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Author Topic: LED Matrix troubleshooting  (Read 819 times)
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Hi everyone.
I'm trying to get a LED matrix to work with:
- a MAX7219 IC
- an Arduino
- this lib: http://www.arduino.cc/playground/Main/MAX72XXHardware

The problem is that my LED matrix refuses to display anything but "all the leds on". I've triple-checked the wiring, tested everything, and in last resort I this my matrix could be a common cathode one...
Do you know how I can test wether it's a common anode or cathode?
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Do you know how I can test wether it's a common anode or cathode?

Tried looking at the datasheet?  We need to know the details such as part number and how you've wired it up to help further.
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The datasheet for teh MAX72xx indicates that it is for common cathode.
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Well wait a minute here. Before we go looking at the wiring, for the fact that all the lights turn on (if you wired the lights backwards, they would not come on. Though I do not know if there is an adverse effect if you have only one or a few leds backwards), post your code so we can see if maybe there is a small logic issue somewhere.

If I were you though, as far as wiring, I would wire up only a couple of lights first to ensure you do have the leds wired correctly (I had one or two backwards in a 3x3 led array and man it caused a p.i.t.a. for me, but instead of ALL the lights coming on, multiple lights would come on when I was only addressing one led at a time)
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