RPI Pico W + 4067 multiplexer

[walrusmustgo]

Hello! First of all, i'd like to thank you for this wonderful project! It kickstarted my entry to the vast electronic world! ^^

With that being said, i'm a noob, just started fiddling with electronics. Now,i've got an issue with using multiplexers with the rpi pico w board. If i connect a single potentiometer to the ADC input of the Pico, everything is working correctly, but if i build a new firmware, with multiplexers enabled, i get really hectic behaviour once the pot gets under a certain threshold, as you can see here:

OpenDeck.configurator.-.Brave.2022-11-08.14-13-53.mp4

My board is setup correctly ( as far as i'm aware ):

This is the build config:

Upon measuring voltages, the pot sends good values to the multiplexer, but on the z0 pin, the voltages are much smaller ( 3.3V on the channel pin, ~0.8V on the signal pin ).

As i've said, i'm a noob, so i might be missing something fundamental/obvious! :)

Thanks again for this beautiful piece of software, and your hard work!

Regards, Marko.

PS. The breadboard image configuration is just one of many combinations i've tried. I've tried to fill all 16 channels with potentiometers as well, tried only using channel 0, only channel 16 etc. The behaviour is quite erratic, sometimes nothing gets picked up on channel 1, but gets picked up on channel 16. If i enable every channel, this jumping from channel to channel happens on all of them.

[paradajz]

Can you post your entire config file?

[walrusmustgo]

---
  mcu: "rp2040"
  usb: true
  uart:
    dinMIDI:
      pins:
        rx:
          port: "0"
          index: 1
        tx:
          port: "0"
          index: 0
    touchscreen:
      pins:
        rx:
          port: "0"
          index: 5
        tx:
          port: "0"
          index: 4
      components: 64
  i2c:
    display:
      pins:
        sda:
          port: "0"
          index: 16
        scl:
          port: "0"
          index: 17
  buttons:
    type: "native"
    extPullups: false
    pins:
    -
      port: "0"
      index: 2
    -
      port: "0"
      index: 3
    -
      port: "0"
      index: 6
    -
      port: "0"
      index: 7
    -
      port: "0"
      index: 8
    -
      port: "0"
      index: 9
    -
      port: "0"
      index: 10
    -
      port: "0"
      index: 11
    -
      port: "0"
      index: 12
    -
      port: "0"
      index: 13
  analog:
    type: "4067"
    inputVoltage: "3.3"
    multiplexers: 1
    pins:
      s0:
        port: "0"
        index: 18
      s1:
        port: "0"
        index: 19
      s2:
        port: "0"
        index: 20
      s3:
        port: "0"
        index: 21
      z0:
        port: "0"
        index: 26
  leds:
    external:
      type: "native"
      pins:
      -
        port: "0"
        index: 14
      -
        port: "0"
        index: 15
      -
        port: "0"
        index: 22
      -
        port: "0"
        index: 21
      -
        port: "0"
        index: 20
      -
        port: "0"
        index: 19
      -
        port: "0"
        index: 18

Here it is! :)

[paradajz]

You are sharing the pins between LEDs and multiplexers: pins 18, 19, 20 and 21 are defined both for LEDs and multiplexers. Remove the LED ones.

[walrusmustgo]

Oh my........ Thanks! I'm an idiot :)

It's getting better, but there's still some weird stuff happening:

1. If i turn channel 1 knob, i'm getting the correct channel readings ( channel 0 ), but the values are clamped to a really small value ( 27 - 32 ), and if i turn the channel 16 knob, i'm getting both channel 1 and channel 16 readings, with the same clamped values... The pots are 10K by the way, don't know if that matters :)

OpenDeck.configurator.-.Brave.2022-11-08.14-48-40.mp4

[paradajz]

Did you run make clean after you've changed the config file?

[walrusmustgo]

Tried it now, rebuilt, but the problem still persists :(

Do i have to play around with ADC offset by any chance?

[paradajz]

Do i have to play around with ADC offset by any chance?

No. Running the 4067 mux on that same ADC pin on my test setup works fine. My board is standard Pico, though, not the W version, so I'm not sure. Double check your mux wiring, maybe there's a loose contact somewhere.

[walrusmustgo]

Hmm, i'll try to reconnect everything and let you know. :) I'll also see if i can get ahold of a normal Pico board, the Pico W had some small firmware changes afaik, that might cause the issue (although, if i'm not mistaken, it's just some small internal tweaks).

I'll keep you posted once i test with new connections,and a Pico board. :) Thanks a lot!

[paradajz]

You should also tie any unconnected mux pins to GND - floating pins cause noise.

[walrusmustgo]

I've reconnected everything again with new cables, tried a different potentiometer, and connected all of the unused pins to the GND. The only thing that changed was that the clamped value vas lowered ( 25 - 30 )...

I'll try with a regular Pico board tonight, and i'll keep you posted :)

[paradajz]

Please also verify that you are on latest commit on master. After that, to rule out issues with the mux, disconnect Sx and common/signal/Z pins from Pico, tie all Sx pins to GND, and then measure the voltage on the signal pin when the pot on mux channel 0 is turned all the way left and right (so the voltage readouts should be 0V and 3.3V, respectively).

