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DMD voltage issue with 2.49v of Pin2DMD

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Hi !

I recently buy modules for DIY pin2dmd

Modules that I receive it's not RGB but GRB but, no matter, juste some wire to swap.
BUT... my probleme is :

When I use 5V power supply on this  DMD
Dmd connected with my STM32F4 Disc1 Discovery board (programmed with 2.49 Firmware of pin2dmd and upgraded from V2.J25.M14STM32 Debug+Mass Storage to V2.J29.M18)
Impossible to have a correct display, only some line groupe, red, green blue... random on the display module with High luminosity.
BUT, when i use a 3.3V instead of 5V to power the DMD. The display is correct.

Below 3.3V, the color is not good (turn to red color)
And over 3.3V, display nothing or some group of line very high very bright.

With or without sd card with registration key do the same.

The seller tells me that it comes from the firmware used in STM32F4

I have not yet tested old firmware version.


Your opinion ?
Mine it's a electric problem on this DMD but, I'm not sure.


Thks a lot every body



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With v2.49 you don’t need to swap cables anymore. Please try with original pinout.

I don’t know about the electrical differences of this particular panel so it could be helpful to have a picture of the back of these ;)


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2 pictures join in this message.
As you can see, with straight cable, the Red and Green are inverted (I have also the confirmation of that of seller)
but with swap pin 1-2 & 4-5(so pd0-pd1 and pd5-pd6), the color is now good (no picture join).

Second picture you can see the DMD PCB. (P2.5 (2020)-16S-V1.0
With 3.3V of ATX power, the display is correct.

I trying a lot of 5V power supply and so, always the same problem, don't work with 5V
very strange....




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You can use the config menu to correct the numbering of the colors! ;)
Press menu and option button at the same time to reboot the controller. Keep menu button pressed during boot to enter the config menu.

With pressing the menu button you can cycle trough the various menu points like pinball system, rgb sequence (this is what you need!!!) etc.
with the option button you can cycle trough the various options of each menu point.
Don’t forget to save your config!!!

I have the same panels here from a very old batch. Will try them tomorrow morning if they have the same issue with voltages.


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Ahh ! Ok, it's possible to change directly the configuration into a hardware menu.
I don't know that, great :)
Thks for this information ;)

I orde this DMD last month but, the seller tell me, they are not batch for 1/16 (because hardware instability problem)
So he propose me a 1/32 but, normaly, the 1/32 don't work, so I insist to have a 1/16 or refund
And so, it's send me I think  what was left in stock !

Yes, If you can check if you have the same issue it will be great, Thks a lot.

You can see (picture here) the display I have with 5V
I needed to put several sheets to take the picture becausse it was very too bright
And you see, no picture, just some group of line.


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PCB : P2.5(2020)-16S-V1.0

UR1, UG1, UB1, UR2, UG2, UB2,UR3,UG3,UR4,UG4,UB4, UR5, UG5, UB5, UR6, UG6, UB6,UR7,UG7,UR8,UG8,UB8 : CHIPONE ICN2026DP C CF 1J15.1
U1, U2, U3 : SUM 74HC245T D1409AFP81
a couple of 16 : 4953 4K2501
x2 (below  C29) : DP74HC138 4J2101
cx3, cx4 : 220ùF 10V
a lot of capacitor cmd : C1->C29
(not measured )
a lot of resistor cmd : mark 29B (not measured but normaly 1.96Kohm)

I thinks, it's all

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I think it could a problem of the 74HC245T bus transceivers not recognizing the 3.3V high levels with a 5V supply voltage correctly. We had similar problems with very old panels and that is why we added 74HC245 on earlier pin2dmd shields.  We removed them because newer panels did not need them because of the use of more 3,3V tolerant ICs (e.g 74HCT245). You can get around this problem by either getting a old shield pcb from uncle sash or rappelbox or using a power supply with adjustable output voltage. 4,5V should also work.

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Yes, if I remember the HCT chip are used because they are faster in I/O
But, I don't have the good H/W to desoldering and re- soldering this.
I can try but... not sure about the resultat and especially, I don't have a 74HCT245 in cms.
I have a lot in normal socket ;), but not in CMS.
I can of course order this, but it's very difficult if I don't have exactly a good a soldering station with his tools  for cms.

But, finaly, If it's work good with 3.3V... so...I can use 3.3V of my atx power suply.


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?? The seller tell me old me the opposite :lol:
I have more confidence in you, It's certain.

I will see with the seller if he can have me recent dmd 1/16, but he's not technical :(
Tell him about 74HC245T, 74HCT245 ...it's like...recite a poem to a cow.
It's coool but...
it does not help much.

Ok, Thks

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