Shift Register Buttons Not Triggering Properly (RP2040, OpenDeck v7.10)

[kelvinyap9]

Custom Firmware on v7.10 - RP2040 (Raspberry Pi Pico)

Problem:

I can’t seem to get any pins on the shift register (74HC165N) to trigger a button (no light-up in the web config), except for Pin 6 (H), which always triggers Button 0.

This behavior is consistent with or without daisy-chaining the shift registers:
• With one shift register: Only Pin H (Pin 6) triggers Button 0.
• With two daisy-chained registers: Only Pin H on the second register triggers Button 0.

No other pins trigger any buttons.

Could this issue be caused by a timing mismatch (e.g., clock or latch signals)? Am I missing something in the YAML or wiring?

What I’ve Tested:

Multimeter Test:

• All button pins (A–H) idle at 3.3V (HIGH) and drop to 0V (LOW) when shorted to ground (button pressed).
  This confirms pull-up resistors are working as expected.

Shift Register Behavior Without Daisy-Chaining:

• Same issue persists: Only Pin H (Pin 6) triggers Button 0.

---

YAML

mcu: "rp2040"
usb: true
uart:
  dinMIDI:
    pins:
      rx:
        port: "0"
        index: 1
      tx:
        port: "0"
        index: 0
buttons:
  type: "shiftRegister"
  shiftRegisters: 2
  pins:
    data:
      port: "0"
      index: 11
    clock:
      port: "0"
      index: 12
    latch:
      port: "0"
      index: 13
analog:
  type: "4067"
  inputVoltage: "3.3"
  multiplexers: 2
  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
    z1:
      port: "0"
      index: 27

---

Wiring:

Shift Register → Pico

Pin 1 (SH/LD - Latch) → GP13
Pin 2 (CLK - Clock) → GP12
Pin 9 (QH - Data Out) → GP11
Pins 3, 4, 5, 6, 11, 12, 13, 14 (A–H) → Buttons with 10kΩ pull-up resistors to 3.3V
Pin 16 (VCC) → Pico 3.3V
Pin 8 (GND) → Pico GND

I should also mentioned that I removed the following keys in my firmware (I'm not using these components) which were present in the pico.yaml which I used as a reference:

uart:
- touchscreen
- i2c

leds:

test: true (what is this?)

indexing (I see this in the opendeck board yaml for rp2040 but saw in another post in this discussion forum to not use undocumented keys)

I also added inputVoltage: 3.3" under analog. Should I leave that in or remove it?

Can I also remove dinMIDI ? I wasn't sure if that was just a pin allocated to physical MIDI ports. I don't plan to use it for that purpose as I just want this to be a USB-only MIDI controller.

Thanks!

[kelvinyap9]

For more context:

I built the firmware in Ubuntu 22.04 which I ran in a UTM VM on an Apple Silicon Mac with the docker dependencies installed, added my user to docker group, and following the instructions to clone the git, run the dev.sh script environment, make clean when I change anything in the yaml before I do make TARGET=blabla.yaml which spits out the build folder.

I then flashed the merged.uf2 onto the Pico.

I'm also using this shift register diagram as a reference, hence the "Pins A to H".

[kelvinyap9]

In an attempt to isolate this issue even further, I'm now using a very minimal yaml config with just 1x shift register, and no multiplexers.

mcu: "rp2040"
usb: true
buttons:
  type: "shiftRegister"
  shiftRegisters: 1
  pins:
    data:
      port: "0"
      index: 11
    clock:
      port: "0"
      index: 12
    latch:
      port: "0"
      index: 13

Interestingly, now only Pin 14 (D) and 6 (H) work. The others still nothing. Also tested with my other shift register to rule out faulty registers - same result, only Pin 14 and 6 trigger buttons.

Re-tested with multimeter and button presses definitely drop the voltage from HIGH to LOW - exactly same behaviour for non-working and working pins. I've also ruled out it's not a physical faulty button by using a wire to short the A-H input pins to GND to simulate a button press.

[paradajz]

Pin 15 on the shift register needs to be connected to GND.

[kelvinyap9]

The program change offset is similar to what you want yes, but not applicable in this scenario since it only affects program change.

I'm guessing this also means there's no way to implement a "SHIFT" button like on the Pioneer DDJ controllers, as that would mean temporarily sending a different MIDI ID when another button is held down.

e.g.
HOT CUE 1 Button = Set Hot Cue 1 / Play Hot Cue 1
SHIFT + HOT CUE 1 Button = Delete Hot Cue 1

This option is not available in the firmware.

Do you have any other recommended ways to achieve something similar? Would be awesome to be able to expand a button to more than just "one role". I'm hoping to replicate the banks a DJ TechTools MIDI Fighter has:

https://www.djtechtools.com/downloads/documents/Midi%20Fighter%203D%20MIDI%20Map%20TRAKTOR.pdf

I don't understand if you have resistor connected or not? It's pull-down, not pull-up.

Oh, so it's pull-DOWN for a button on an analog multiplexer. I connected a pull-UP resistor thinking it was the same as on the shift register. Will test when I get home. Thanks!

inputVoltage is relevant only for nRF52 boards.

FYI building will fail if I don't specify inputVoltage: "3.3" under analog for rp2040.

/home/ubuntu/workspace/OpenDeck/src/firmware/board/src/common/io/analog/Multiplexer.cpp:63:38: error: 'PROJECT_TARGET_ADC_INPUT_VOLTAGE' was not declared in this scope
   63 |         adcConfiguration.voltage   = PROJECT_TARGET_ADC_INPUT_VOLTAGE;

[kelvinyap9]

Screen.Recording.2024-11-30.at.02.24.35.mov

This is what I mean when I set an analog as a "button" and it "refreshes" about twice a second. Notice how it's not floating state because if I set it as a Note, it doesn't detect any inputs, but as soon as I change it to button it flashes.

The pin from mux is currently shorted to Pico GND for testing.

What could be causing this?

[paradajz]

What could be causing this?

A bug. Fixed now on master branch.

[kelvinyap9]

A bug. Fixed now on master branch.

Awesome, thanks! Looks like the flashing is fixed, but now when I set Analog->Note it makes a sound (both on the press AND release, which I think is normal as it's expecting an analog input), but Analog->Button then Button->Note there is no input being received.

Same MIDI ID (I set to 36 usually, then test with a stock drumkit in Ableton, 36 is usually the default kick sound).

[paradajz]

I don't understand the reproduce scenario, and besides, this is no longer relevant to this thread. Please open either a new discussion or an issue.