[walrusmustgo]

Alrighty!

1. The commit is latest, just tried cloning the repo again, did a git pull, no changes. Built again, the same issue.
2. I've tried 3 MUX boards with the method you've suggested, all mux boards display correct values (0V - ~3.3V)

I'm more and more starting to believe that it's the Pico W issue to be honest, I've tried building with different pins, some things have definitely changed for the Pico W board:

I'll know more tonight, if it's a Pico W issue, than i'll see if i can pinpoint the problem, and i'll let you know if i've fixed it! And i'll let you know if regular Pico is working correctly :)

By the way, i've changed my config to use 6, 7, 8, 9 ( and removed them from the button control list :) ) pins respectively for the control pins, because looking at the pinout, nothing has changed in that regard on the Pico W.

[paradajz]

Moved this to discussion as Pico W isn't officially supported.

[walrusmustgo]

Alrighty!

I didn't manage to get ahold of normal Pico yesterday, but will today, and let you know about my findings! :)

[walrusmustgo]

Okay, testing on the normal Pico board, the issue is same here as well... :( I honestly have no idea why is this happening, i've tried multiple different components, faders, 2 types of pots, 5 different mux boards, but it's always the same... I'll do a couple of more tests in the following days, and let you know about the results.

[paradajz]

Okay, what about this:

• Ground all Sx pins on multiplexer (don't connect them to Pico)
• Connect multiplexer common pin to ADC0/GP26
• Ground all multiplexer inputs except channel 0
• Enable only analog component 0 in web UI

Are the readings okay then?

[walrusmustgo]

It's this one:
https://novi.kupujemprodajem.com/elektronika-i-komponente/moduli-za-samoizgradnju/multiplekser-sa-16-kanala-cd74hc4067/oglas/32434646

[paradajz]

I'm thinking it maybe needs 5V for control, even though in theory it should work directly with 3.3V. Check what I did for my official OpenDeck boards here:

https://github.com/shanteacontrols/OpenDeck/blob/master/bin/sch/opendeck/v3.1.0/OpenDeck-r3.1.0.pdf

The mux is powered with 5V, and the pins for channel selection from MCU (RP2040) are first connected to 74HCT125 chip which I'm using as an voltage translator, so that the mux gets 0/5V for control instead of 0/3.3V. The analog inputs are still connected to 3.3V as that is the ADC voltage.

[walrusmustgo]

I see... Alright, i'll try to find the 74HCT125 chip tomorrow first thing, and i'll let you know once i've tried it!

Thanks immensely for your help, you're the man! :)

[paradajz]

Just be careful to get 74HCT125, not 74HC125 version.

[paradajz]

Did you manage to make it work?

[walrusmustgo]

Sorry, didn't manage ti try it yet, i've been waiting for the chips,and had ti leave for vacation :( Next week,i'll try it out,and let you know!

[MarkoKovachki-Starloop]

Alright, thanks a lot man! Just tried it out, and it's working like a peach! :) I've tried with 5 pots, all are reading correctly, the 5V solved it!

Thanks again!

Do you accept donations by any chance? :)

[paradajz]

Alright, thanks a lot man! Just tried it out, and it's working like a peach! :) I've tried with 5 pots, all are reading correctly, the 5V solved it!

Thanks again!

Great, thanks for the feedback. I've added a section on this problem in the wiki:
https://github.com/shanteacontrols/OpenDeck/wiki/Creating-custom-board-variant#a-note-on-multiplexers

A bit unrelated, but you might also find this connection scheme interesting (it's what I'm using on the official board which uses RP2040):
https://github.com/shanteacontrols/OpenDeck/wiki/Creating-custom-board-variant#mux-on-mux

Do you accept donations by any chance? :)

No. Appreciate you asking, though! I am making money on this project by selling hardware.

https://www.tindie.com/products/paradajz/opendeck-diy-midi-platform/
https://www.tindie.com/products/paradajz/opendeck-diy-midi-platform-v3/

The former board will be available in a month or so, while the latter will be available some time next week.

[walrusmustgo]

Great! Glad we've found the issue :)

Mux-on-mux will be the next one i test for sure! :D was really curious into how it will perform from the start, it's definitely my next step :)

[MarkoKovachki-Starloop]

Oh, also had one more question, is there any way to use multiplexers with digital pins as well? I've read that the 4051/4067 can multiplex digital inputs as well, so i'm wondering if there's a feature for something like that in opendeck? I'd like to multiplex some encoders as well...
Thanks! :)

[paradajz]

You can use analog input as button, but not as encoder. There's an option for that in WebUI. If your idea is to add more digital inputs, go with shift registers instead.

[eurorackworld]

Hey @walrusmustgo , the setup you've created is exactly what I want to do as well, but I don't know where to start with my RPI Pico (can't find the info how to flash/setup this board so Opendeck is on it). Could you help me by steering me into the right direction?

