Using PropPad as a handheld oscilloscope.

tripp · 2010-03-26 20:01

I just wrote some code that turns PropPad into a oscilloscope.
http://forums.parallax.com/showthread.php?p=877803

http://www.youtube.com/watch?v=UPyoDwEIXpk

I think the screen update is ok at 78mS, but probably it can be faster?

For now i just send plot·data via USB.

But since the propeller can use 2pins as a AD converter i will try that, but is 2.5MHz fast enough?

Would someone want to help me with the code if i post it? to make a useful oscilloscope?

' At 80MHz the ADC/DAC sample resolutions and rates are as follows:
'
' sample·· sample··············
' bits······ rate··············
'

·············
' 5······ 2.5 MHz··············
' 6····· 1.25 MHz··············
' 7······ 625 KHz··············
' 8······ 313 KHz·

 
                         3.3V
                          &#61600;
                         &#61612;&#61613;&#61614;1nF  150k&#937; 
           adcpin &#9472;&#9472;&#9472;&#9472;&#9472;&#9523;&#9472;&#9472;&#9547;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#9472;&#61629;&#61630;&#9472;&#9472;&#9472;&#9472; Analog In            
                  100k&#937;&#61628; &#61612;&#61613;&#61614;1nF
            fbpin &#9472;&#9472;&#9472;&#9472;&#9472;&#9496;  &#61602;
                         Vss

·

MagIO2 · 2010-03-26 21:09

Do you do a full screen refresh? You should store the previous line in a buffer ... that's only 320 bytes ... you can use this info for erasing only the pixels you painted white in the previous measurement.

repeat 320
1a. erase old pixel
1b. measure
2. write new pixel and store

This way you should get much higher refresh-rates.

Using PropPad as a handheld oscilloscope.

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