I soldered the arrays myself. As you can see by the picture, i got two of them to function properly. The other three i made have a scrambled image when it runs. The code is working properly. I figure this must be due to a contact problem with the led array itself. I reflowed the solder connections to no effect. I switch to a new 8x8. Four of them result in the same.
What can i do to get these remaining 8x8s to function properly? How do i ensure better contact when i plug in the 8x8 to the backpack?
Are you sure they're not in backwards? Either IC or LED module? Did you try swapping a working and non-working module to make sure it's not the wiring?
Yea, yes, yes and yes. If the areay were in backwards, all lights would be solid on.
The IC is in according to schematic. Notches lined up. I've even tried taking the IC in and out of socket a few times.
I have taken the 8x8 array from a working module and put it on the nonworking ones. The image is still scrambled. I will tey swapping around a few more times just to check. Ive checked the wiring and the code for correcr pims several times.
Other than loose contact with the 8x8, I dont know what else could cause this problem.
I wonder if i slather a bit of solder past into the pins and hit it with a heat gun if it would make a stronger contact?
OK, you do not understand how these arrays work. never mind.
I notice that it is the first display in a chain of three and the following ones operate correctly. This strongly suggests that the IC itself is working. We would need to see your code, but an alternate way to look at it would be to swap the module's position in the chain. I would like to know the result of that manoeuvre before making further suggestions.
Note that he said he had swapped the display matrices and the fault remained with the module, not the matrix. If a 1088B matrix is inserted instead of the correct 1088A, you will get all LEDs lit. The partial pattern in the OP more resembles the result of inserting the matrix rotated 180°.
I want to hear what happens when the module is moved to a different position in the chain. If the problem remains with the position, the code will be the problem.
This does not guarantee trouble-free operation. I had a problem when I used only 1 such LED module. At the beginning of my program I also set the minimum brightness, but still in most cases things did not go as they should and I had to restart the microcontroller several times.
The swap that you say you did, is not the one I wanted you to make. So your answer is really "yes, yes, no". The idea was to check the wiring, by exchanging full modules. That was requested again in reply #9.
I do not think there should be a power issue, as these modules normally draw modest current. But that doesn't mean that the wiring in this particular installation is good.
I have observed, in the two modules that work correctly, when power is first applied all leds are off until i hit reset to wake them. That is in the code.
Now, for the nonworking modules i flipped them so the notch is on the same side as the working ones. When power is applied, all leds are On instead of off. This could be the solution, but im not sure how to go about it.
I did as suggested and changed the order of the modules. Two working in front, nonworking in third. The good ones still function as they should. I rotated the bad module array 180 degrees. All leds are On when power is applied and they stay on. The working modules are off when power is applied and must be woke up. Maybe this is something wrong with the modules wake function somehow being backwards?
Is the power conducted through the modules? In other words, "daisy chained" from one module to the next? Try running power directly to each module instead.
Also, please test each module individually, so the processor is only driving one module. Segregate the working and non-working modules. If they all work, then go back to troubleshooting them as a group.
When troubleshooting, it's best not to change too many factors at one time. If you do, you won't be sure which change made it work or not work.
OK, so the code is not the problem, it is the modules. Summarising the situation, I missed it in the first post, but you have two working and three faulty modules. So all faulty modules behave in the same fashion, swapping display matrices demonstrates it is the module at fault, not the display matrix.
OK, so the displays are socketed - as they should be. And the ICs are socketed which would not usually be such a concern. So have you tried exchanging the ICs between working and non-working modules? Clearly that is the next step. You use a small blade screwdriver to carefully lift from one end just a little and work it under the whole IC to lift it evenly. (No, I see you have mastered this!)
That will be the final "reveal". If it (unlikely) proves to be the PCB, then are they all identical? If it is the ICs, well that is clearly unfixable and you will have apparently received "fake" MAX7219s!
That actually suggests a different PCB pattern, designed for the "B" matrix!
Don't try and explain it!
Errr, no! Contact problems would never cause this effect.
As suggested, i popped out and switched ICs from a working module to a nonworking one. All three max7419s i put into the working module functioned as they should. The ic i took from the working module imto another one still only lit up all the leds. Even after a few resets. To dpuble check again, i took an array off a working one and moved it to another.... And it worked! So it appears that i have two normal arrays, and three crap ones that dont function for some reason.
I got them as kits from amazon. Pwrhaps ots time for a refund
I stopped daisy chaining them together and just did one at a time. Does the IC in each module control each one individually? Or if i just chained them together with vcc and grd if the first would drive them all?
