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Thread: Stepper Won't Reverse, Instead Cooks Eggs

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  1. #1
    Junior Member
    Join Date
    Jan 2021

    Stepper Won't Reverse, Instead Cooks Eggs

    Sorry if this a repeat question. I spent a good portion of the last couple evenings trying to figure out what I'm doing wrong, searching thither and yon.

    Virtually all of the hits on Google refer to specific issues with CNC controller kits, voltage being too low, or programming errors.

    Background: I'm the Jon Snow of electronics
    More background: I have what I believe to be a fairly simple setup:

    1. Small stepper motor (,
    2. 3.3V to 5V Level Shifter
    3. Teensy 3.5
    4. Digital Stepper Driver (,
    5. 24V x 15A Power Supply

    Code and schematic follow. I'm a programmer but I am very new to electronics. I learned KiCAD just to make this post so I didn't waste anyone's time if possible. The issue is as follows:

    1. The code runs and happily rotates the motor in one direction.
    2. When the code flips to reverse direction, it instead stands still.
    3. It happily rotates/stands still until it makes a buzzing noise and gets hot (this is the point I gave up and started learning KiCAD).

    Validation Steps:
    1. Checked and re-checked the Red, Green, Blue, Black wires to A+/-, B+/- until my eyes crossed
    2. Validated that the code only sends the reverse signal once per second (during inversion).
    3. Put a multimeter on the level shifter to validate that the output for PUL and DIR is changing from 200mV to 4.8V in time with the serial output of the code.

      Stepper Motor Test
      Uses MA860H or similar Stepper Driver Unit
      Has speed control & reverse switch
      DroneBot Workshop 2019
    // Defin pins
    int driverPUL = 7;    // PUL- pin
    int driverDIR = 6;    // DIR- pin
    int ledPin = 13;
    // Variables
    int pd = 500;       // Pulse Delay period
    boolean setdir = HIGH; // Set Direction
    int reverse = 0;
    // Interrupt Handler
    void setup() {
      pinMode (driverPUL, OUTPUT);
      pinMode (driverDIR, OUTPUT);
      pinMode (ledPin, OUTPUT);
      digitalWrite(driverDIR, setdir);
      digitalWrite(ledPin, HIGH);
      delayMicroseconds(1 * 1000000);
      Serial.println("Validate LED");
      delayMicroseconds(1 * 1000000);
      digitalWrite(ledPin, LOW);
      delayMicroseconds(1 * 1000000);
      digitalWrite(ledPin, HIGH);
    void loop() {
      if (reverse >= 1000) {
        Serial.printf("Reverse loop: %d to %d\n", reverse, setdir);
        setdir = (setdir == LOW) ? HIGH : LOW;
        digitalWrite(driverDIR, setdir);
        digitalWrite(ledPin, setdir);
        reverse = 0;
      digitalWrite(driverPUL, HIGH);
      digitalWrite(driverPUL, LOW);
    "Schematic" to follow. I screwed up the drawing. Not pictured is the Neutral wire on the power supply connected to Neutral on the digital stepper driver. I'm tired and I just can't go back and open up the library definition and rewire the drawing.

    Thank you for any advice or help.

    EDIT: I screwed up the drawing. Uploading another one in just a moment.
    Attached Files Attached Files

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