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Topic: MAX7219 performance (Read 542 times) previous topic - next topic

Paul__B


RobFarley

#16
May 22, 2019, 03:19 pm Last Edit: May 22, 2019, 03:21 pm by RobFarley
If I'm doing something wrong tell me! I'm new to this and keen to learn from the more experienced members of this forum. I've simply wired stuff up as per the instructions I've got!

I'm fine with software, but very new to the hardware side of things.
Cheers, Rob

marco_c

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I didn't know there was a difference in which pins you use, which pins are the best to use, and the only thing I changed were the consts at the beginning of the Panel_Test to assign the pins.
There is a hardware SPI interface that works really fast. This is on set pins, which depend on the type of Arduino you are using (normally marked MISO, MISO and SS pins). You can also do SPI by bit bashing any pins you like, but this will run slower. The MD_MAX72xx library allows you to use either type. If you use the constructor with no pins, then it will default to the hardware interface for your hardware, using the SPI library. If you specify the pins, then it will bit bash directly.

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I don't know how much of a big ask this is, I'm happy to write it myself if I understood the communication to the 7219s, but that's currently a bit beyond my knowledge right now.
Not really that hard at all. You should be able to work it out from the two libraries you have. It will simplify things if you use the SPI library for the actual transmissions (with the default pins). There is lots out there describing how the SPI interface works and you can certainly use any of the generic code in MD_MAX72xx. The MAX72xx data sheet describes the command register codes you should use and how the supporting data byte is structured. Again, both libraries already do this, so I expect that if you read the data sheet and understand what SHOULD be done for comms, what the libraries ACTUALLY DO will become easier to understand.
Arduino Libraries https://github.com/MajicDesigns?tab=Repositories
Parola for Arduino https://github.com/MajicDesigns/Parola
Arduino++ blog https://arduinoplusplus.wordpress.com

RobFarley

Cool, I've have a look into it
Cheers, Rob

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