LED matrix display - MD_Parola, MD_MAX72xx and MD_MAXPanel

marco_c: I am guessing here that you are referring to the Parola modules and not Mel's clock project :-)

Hey, whatcha got against clocks with scrollie messages....LOL

As an aside, I wrote a Mac program that connects to the clock/scrolling message and allows me completely program it from the computer via bluetooth. I also put in an LDR so the project auto dims at night so as not to light up the room...:)

I did read that "interesting" line on page 2 as well. Confused the heck out of me. But then, for the most part, I confuse easy any way...

I used my 24 module to do a fake "NYSE" ticker for a friend...these Parola's are still a hoot to use...


OK, thanks for pointing that out. It was added by the staff at Tayda, I guess trying to be helpful.

It is now changed to

The video shows connections from a prototyping shield to connect the led matrices and the controls used to demonstrate the functionality of the software, but any of the usual connection methods will suffice.

The sensor shield is available a number of places, like on eBay http://www.ebay.com.au/itm/Sensor-Shield-V5-For-Arduino-APC220-Bluetooth-Analog-Module-Servo-Motor-TR-/310722948446?pt=AU_B_I_Electrical_Test_Equipment&hash=item485887ed5e. These shields standardise the digital and analog pins to a 3 pin interface (Ground, Voltage, Signal) so that standard connection wires (for example, http://www.ebay.com.au/itm/10pcs-3pin-20cm-2-54mm-Female-to-Female-jumper-wire-Dupont-cable-for-Arduino-/390556203029?pt=LH_DefaultDomain_0&hash=item5aeef6b815) can be used to rapidly connect sensors.

I build the simple circuits on small circuit boards (http://www.ebay.com.au/itm/GRS-24-X-1-Square-Prototype-Circuit-Board-Kit-PCB-Proto-/281140536860?pt=LH_DefaultDomain_0&hash=item417548261c) on which I mount a 3 pin connector for GVS. Boards have switches, LEDs, pots, lasers, IR detectors, Temp sensor, etc, mounted so that I have built a 'library' of standard modules that I can easily cable together to prototype ideas without fiddling with breadboard wires for the simple stuff. I also have some larger boards for LED display through 595 interfaces where the 595 inputs are GVS (3x3 pins) so that I can use these quickly as well.

Works for me and is completely reusable. You see the boards, with switches mounted, in the Parola video.

Hmm, re-reading that seems like a buy a lot of stuff on eBay.

marco_c: Hmm, re-reading that seems like a buy a lot of stuff on eBay.

It's OK Marco we won't tell your wife 8)

I have reworked the MD_MAX72xx libraries for Parola and the whole system can now run on the more generic hardware modules with connectors at the top and bottom. Library version 2.2 is available in the repository (link below). You need to use the compiler switch USE_PAROLA_HW to switch the code in the library between hardware types. Please read the accompanying html documentation.

Thanks to Mel for Beta testing!

Thanks Marco - that's going to be a very handy enhancement as I have a few of these laying about too.

Cheers ! Geoff

I just built eight of these modules with parts from ElectroDragon and it is easily the most satisfying Arduino project I've ever built. All I needed to do was change the message in the demo and the number of displays. The code compiled without error and worked at first go. The Electrodragon boards were modified slightly from the original to use wider traces for power and ground and data between modules. The supplied artwork can go directly to SeeedStudios for manufacture and the total cost was less than $30.00 for all eight of the modules I built... Wow, I got Blinken Lites...


strykeroz: Great stuff. Of course I'll have Popcorn playing on tight rotation on brain-FM now for the rest of the afternoon after your video :)

That song is a tango, believe it or not. At least I've heard it used as one.

Some basic questions:

1) How big are the displays? (I mean in millimeters) 2) At what frequency do the displays flicker? From what I understand, all such displays do flicker; it's just a question of at what rate. If the rate is poorly chosen, the display will be annoying if not painful to look at. 3) How would I go about changing the font?

Note: if the digits are not all the same width, then if you have a clock showing seconds, the numerals will jump around on you.

  1. The display matrix is about 1.2" square
  2. The MAX7219 datasheet says the refresh is minimum 500 Hz, typical 800 Hz. Animation speed depends on what the program does but it can run faster than you can read, for sure. These are definitely not painful on the eyes.
  3. Font file is in the library as data. Easy to change if you want to. If you do, send me a copy and it can be included in the main library.

Proportional and fixed width fonts are included. Text messages work best as proportional. Things like the time need a fixed font. The numerals only jump if you want them to.

I was so impressed with Marco's Parola for Arduino project that I have, with Crossroads invaluable help, designed a PCB that uses the larger 60 mm square LED matrices. Here is the thread where this is developed and once I have done some minor tidying up of the Eagle package Marco has kindly allowed me to put the files up on his Parola site for download. The final version of the Eagle files in reply # 28 of that thread are functional aside from the fact that the drill hole size for the sixteen LED matrix holes are marginally too small. This, along with some other minor cleaning up will be done before they are put up on the Parola site. Pedro.

EDIT - Marco has moved his Parola project to GitHub and consequently the Bigger Parola files have moved there too


Great work Pedro.

Now we have Mama Parola and Baby Parola. Who will do a Papa Parola? I am expecting window size :-)

How much to buy the things already assembled? Or at least with a circuit board already printed; I haven't the facilities for printing them.

Also, is there any intermediate size of matrix (maybe 40 or 50 millimeters) available?

check e-bay, several sizes are available. May not have the nice, neat interconnections, you'll have to take care of that.

got link to download this MD_MAX72xx.h ? :slight_smile:

wilson16: got link to download this MD_MAX72xx.h ? :)

It's a little tough to find on the CodePlex site but here's the link:



thank you very much :) :) :) :)

Marco has kindly allowed me to host my files for the Bigger Arduino V1 on his Github page here


The Eagle schematic and board files, seeedstudio gerbers and custom 8 x 8 LED matrix are all included.


I still have a bit more work to go but these "Mama Parola" 60 mm displays are looking good :D


Looks good Pedro - get a tripod for that camera tho & fire the cameraman :)

Too true Crossroads, I have been meaning to fire that guy for ages 8) And that was after a bit of Youtube video stabilisation too. I will have to shout myself a tripod for Christmas, which reminds me, all the best to you and your family for the festive season and stay safe, Pedro