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Topic: 8x8 Matrix/MAX7219 chip Broken? (Read 1 time) previous topic - next topic

MrWizerd

Hello, I have a problem and it is the first I have run into while testing the modules I have for my Arduino.  I currently have an 8x8 Matrix that when powered and connected to my Arduino NANO's pins 10=load, 11-clk, and 12-datain light up rows 1, 3,4,5,7, and 8.  then the LEDS in rows 2 and 6 dance there lights.  I believe that they might be following the pattern correctly but I can not be sure.

The chip is a MAX7219 and the array and chip were placed on standoffs that were soldered in place to avoid heat damage.  I believe that the pins are addressed correctly as pins d13 and d10 were used to blink a single led and were addressed as just pin 13, and 10 respectively.  This means that pins 10-12 which are connected to load, clock, datain and are referenced in the sketch this way should be correct.  But I am not positive that the UNO and NANO's pins are referanced the same, because I don't have enough experience with these boards yet.  This is my first time trying to use the Arduino to test the different modules I have collected over the last few weeks.

Has anyone seen this problem before, could it be the MAX7219?  Is there a way to test the 7219? or would it just be easier to run to radio shack and pickup another 7219 and see if that solves the problem?

this is a picture of it while its supposed to be doing the demo.


PaulRB

Hi,

Uno and Nano are pretty much identical in terms of pins, certainly the way you're using them. If there was a problem with those pins, all the leds would be "dancing", but most of them are OK. This points, in my mind, to problems in the connectors between the max chip and the display. Did you built it from a kit? "Dry joints" are my guess. Go over them all again with the iron and an extra spot of solder. Another possibility is those sockets/standoffs, especially between the board and display. The pins on those displays are not designed for sockets, so may not be mking good contact, especially if some are a fraction shorter than others.

Paul

Paul__B

#2
Jul 26, 2015, 10:34 am Last Edit: Jul 26, 2015, 10:39 am by Paul__B
Right, now, here we go.

This is clearly one of the modules readily available on eBay and you have apparently assembled it yourself.

The first thing is that the matrix must be inserted such that the writing is on the right hand side as you see it in your photograph.

I seem to recall that there are some variants with two of the control lines swapped in position on the edge header, but if you follow the markings, that should not be a problem.

I also notice that that particular type of module is advertised much less now in favour of ones such as this:

Just as well, as the older type is not properly stackable.

Apart from that, you need to post the code that you are actually using, using "code" tags - the first icon above the reply window.

And I do not see how the use of socket pins protects against external heat sources.

PaulRB

And I do not see how the use of socket pins protects against external heat sources.
I think the OP meant during soldering.

Riva

I think the OP meant during soldering.
That confused me for a bit.  :smiley-confuse:  I thought you had started quoting yourself but then noticed the subtle name difference.  :) 
Don't PM me for help as I will ignore it.

Paul__B

That confused me for a bit.  :smiley-confuse:  I thought you had started quoting yourself but then noticed the subtle name difference.  :)  
Name?

I thought the avatar was - well, somewhat - more obvious! :smiley-roll:

PaulRB

I thought the avatar was - well, somewhat - more obvious! :smiley-roll:
My avatar doesn't show next to my posts, although it does show in a circle on the menu bar at the top-right of the page. Any ideas why?

Paul__B

Far be it from me to even begin to understand the deep secrets and mysteries behind the Arduino.cc Web server! :smiley-eek:

Francesca79

Has anyone seen this problem before, could it be the MAX7219?  Is there a way to test the 7219? or would it just be easier to run to radio shack and pickup another 7219 and see if that solves the problem?
I had the same problem, until I took the dot matrix off from its board and rotated it 180 degrees and put it back on. Now it works fine! ;) It came assembled the wrong way around I guess...

Cheers!

jcristin

I had the same problem with a 4 display unit. They were were all mounted the wrong way. Just turned 180 degrees round and started working perfectly. Good Chinese friends :)

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