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HomeSpan/docs/StepperDrivers/Stepper_A3967.md

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Stepper_A3967

This is a derived class of StepperControl designed to operate stepper motors driven by an Allegro A3967 chip.

The Allegro A3967 is a specialized driver designed for stepper motors. It contains a built-in PWM generator and pre-programmed stepping modes. Wiring for the Sparkfun EasyDriver Stepper Motor Board that uses this chip is as follows:

Power Connections

  • GND - connect to GND on the ESP32, and to ground of external DC power supply
  • M+ - connect to external DC power supply that will drive stepper motor. An on-board regulator also uses this supply to provide VCC to the rest of the board. For use with an ESP32, you must short the 3.3V/5V jumper with a blob of solder to select 3.3V

Motor Connections

  • Motor A - connect to the "A" coil of the stepper motor
  • Motor B - connect to the "B" coil of the stepper motor

Control Connections

  • MS1, MS2 - connect to two digital pins on the ESP32 - used to set the step type mode
  • STEP, DIR - connect to two digital pins on the ESP32 - used to step the motor and set the direction
  • ENABLE - connect to a digital pin on the ESP32 - used to enable/disable to motor driver
  • SLEEP, RESET - already pulled high on the EasyDriver board, so no connection neeed. If using a different driver board, ensure these pins are pulled high, else connect to VCC
  • PFD - not used

The Stepper_A3967 class includes the following constructor:

  • Stepper_A3967(int MS1, int MS2, int STEP, int DIR, int ENABLE)

    • controls the driver board using 5 digital pins from the ESP32, where the parameters specify the pin numbers. Supports the following step type modes:

      • FULL_STEP_TWO_PHASE
      • HALF_STEP
      • QUARTER_STEP
      • EIGHTH_STEP

❗Note: The A3967 chip does not support a short brake state. Calls to the brake() method, as well as setting the endAction parameter in the move() and moveTo() methods to StepperControl::BRAKE have no effect on the motor driver.

↩️ Back to the Stepper Motor Control page