Cheap MAX7219 LED Matrix Module - faulty?

nanawhite

Newly Enlightened
Joined
Jun 13, 2017
Messages
1
Hi,
I have been trying to get three cheap, "New MAX7219 (here is the max7219 datasheet)
Dot led matrix module MCU control LED Display modules for Arduino" from eBay to work with an Arduino UNO. I've tried a lot of different sketches and wiring options, and followed different manuals. Whatever I do, i only get the following pattern (also when just connected with power): http://i.imgur.com/erguHSs.jpg




The description does not make me much wiser:
Module parameters:

  1. A single module can drive an 8 * 8 common cathode lattice
  2. Module Operating voltage: 5V.
  3. Module size: 5 cm long X 3.2 cm wide X 1.5 cm high
  4. With four screws hole, aperture 3mm, by using our M3 Tongzhu fixed
  5. Module with input and output interfaces, supports multiple modules cascade
  6. Led colour:Red
Wiring instructions:

  1. The module left as an input port to the output port on the right.
  2. The control of a single module, simply input port to the CPU
  3. Multiple modules cascade input termination CPU, 2 output termination module, a module of the input of the input terminal, the output terminal of the first two modules of the first three modules, and so on ... 51 MCU, for example: VCC → 5V GND → GND DIN → P22 CS → P21 CLK → P20
I ordered three, and I get the same pattern on all of them. I do have another module (4 chained 8x8) display that works with the same sketches, also from eBay but with a blue PCB (vs. this green one, if that indicates som known fact about these displays).
Am I missing some key piece of information here, or is it faulty?
 

drm1

Newly Enlightened
Joined
Jul 6, 2017
Messages
1
Ran into the same problem. There are two factors:

1. Matrix must be powered from 5V; output from the regulated 3.3V on a 3.3V board will probably not work. Check Vcc going to the display.

2. LED matrices often come plugged in backwards. If the connection pins (display 0 end) are pointing down and the LEDs are facing you, the tab and stamped numbers need to be on the left. Check that the displays are the right way around.

Hope this helps. --drm1


Hi,
I have been trying to get three cheap, "New MAX7219 (here is the max7219 datasheet)
Dot led matrix module MCU control LED Display modules for Arduino" from eBay to work with an Arduino UNO. I've tried a lot of different sketches and wiring options, and followed different manuals. Whatever I do, i only get the following pattern (also when just connected with power): http://i.imgur.com/erguHSs.jpg


 
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