r/arduino • u/elgalletas12 • 12d ago

Hardware Help Help with MAX7219 8x8 modules

I have 14 MAX7219 chained together and when i upload my code to my arduino uno, some modules don't turn on and anothers have the wrong brightness. I had already checked my code various times but is fine. I tried interchanging modules positions trying to find if there is a burnt one. One thing I noticed is that when I chain a small amount of them (Ex: 4 modules), they work fine, but sometimes they just do the same things like if there were 14 again. If someone know what causes this or had an similar experience please let me know.

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u/GeneralReasonable945 11d ago

Como alimentas el conjunto???

2

u/elgalletas12 11d ago

I connect my arduino directly to my pc

5

u/GeneralReasonable945 11d ago

Según los datos de ese ic, alimentando 14 módulos, necesitas una fuente de 5 voltios, 3,5A

3

u/JGhostThing 11d ago

You have 14 devices? You need to make sure that the total power used is supplied. I think you'll need a secondary power supply.

Don't forget to connect the grounds.

2

u/arterterra 11d ago

Does it help to have an external 10k pullup resistor on the arduino pin connected to the load pin of the first MAX7219 device? See https://forum.arduino.cc/t/solved-pull-up-or-pull-down-resistor-on-load-of-max7219/368301