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Topic: problem with the 8X8 linksprite clone led dot matrix board (Read 3482 times) previous topic - next topic

knuckles

Aug 20, 2014, 04:07 pm Last Edit: Aug 21, 2014, 06:14 pm by knuckles Reason: 1
i have hooked up 2 boards as shown in the instructions but the leds just stay on and the display is jumbled when they do flash
no letters and numbers .

its very straighforward just 3 wires to 8 9 and 10 and power and ground from the uno board so what could go wrong ??as shown in fact

http://linksprite.com/wiki/index.php5?title=LED_Matrix_Kit

Riva

Do you have the 8x8 LED matrix on the right way round?
Don't PM me for help as I will ignore it.

knuckles

#2
Aug 20, 2014, 07:19 pm Last Edit: Aug 20, 2014, 07:33 pm by knuckles Reason: 1
tried plugging it the other way round ,the supplier sent me another and thats the same so it appears ,not sure what is at fault .

actually its a clone . not sure if the max7219 ever are faulty

PaulRB

Hi, touch the soldering iron for a couple of seconds on each solder point, just long enough to melt the solder. All joints should look bright, although they will dull as they cool after a few seconds. You might just have a bad joint.

Paul

knuckles

i got rid of the ic socket and soldered the max chip in direct

Riva


i got rid of the ic socket and soldered the max chip in direct

A couple of probably stupid questions but...
Did you solder the chip in the correct way round?
Are you good at soldering as the IC could have been baked else?
Don't PM me for help as I will ignore it.

PaulRB


knuckles

#7
Aug 21, 2014, 06:08 pm Last Edit: Aug 21, 2014, 06:13 pm by knuckles Reason: 1
tried everything else to no avail ,but still the same some leds stay on all the time and no cycling thru the alphabet and numbers.
the 8x8 matrix progs from adafruit wont compile and spit out tons of error messages .
always the square pad is no 1 so its in right ,checked before soldering in

without the IC socket i can see and solder the legs at the thru hole pads on both sides.
and check for broken tracks . i had broken tracks on a mini board made by sparkfun before

PaulRB

Did the max chip have a dimple by pin 1? The fakes generally don't. I hve used a few '7219s in the past, none were genuine, no problems with any of them. Others have said the same thing. But I know some people have had problems with the fakes, so can't rule it out.

Lets see the sketch you are running. What version of the IDE are you using?

knuckles

no the max chip has no  dimple but 1 matches  the square pad

heres the code source i am using

http://www.linksprite.com/download/showdownload.php?lang=en&id=223

ide 1.05 r2

PaulRB

Sorry, I'm out of ideas. My suspicion at this point would be that I damaged the chip soldering it.

knuckles

both  boards are the same ,with the socket and now soldered in ,they perform the same ,some leds on all the time and cycles on occasion .they were both the same with sockets

PaulRB

Try using 3 different outputs from the Uno. Change them one at a time and test inbetween.

knuckles

#13
Aug 23, 2014, 12:01 pm Last Edit: Aug 23, 2014, 12:10 pm by knuckles Reason: 1
tried another set of progs but still the same just a few lines of leds  stay on all the time

http://www.instructables.com/id/LED-Matrix-with-Arduino/step2/Arduino-Library/

put it down to clone chips until i can get a genuine max chip to try from the seller on ebay

blurb from ebay seller of similar devices for future reference >>>>


8 X 8 LED dot matix display
Max7219 driver and board

This is a self assembly kit and requires soldering. The results however are worth it. It has 5 connections, 3 for SPI and +5v and Ground. These units can be daisy chained together to form complex displays.

work with Arduinos (see here) and have also been used with Raspberry Pi's (See here).

The kit includes:

   PCB, 5CM X 3.2CM
   2 5 way angled headers to connect to the module and daisy chain from.
   24 way IC socket.
   MAX7219 common cathode LED driver (Data sheet here)
   10uF electrolytic capacitor
   0.1uF ceramic capacitor
   10K Ohm resitor.
   2 X 8 way turned pin headers for the dot matrix display.
   8X8 red common cathode LED display, 3.2X3.2 CM

When built the module has an imput and output set of 5 way headers with pins as follows:

   VCC (5V)
   GND (Ground)
   DIN (Data In)
   CS (Chip select, also referred to as "load" in some libraries)
   CLK (Clock)

To assemble:

The board has silk screen printing which is clear on where things go, with the exception of the polarity of the electrolytic capacitor who's positive lead is, as you look at the top of the board, goes in the hole nearest C2.

We soldered in the in and out 5 way headers first, then the small components, the resistor, ceramic capacitor and electrolytic. Be careful with this, observing polarity of the electrolytic capacitor. Note also that we bent this over so it had no chance of fouling the LED display which plugs in directly above.

We then soldered the IC socket. When we soldered the headers for the LED display we plugged them into the display then inserted them into the board. This ensures they are square.

Inserting the MAX7219 is tricky. We find that most IC's supplied in DIP packages have their pins a little wider than the sockets they are supposed to go in. Place edge on a flat surface, and gently push the rows of pins together so that it fits.

When we built our test ones we plugged in the dot matix display the wrong way round. It displayed odd horzontal and vertical patterns. We the turned it around and all started working.

( this is my problem but turning it round it was the same ))


Please be careful with polarity. There isn't supposed to be any polarity protection in the MAX7219 so be careful. We did get away with it but may have damaged our chip. **
There are various Arduino libraries around, for example see the link at the top of this listing. We used the LedControlMS.h which we found here, and it works well.

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