Problem with 8x8 Matrix and Parola, nothing displaying...

Hi folks I'm a noob to Arduino but I have been playing for the past week or so as I'm trying to use one together with AHK for a project I'm working on.

I have purchased some of the generic 8x8 matrices from ebay and downloaded Parola and the MD-MX79xx libraries and installed them but I cannot seem to get the matrix to display anything even just when trying the examples.

I have changed the header file in MD_MAX72xx.h so that the generic board is set to 1 and the Parola to 0.

I know the connections are fine and the pin numbers are correct as when I try the HW-Mapper in the examples I am getting the LEDs come on and do their thing across the matrix, I just don't get anything from the other examples (either the MD-MX72xx or Parola).

Is there something else obvious I am missing as I'm hitting a brick wall as to why it's not working. I've tried both with an Uno and also teensy 3.1 (via teensyduino).

I have managed to get the matrices working and scrolling text but this sadly wasn't using Parola, which is what I really want to use as it looks so good and customisable (and therefore perfect for what I'm wanting).

Any help or pointers would be much appreciated.

Thanks

Ells

I attached a picture of the wiring for the eBay modules.

Macro just updated the Parola and MD libraries a few days ago (version 2.4). Download it from his source code section on CodePlex:

I tested the Scrolling example sketch and all you have to do is set the number of displays you have connected.

I’m not sure that a Teensy can be used or not, but I’ve used the UNO and MEGA with complete success.

Mel

Thanks Mel,

I have it wired up as per your pic and downloaded the newest version as suggested but still nothing!

I have 6 of these things and can’t get a single one working let alone all six together using the libraries which is what I was hoping to do.

I know the matrices are all working as the HW_Mapper works from the MD-MX72XX libraries and also my other code that I found on here in another post that uses LED control to scrolls works (just with that it’s 90º wrong way with the generics) but I would ideally like to be able to scroll and just print in the correct orientation which is why I’ve tried to turn to Parola.

For some reason these libraries just don’t seem to work for me.

The only thing I can guess then, is that whatever generic modules you have must be different than the ones the rest of us are using. Have you got a link to the modules you got and a schematic or data sheet on them?

Mel

The one's I'm using are from these guys (albeit via their ebay store)

http://hobbycomponents.com/index.php/max7219-serial-dot-matrix-display-module.html

no data sheet that I can find on there.

Cheers

Looks pretty much like my eBay ones. Wiring on UNO is:

Pin 13 --> CLK
Pin 11 --> DIN (not DOUT)
Pin 10 --> CS

Modules are wired from right to left (facing them). So the first module connected to the Arduino is extreme right, then you jumper to the left each time you add a new one.

With the 7219 chip at the top as shown in my photo, look at the matrix. Facing it. On the left hand side of the matrix should be the part number (something like FJS1088AH). You can see that number if you look between my two modules. I've seen them installed backwards from eBay a few times.

You don't have any other SPI devices attached at the same time do you? Like an ethernet shield or something? Attach a photo of your Arduino and modules.

As a last resort, you can ask Macro since he's the one who wrote the Parola library.

Mel

Problem solved!

I uninstalled arduino and teensyduino and reinstalled them one at a time and this time only added neopixel library that’s included with the teensy (as thas all I need) and so far it’s working like a dream. I can only put it down to a conflict somehow of libraries that installed with teensyduino originally.

Thanks again Mel for your help trying to get me sorted.

Now is there anyway of getting this to work with common anode as I have seen some cool blue matrices but they are only in CA and not CC :wink:

Good find on the library conflict! I don't have any Teensy's here, where space is a concern I use either MINI's, and Pro Micro's cause they're inexpensive.

If you mean those smaller PCB and blue 8x8 matrix modules from eBay, I think they first appeared here:

I have four of them here, just test connected them and they work fine if you edit the MXXX7219 library the same as for the other eBay modules.

Mel

Generally common anode or common cathode doesn't make a difference to the libraries except that the module orientation will change. The new version of the libraries includes changes to make the adaptation for novel arrangements much easier.

Thanks Marco, I'm a bit confused though as to what I need to change to get them to work.

I now have the CA ones and I am using the generic modules (which worked fine with the CC ones I had). At the moment I am getting moving lights across them but no actual characters which are moving very fast, I have tried changing the header file for the board type but this hasn't changed them.

Thanks

I don’t think that you can just change the LED modules and expect it to work. The matrix itself is wired differently and the circuit from the MAX7219 chip has to take that into account. The software will then accommodate the different row/column orientation that may result.