Custom Wiring Questions

Hey all,

first of all great project. Made me go back into building stuff and making music, BUT…

got a zynthian build which is only partial working.
I have an all in one module with the basic wiring kit, waveshares 5" screen, hifiberry dac+ adc and raspberry pi 3b+.

Got it working EXCEPT that encoders 3&4 are not working ever… gpio i2c recognizes mpc 23017 working.

Switched working encoders for non working and found out its Not this…

Checked soldering, cant find any issues.

So my question for you is this:

Since i am planning to use it mainly with midi over usb and the rca outs, is it possible to wire the encoders straight to the header of the hifiberry?

And if so, how do i configure the custom webconf? Meaning which numbers… to be honest, this confuses me a lot.

Any help appreciated a lot!!!

Keep building epic shit!!

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Hi @Anaximander78! Welcome on board!! :wink:

So you can’t get working encoders 3 & 4, but encoders 1 & 2 works OK … well … your problem seems to be related with one of the interrupt pins, the B.

Take a look to this:

Could you give us more details about your build?

  • What SD-image are you using?
  • What wiring layout did you choose on the webconf? A screenshot from the dashboard would help a lot …
  • Some detailed photos from your build can help too …

Regarding your question about using the RBPi pins for the encoders, of course is possible. In fact the zynthian v1 worked on this way, and all the wiring layouts starting with “PROTOTYPE” use this kind of wiring. Anyway, i would suggest you insist with the MCP23017 …


Thanks for answering!

I am on a road trip right now so i have no pictures until tuesday.

I am using 2020-05 buster with the webconf using mcp 23017_encoders (also tried extra), and the appropriate setting for the hifiberry and the waveshare… also tried the stretch build 2019-06

Thanks again

So if understand correctly the B pin might be “broken” in some way?

Best rehards

it seems like that … broken or badly soldered :wink:
Did you double-check the soldering?


Definetely gonna double check tuesday. Thank you for taking the time!!

So here are some pictures. I replaced pin 37 an resoldered. Still nothing.

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My soldering doesnt look too good, i know. But everything else works. Since this is my second all in one pcb i guess i have to live with the working 2 encoders and make the rest via touch/keyboard.

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This is my webconf

Do the encoders work if you swap them, i.e. does nothing work connected to those encoder 3 & 4 inputs?

Do you have a multimeter with continuity mode? If you do, you can hold it against one of the encoder pins and the common pin. While holding it there, rotate the encoder. You should hear a short beep whenever you click the encoder.

Test both encoder inputs (A and B) this way. Start at the encoder itself, then test again on the bottom of your PCB, where the cables come in. Also check continuity onto the MPC IC itself (from the top, by poking the socket). Use the schematic to check what pins they should be.

That way you can rule out cable/soldering problems.

Thank you very much. I never worked with a multimeter, but this sounds like the way to go. Already tried swapping encoders.

It will take me some days, but i will report back.

I have to say this is a nice forum! Miles away from something like the ArchLinux Community… if you know what i mean.

With common pin you mean the ground pin?

Hi @Anaximander78!

Your soldering is far from good, my friend :yum:
It seems like some of the solder-pads are broken and a few solder points doesn’t seem very reliable:

It’s difficult to say with just a photo, but i would try to improve the soldering on the marked points, and perhaps others too. Of course, the multimeter could be your best friend in this case, specially for testing “continuity” …

Anyway, if you don’t get the 4 encoders working OK, we could arrange the better way to get your zynthian working 100%. You could try to solder a new one, or perhaps a pre-soldered PCB. I think i’ve some spare pre-soldered PCBs … :wink:

Good luck!!

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That is supernice! Tomorrow i can get my hands on a multimeter. Will try this plus resoldering. I think have to go back to a basic class in soldering… .

In case you have a presoldered pcb that would be awesome. Just tell me where to wire a little money.

Thanks again for your support, zynthians!

A solder sucker is a handy tool . . .

Hey i already suck at soldering!!


Kidding… this for the desoldering mess, right

Yes, it’s difficult to get solder, even when molten, off a board and the blob when formed can run across tracks. You can use a bit of multi strand wire but it’s not ideal.
A solder sucker is the right tool.

I appreciate that, thanks.

Just in case and in relation to my first post, i would use this to go the route without the all-in-one pcb:


If so, could i choose “Prototype” in the webconf and be good?

So i managed to kill my second all in one pcb. There was solder under the mcp making connections from inside… i dont know how i managed to do that. Then foolishly tried to desolder the whole module… stupid idea.

I think no solder sucker can repair this (i cannot for sure). I really underestimated this. Back in the late 90s i used to rewire the guitars of my friends, but this zynthian is another level. Its way more delicate than 10-15 wires with some potentiometers. I should have practised more soldering before this.

Anyway, reading through some threads about the Prototypes-Wiring made clear that i have to learn more about everything and made clear i should have ordered the kit alltogether.

So whats left in my ballpark is to use jumper cables to connect the encoders to the header of the Hifiberry and play around with the webconf.

Wish me luck and thanks for all your help.

I have been there as well. That’s why I use sockets now.