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Topic: Need help: How to make my own 24x16 LED Matrix display (Read 7880 times) previous topic - next topic

plastygrove


Could be  you're just going too fast, got too much flashing too quick, the eye can't take it in.
Slow it down some, and clearly turn off a column before turning on the next one.


No, I've played with the delay - from 0 to 5 and it works as expected. So there's nothing wrong with that. My mistake, the multiplexing does work fine. It explains why a single row is quite bright even though a single column is not. It's because rows are generated by switching on one anode at a time while keeping the cathodes constant. But the columns are generated by several anodes at once and a single cathode turned on. Which causes the brightness to dim, possibly because of the low sink value of the 4094.
My blog Emptiness in Void. New to Microcontrollers? Learn [url=http://www.arduino.cc/playground/Cod

plastygrove

Looks like I'm gonna keep this thread alive even if it kills me!  :P

My friendly neighbourhood parts guy didn't have any of the high current TPIC6B595s. But thankfully, he finally got the 74HC595s and it has made a world of a difference over the HCF4094Bs.

One curious thing to note. Initially I had the same problem as earlier where the rows were bright and columns weren't. But when I changed the orientation by 90 degrees (in the code I mean), it suddenly looks great. All LEDs are of more or less equal brightness.

Couple of things to note. I switched from using shiftOut to SPI and wow! The speed has increased by more than 10 times. Secondly, I got some pretty 8x8 bit fonts from Richard Prinz's Pixel ROM Font Editor. It has a whole bunch of pre-built fonts from the C64, Macintosh era.
My blog Emptiness in Void. New to Microcontrollers? Learn [url=http://www.arduino.cc/playground/Cod

CrossRoads

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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