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Adafruit RGB Matrix with M4: what's the why?
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Adafruit RGB Matrix with M4: what's the why?

by blnkjns on Tue Jan 05, 2021 5:01 am

https://learn.adafruit.com/32x16-32x32- ... rix-shield
At the end there is a modification for use with the M4. Nice to see this explained in detail, but I miss the the WHY.
Why is the regular pin 8 not suitable?

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Re: Adafruit RGB Matrix with M4: what's the why?

by adafruit_support_mike on Tue Jan 05, 2021 1:22 pm

Some of the SAMD51's GPIO pins are weaker than the others. They belong to different 'power domains' inside the chip. Pin 8 happens to be one of those weaker pins.

The CLK signal to an LED matrix needs to be able to deliver enough AC current to toggle all the shift buffers, plus the parasitic capacitance of the cable and the PCB. The SAMD51's weaker pins can't do that reliably.

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Re: Adafruit RGB Matrix with M4: what's the why?

by blnkjns on Wed Jan 06, 2021 5:47 am

Thank you very much

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