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Max7219 segments stuck in display test mode.

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 Ace
(@ace)
New Member
Joined: 5 years ago
Posts: 3
Topic starter  

I just bought a couple of those displays..and there is a problem with some new batches..

It seem they are stuck in display test mode.

 

Found this solution on an arduino Help page.

 

Your MAX7219 is in Display Test Mode.
Write a zero to the Display Test Register (0x0F) to get it out of Display Test Mode.

You may want to do some more initialisation:

Display Test (0x0F) = 0
Shutdown (0x0C) = 1  (0 for shutdown, 1 for normal operation)
Decode Mode (0x09) = 0
Scan Limit (0x0B) = 4 (to scan only 5 digits in your case)
Intensity (0x0A) = 0x01 (low) .. 0x0F (high)

Can you please fix this.

Cant code for shit myself..have no clue what to do : )

//Ake S

This topic was modified 5 years ago 2 times by Ace

   
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(@admin5435)
Prominent Member Admin
Joined: 7 years ago
Posts: 732
 

Hello ! I don't think it's the cause, I checked the library and everything is already set to disable test mode, 

In this case OP_DISPLAYTEST = 15 (0x0F) is set to 0 as you pointed.
Make sure to double check the pin ordering and solders if you have some, Since it's indeed the default mode when powering it means that the arduino can't initialize the display, so there is an issue with one of the two data pins. Or maybe a bad batch, but I'm playing with those displays since 5 years now and it's eeeexxxxxtreeemely rare for this particular kind of modules.

 


   
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