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Topic: New around with a strange problem(8x8 matrix) (Read 3472 times) previous topic - next topic

sebulica

Hi to all around here :)

I've been interested in arduino for quite some time and i've bought one from ebay(arduini pro mini),along with a dual-color matrix(red and green) and 2 max7219.i've soldered them using schematics around here,but used only the red colour and one max.

my problem is that the matrix is not lighting up a single led.it lights up only rows.no lines,no dots,only rows.and sometimes from a row is shutting down an led,like it's supposed to light up only him and shut down the others.no matter what i try it only lights up rows.i've tryed different programs,libraries,rewiring,i've tested the matrix dot by dot and it's ok,i've tested arduino with single led light up and responds ok.

so,my question...the max7219 might be half-dead?or it's just me messing something up?

please help,i'm desperate.i'm searching and trying for a week now,and i can't figure it out....

CrossRoads

Post your schematic & code. We can only guess otherwise.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

fungus

max7219s don't usually work with multi-colored matrices.
Advanced Arduino

CrossRoads

They will work just fine when only one color is being driven.
Using 2 of them can be made to work; with the addition of diodes and time control of shutdown to allow multiplexing of the anode control; and requiring that common anode matrixes (same anode for red & green for example) be used.
I have previously posted how to do that, with schematics.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

sebulica

i've used the schematic from atachment.experimentaly i've noticed that if i connect the IRES to + the matrix stays on all the time but if i connect it to GND it lights on only the "commanded" leds.

the code was from examples for MD_MAX27xx test

i've connected the pins as requested in program.everything seems ok.but as i've told you it lights up only rows instead of single leds (i guess it "wants" to light single leds :D )

CrossRoads

So you have a like a 20K resistor from pin 18 to +5?
"IRES to +"
That resistor sets the max current flow to the LEDs.

"the code was from examples for MD_MAX27xx test"
Where is that code found?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

marco_c

@CrossRoads, MD_MAX72xx library has the test code for the library functions in sketch referred to by OP.
Arduino Libraries https://github.com/MajicDesigns?tab=Repositories
Parola for Arduino https://github.com/MajicDesigns/Parola
Arduino++ blog https://arduinoplusplus.wordpress.com

sebulica

#7
Dec 18, 2013, 10:35 am Last Edit: Dec 18, 2013, 10:43 am by sebulica Reason: 1
the code is big and i can't upload it here,but i will attach a text.

for IRES i've used a 100k variabil resistor but it was not working connected to VCC(+).so i've tryed to connect it to GND(-) and worked fine.

the leds are all lit up and i can't distinguish any movement if i connect it to +.but if i connect it to - the led stay shut and light up only lines.

i know it's a little bit tricky to use both colours at the same time,but i want for now to light up one colour and aquire some skills and experience in coding etc.but i can't make it work.

Paul__B

No, I give up on that.

You have posted a ".txt" file which appears to be somehow garbled, apparently a Windoze version, rather than the ".ino" file that was saved by the IDE and which can be imported.  I am unable to load it and compile it and have given up trying.

I cannot imagine what damage you might have done to the MAX7219 by connecting random things to pin 18 (or in fact, pin 18 to random things).  It should have a 10k resistor (20k will do) to the 5V line.  Never anything else.

sebulica

#9
Dec 18, 2013, 02:54 pm Last Edit: Dec 18, 2013, 03:44 pm by sebulica Reason: 1
strange as it sounds...sometimes when it's initializing it lights up random patterns on the matrix like a little square in the middle.first time i connected the max,and builted the circuit i connected a 50k resistor.all leds lit up.then i connected a 10k resistor and same thing happened.then i bought a 100k variable resistor and tryed to adjust to see if something happens,but nothing.then from a mistake  i pulled to hard on the wire and it broke from the board and touched the vcc pin.when it touched the gnd pin some of the leds turned off,and only lines were moving on the matrix.it looked like a loading bar then some lines randomly changing,guessing it was the program doing his thing.so it was more like a accidental descovery than random tryes.

i've checked the matrix led by led and it's ok,on both colours.i don't know if there is any way of testing the max2719...

marco_c

If you are using cheaper 'clone' chips for the MAX7219 then we have found this behaviour is common. See this thread http://forum.arduino.cc/index.php?topic=171056.0 and how we solve the problem (not ideal).
Arduino Libraries https://github.com/MajicDesigns?tab=Repositories
Parola for Arduino https://github.com/MajicDesigns/Parola
Arduino++ blog https://arduinoplusplus.wordpress.com

sebulica

yep...they were bought from ebay,verry cheap :P

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