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Topic: Small 8x8 matrix driver? (Read 6 times) previous topic - next topic

fungus


I'd probably need SPI, though how slow is slow if I wanted to go the serial port route? Also the main atmega, would run at 8MHZ so it wont be super speedy anyways...


It's not really about "fast" or "slow", it's whether it's fast enough for your needs.

First you have to figure out how much data you need to send...

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Nadav Ami

Well I figure since its an 8x8 matrix, I would need to transmit 64bit strings of data at a time (maybe a few extra bits to signal a new frame is coming in or things like that)

CrossRoads

30 frames/second * 64 bytes/frame * 11 bits/byte = 21,129 bits per second.
Go to 90 frames/second (for "overhead") = 63K bits/second
Serial will not be a problem. Use 115,200 if you are concerned.
2 MBit/second SPI is not needed.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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Nadav Ami

Sweet! That actually makes perfect sense. Now as to how I would do that, would I just do a Serial.write on one end and a Serial.read on the other? and when setting it up I would set Serial.begin to 115200?

fungus

#24
Oct 12, 2012, 10:15 pm Last Edit: Oct 12, 2012, 10:24 pm by fungus Reason: 1
Ok, The McGyver in me just had to know if you can really sand down a chip to that sort of thickness.

So I grabbed a dead MZX7219 and some sand paper, and... yes you can!

I easily got it under 2mm thick (actually 1.85mm) without exposing any silicon. With a 0.8mm PCB that meets your "under 3mm" goal.





It's probably not a good way to do it if you want to make a lot of them, but it can be done. :-)

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

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