My attempt to make it work: EncPlex74165/MPX_74165 with Teensy 4.1

[weitlos]

Hello Luni,

first of all thank you so much for this detailed project! It was actually the inspiration for me to get started with MicroControllers and I am working now on my first project. My overall aim is to build a custom MidiController to control FL Studio. This also involves a set of rotary encoders that I would like to use for that.

Unfortunately I encounter a problem with the MPX_74165 board that I want to use. I tried to summarize my issue in this discussion and hope it is the right place to adress this topic. :)

Aim:
I would like to use 2 daisy chained MPX_74165 boards to connect 16 rotary encoder with my Teensy 4.1. (Currently I only work with one board for the PoC).

Problem:
When rotating the encoder no value change is registered.

Observations:
Without the 3 long bus resistors (I assume based on the Schematics that it is for the pull-down?) there is input registered by the Teensy however it is random and probably due to the interferences at the wires.

Adding the resistors will lead to no input registration at all. Nothing does happen when I rotate the encoder.

Tests:
I tested the encoder with the Single Polled Encoder from your library and it works perfectly there. Therefore I assume that it is no mechanical issue.

I also checked the connectivity of all parts and did a check of the soldering and the electrical paths working correctly.

I tried all CountModes.

Setup:
Teensy 4.1 connected via USB to PC.
Pins:
QH_A = 10
QH_B = 11
pinLD = 2
pinCLK = 7
VCC = 3,3V

QH_S unused! (This is the kable not plugged in you might see on the pictures.

Code:

#include "EncoderTool.h"
#include <Encoder.h>
#include "Arduino.h"

constexpr size_t bufSize = 10;

Encoder encoderA(30, 31);
EncoderTool::PolledEncoder encoderB;

constexpr unsigned encoderCount = 2; // number of attached  (daisy chain shift regesters for more than 8)

constexpr unsigned QH_A = 10;   // output pin QH of shift register B
constexpr unsigned QH_B = 11;   // output pin QH of shift register A
constexpr unsigned pinLD = 2;  // load pin for all shift registers)
constexpr unsigned pinCLK = 7; // clock pin for all shift registers
                               // 74165 datasheet: http://www.ti.com/product/SN74HC165

EncoderTool::EncPlex74165 encoders(encoderCount, pinLD, pinCLK, QH_A, QH_B);

void onAnyEncoder(uint8_t channel, int value, int delta)
{
  Serial.print("Encoder: ");
  Serial.print(channel);
  Serial.print(" value: ");
  Serial.print(value);
  Serial.print(" delta: ");
  Serial.print(delta);
  Serial.println();
}

void onFirstEncoder(int value, int delta)
{
  Serial.print("Encoder 0 (standalone callback): ");
  Serial.println();
}

void setup()
{
  Serial.begin(115200);
  Serial.setTimeout(1);

  encoderB.begin(28, 29);
  encoderB.setCountMode(EncoderTool::CountMode::full);

  encoders.begin(EncoderTool::CountMode::halfAlt);
  encoders[0].attachCallback(onFirstEncoder);
  encoders.attachCallback(onAnyEncoder);

  Serial.println("Setup complete");
}

const unsigned long eventInterval = 1000;

void loop()
{
  encoderB.tick();
  encoders.tick();

  unsigned long currentTime = millis();
  static unsigned long uiLastRefresh = millis();
  if (currentTime - uiLastRefresh >= eventInterval)
  {

    uiLastRefresh = currentTime;
    Serial.println("Alive!");

    /*int valueA = encoderA.read();
    Serial.print("EncoderA value: ");
    Serial.println(valueA);

    int valueB = encoderB.getValue();
    Serial.print("EncoderB value: ");
    Serial.println(valueB);*/

    /*for (unsigned i = 0; i < encoderCount; i++)
    {
      if (encoders[i].valueChanged())
      {
        Serial.print("Encoder:");
        Serial.print(i);
        Serial.print(" value:");
        Serial.println(encoders[i].getValue());
      }
      else
      {
        Serial.print("Encoder:");
        Serial.print(i);
        Serial.println(" unchanged.");
      }
    }*/
  }
}

Parts (BOM):

Product ID	Description	Source
	Your MPX_74165 PCB	Aisler
SIL 9-8 4,7K	Widerstandsnetzwerk, 8 x 4,7 KOhm, 2%, SIL-9	Reichelt
74HC 165	Shift Register, 8-Bit, 2 ... 6 V, DIL-16	Reichelt
METALL 4,70K	Widerstand, Metallschicht, 4,70 kOhm, 0207, 0,6 W, 1%	Reichelt
C3X7R 100NA50	Vielschicht-Kerko, 100nF, 50V, 125°C	Reichelt
TEENSY 4.1	Teensy 4.1, USB, ohne Header	Reichelt
STEC12E07	Drehimpulsegeber, 24 Impulse / 24 Rastungen, vertikal	Reichelt

Ideas:
Could it be that the resistors are to weak or strong and therefore not letting any signal through?

Could there be a specific configuration of the Pins required when this Multiplexer is used with Teensy 4.1?

Final words:
Any help is highly appreciated I really hope that there is a way to make it work! :)
I hope the information I provided does help in any way to give you an overview about the setup.

All the best to you!

Greetings from Berlin,
weitlos