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Thread: ShiftMatrixPWM updated for Teensy3 - Almost!

  1. #1
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    ShiftMatrixPWM updated for Teensy3 - Almost!

    I have successfully converted the ShiftMatrixPWM library to work with the Teensy 3. This library uses SPI4Teensy3 and IntervalTimer libraries to maximize the speed. It handles a 10x16 RGB matrix and I will test it on a larger matrix soon. My test bed uses 2-75HC595/PNP transistor array on the anodes and 4 or 2 TLC5916/26 on the cathodes. I have a 3 to 5.5v 74HCT245 logic level converter on the output data lines of the Teensy. For the Teensy I separated the 3 & 5 volt lines, added the 2 diodes, and use a 40 amp 5 volt power supply. I have 1uf/0.1uf ceramic capacitors on each shift register - both anode and cathode.

    However, some of the LEDs stay partially lit at all times, and others partially light up as ghosts to fully lit LEDs. I have switched out the shift registers, and shortened the wiring with no luck. Also tested using a Teensy 3.0 and a 3.1. On the UNO a few LEDs stay on constantly, but is much worse on the Teensy 3 with the ghosting problem added. I've included the schematic and an image of the LED matrix problem.

    Any suggestions?
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  2. #2
    Senior Member PaulStoffregen's Avatar
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    Is the modified code posted anywhere, like github?

    Years ago (before Teensy 3.0 existed), I built a test board for ShiftMatrixPWM. I still have it somewhere. After Maker Faire, I could dig up that LED matrix and give it a try...

  3. #3
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    Thanks for the quick reply. I posted the library in github.com/Paul47/ShiftMatrixPWM2 The documentation still needs some work.

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