I've both various boards from @paradajz but want to make a small one using the RP2040, but went through all the documentation and don't know what info to use to get the board ready so I can configure it further via the online configurator.

[eurorackworld]

Just flashed the pico with the uf2 file, indeed works like a charm

Now I want to start using the mux, got major errors when doing the 'make TARGET=pico' command (I also never did this before, I just followed the instructions but the make command just throws error.

Story short, could anyone of you share your uf2 file with the mux configured as shown above? I did find the config file, don't even know how to edit, but I'll be fine on that one, but if already the make command fails, there is also no need to start caring about configuring it right...

[eurorackworld]

managed to edit the file via pico editor on my mac.

But the make call drops feedback like this:

/bin/sh: 0x0 + : syntax error: operand expected (error token is " ")
Starting build for pico
/bin/sh: 0x0 + : syntax error: operand expected (error token is " ")
make[1]: Nothing to be done for generate'. /bin/sh: 0x0 + : syntax error: operand expected (error token is " ") make[1]: Nothing to be done for pre-build'.
Building application...
/bin/sh: 0x0 + : syntax error: operand expected (error token is " ")
Building: board/common/Bootloader.cpp
board/common/Bootloader.cpp:39:44: error: argument to 'section' attribute is not valid for this target: mach-o section specifier requires a segment and section separated by a comma
uint32_t _flashSize attribute((section(".fwMetadata"))) attribute((used)) = 0;
^
board/common/Bootloader.cpp:46:56: error: expected expression
core::mcu::flash::read32(FLASH_ADDR_FW_METADATA, last);

and when using target mega2560 instead as a test, it's different and worse. Damn, final step of building it is blocking me from doing a build for the first time like this :P..

[eurorackworld]

nevermind the last remark on the config file, I leave my comment in her for a good laugh (.......).

Guess I have to pay someone to do a small favour for me of building an uf2 file :P (with various multiplexers for the analog controls, as the pico only has 3. So I guess 3x16=48 should be doable.)

[walrusmustgo]

I'll pack the files, no probs :D Sorry for the delay, was kinda busy the last few days... Anyways, i'll send the files tomorrow, got a bunch of configs built, i'll pack them as well :)

[eurorackworld]

Awesome! I get some help from Igor too, but I'll start with your files to not bother him too much :).

Thanks a lot for the effort, can wait to make a controller with this

[MarkoKovachki-Starloop]

Here are a couple of builds, a single mux, 2 mux, and mux-on-mux are here. Try them out and let me know! :)
pico-mux.zip

[eurorackworld]

hey thanks a lot! Do you you maybe have the original config files for these builds as well?

[MarkoKovachki-Starloop]

Here they are :) I've had only a single 4067 setup, but i've quickly added 2x4067 and a mux-on-mux option ( it's quite easy to make these config files, just copy the settings from opendeck yml files, and set the pins to your liking ).
pico-configs.zip

[eurorackworld]

haha thanks, that was fast. Yes I know how to edit the config files, but if I want to use your uf2 files I need to know on which pins you have your mux etc :P (I cannot see that in the uf2, at least I assume..)

[Bosswhite12]

Hello Marko. I have downloaded your Pico config files, thank you for posting those. Please could you tell me which Pi Pico pins I need to connect to S0,S1,S2 and S3? I only want to use one 4067 Multiplexer. Many Thanks

[Bosswhite12]

Hi I've just opened you config files and they have answered my question. Thanks

[MarkoKovachki-Starloop]

Yeap, hardly possible to see on the .uf2 file if i'm not mistaken :D But i'm not sure that these pins are correct honestly.. I can build a variant for you, just let me know which one? Btw, the single mux .uf2 file matches the config, but 2x4067 and mux-on-mux might not.

[eurorackworld]

Awesome, thanks for offering the support. @paradajz helped me out as well (as I'm failing to build the releases on my Mac. The final 'make' command fails in different ways depending on which target I choose). But I don't want to bother him all the time so great I can ask here/you as well! Appreciated!

[MarkoKovachki-Starloop]

No probs ^^ It's a kick-ass framework, it deserves all support it can get :) If you want me to build a variant, ping me, and i'll cook it up :)

[paradajz]

I forgot to mention that you can use Docker to build OpenDeck. In the root directory of repository, run this:

paradajz@desktop ~/dev/git/OpenDeck master*
> ./scripts/dev.sh 

It will download the container with the entire dev environment prepared - it's the same container the CI uses. You need to have both Docker and Docker Compose installed.

[Bosswhite12]

Hello would anyone in this thread be kind enough to make me a .uf2 file for a Pi pico controller with just three faders? I would happily send you a Paypal thank you. My config would be as shown below. Not sure if I need uart: .
Many thanks Nick

mcu: "rp2040"
usb: true
uart:
analog:
type: "native"
inputVoltage: "3.3"
pins:
-
port: "0"
index: 26
-
port: "0"
index: 27
-
port: "0"
index: 28