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Author Topic: Programming with MAXIM 7221CMG.  (Read 352 times)
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I came across a guy looking for information on how to build something similar to something you'd see in a Daft Punk video, so anyway after a few video searching
i come across this!

wow!


Set it to 1028p high def (don't bother trying to play it if you can't) but simply pause it.

https://www.youtube.com/watch?v=DxjmQfeYztA&feature=player_detailpage#t=117s
[video]https://www.youtube.com/watch?v=DxjmQfeYztA&feature=player_detailpage#t=117s[/video]

First of all, wow, love these daft punk helmets, but....  after telling him to go watch this video he comes back saying "but i don't know how he does it"

I think it's quite clearly painfully obvious from all the photos in high def!

So, the Maxim 7221CMG, anyone programmed one of these, how's it compare to using smaller shift registers like the 7hc595, I'm wondering why he choose this to program with, was it purely
to keep the size down, easier?
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I don't think you connected the grounds, Dave.
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Set it to 1028p high def (don't bother trying to play it if you can't)
Ok, I won't.
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Set it to 1028p high def (don't bother trying to play it if you can't)
Ok, I won't.

So Literal!

If you can't "play it" because your computer can't play it back without freezing your computer up... then don't, simply "pause it" then simply skip a frame at a time, until you see the images
you wish...

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Also Awol, why am i getting the feeling i'm being somewhat estalked?
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So, the Maxim 7221CMG, anyone programmed one of these, how's it compare to using smaller shift registers like the 7hc595, I'm wondering why he choose this to program with, was it purely
to keep the size down, easier?
An advantage of the MAX7221/MAX7219 is it's easy to program, easy to daisy-chain multiple devices together and once the LED pattern is uploaded to the chip it deals with all the LED multiplexing so you have no worry about timing issues you may get with shift registers.
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I don't think you connected the grounds, Dave.
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Also Awol, why am i getting the feeling i'm being somewhat estalked?
"No, that's perfectly normal paranoia. Everyone in the Universe gets that" - Slarty Bartfast.
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Also Awol, why am i getting the feeling i'm being somewhat estalked?
"No, that's perfectly normal paranoia. Everyone in the Universe gets that" - Slarty Bartfast.

Just because you're paranoid doesn't mean that everyone is not out to get you. smiley-wink

Good video, impressive project, nicely done.  @cj, check the playground, there are at least a couple libraries for the MAX7221 and its very similar sibling, MAX7219.
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MAX7219 & MAX7221 are communicated with exactly the same.
I prefer SPI for speed, but shiftout works as well.
MAX7221 has controlled edge transition rates to cut down on EMI.
Otherwise, both are programmed the same:

digitalWrite(CSpin, LOW);
SPI.transfer(registerAddress);
SPI.transfer(numberTo Transfer);
digitalwrite(CSpin, HIGH);

registerAddress varies from 00 to 15, per a table in the data sheet.
Address 1,2,3,4,5,6,7,8 are the data registers that each control a column of data in a matrix or a digit in a seven segment display.
9-15 are the setup ahead of time to indicate things like the decode mode for using your own font, how many columns are active, the brightness, etc. Generally all are sent out in void setup, with perhaps the  brightness changed under user control in void loop.
Address 0 is used for NOP when MAX7219/7221s are cascaded and you don't want device in the string to do anything.

I've used these in several projects and have not used any library. Once past setting up a couple of registers, you're just sending data out for a column. Library is overkill.
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