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Help with Modular Addict Control surface weird characters


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Hi!

We are building MIDIBox v4 from the PCBs ordered from Modular Adict https://modularaddict.com/midibox-seq-pcb
But could not find the instructions for this exact board (just Wilba's), and now we have a problem that it sends out weird messages to the STM32F4 core. The unit starts up fine, but as soon as any button is pressed or encoder turned, the screen gets weird characters and it seems all the controls are messed up.

We suspect the Resistor network might be the problem, that is not the same specification as needed, we used this: https://lomex.hu/pdf/(bou)_4600_serie.pdf

Also it is a question if the encoder pinout is correct and if it needs the arrangement suggested by Hawkeye in this comment? 

 

Any help please what is the problem? I attach the picture of the current stage of the PCB build.

IMG_2186.jpg

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With these "symptoms", it's most likely not the encoder pins not being crossed (but they should be, if you are using e.g. ALPS STEC12, @norbim1 found this out some years ago, thanks again!).
If the pins are not crossed, i only sometimes saw some slightly erratic encoder control, e.g. the cursor sometimes jumping two steps instead of one, when scrolling, but one could use the unit without big problems.

With this issue, i'd suspect a problem on the DIN side, check the 74HC165 shift registers and their respective pullup resistors/resistor networks. If the screen freezes up, make also sure you are feeding it the correct voltage (5V/3V3 jumper) and that your 5V PSU power rail is sufficiently stable, i've seen very cheap USB "phone charger" PSUs that would cause displays going scrambled, either they were overloaded from the beginning or they produced a lot of switcher noise on outputs.

Good luck and many greets!
Peter

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Measured the resistor network – they seem fine, every pin has 10k to the common pin. So the resistor network seems correct by measuring them. And it is 101 (bussed)...

It turned out the store mixed up the IC for the STM32F core (they gave us not the IC1 74HCT541, but 74HCT154). We bought the correct ICs, replaced them, but no luck, it gives the same erratic behaviour - buttons not triggering the right commands or pages... 

Any idea how we can troubleshoot the source of the problem?

Edited by BG
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@latigid on Thanks for the point, we tried with Wilba HWconfig, and it works! :happy:

What a relief... But in some forum post it was written that the Modularaddict board is for the Standard HW config.

Some good concise guide would be nice for the whole project :rolleyes:

Edited by BG
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