to 1 avg=0 avg1=0 PIO start 1,0 n=100000 'Will meare so many times and calculate the average For i=1 to n*j PIO read 1,0,5,cnt%() 'read fifo pio 1 seq 0 period1% = cnt%(4)+3 freq=f/(2*period1%) 'calc freq avg=avg+freq avg1=avg1+cnt%(4) next i PIO stop 1,0 Counts=avg1/(n*j) F1=avg/(n*j) ny=F1 print"Frequency:";F1;" counts=";counts;" nbr=";n*j; " Diff %=";abs((ny-old)/ny)*100 old=ny Next j 'pause 1000 LOOP |
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