Arduino-based converter that lets unipolar steppers (e.g. 28BYJ-48 w/ ULN2003A) pretend to be bipolar steppers for things like GRBL or Marlin. Built to work with any Arduino-compatible atmega168/atmega328 board (ex: Arduino Uno or Adafruit Pro Trinket). Also includes schematic for a custom carrier board that makes connecting the steppers a snap!
Provides interface pins that work the same as the EasyDriver or DRV8825/A4988 StepStick and can be directly connected to a micro-controller running GRBL using the standard wiring.
Up to 3 steppers can be driven from one atmega328. Can be 5V or 12v, because the original driver (e.g. ULN2003A) is still used.
The code is easily portable to other AVRs. Requires compatibility with the PinChangeInterrupt library and the Stepper class included with the Arduino IDE. Also requires that the micro-controller have at least 6 digital pins available for each stepper (2-in, 4-out).
Will automatically power-down steppers after they have been idle for a period of time. Does not yet support the SLEEP or ENABLE pins, but the RESET pin can be used to a similar same effect.
Does not support micro-stepping, but may in the future.
Download the code as a zip file
or clone the repository. Open stepper_faker.ino in the Arduino IDE (version
1.6.x or higher, please) and send it to your device.
General wiring requirement: connect the ground from your controller running Stepper-Faker to the ground on the primary micro-controller running your grbl/marlin/etc software.
If your primary controller has enough power to run your Stepper-Faker board and all the steppers and your steppers are 5v, feel free to use that; otherwise you will need to power those separately using the appropriate power source.
Connect the "IN1/2/3/4" pins for each Stepper (A, B, or C) to the IN1/2/3/4 pins on the included ULN2003A driver board. Remember that Stepper-Faker already reverses the IN2 and IN3 pins, so you don't need to.
If your Stepper-Faker controller has enough power for all your steppers and they are 5v, feel free to use that; otherwise you will need to power those separately using the appropriate power source.
Follow the same wiring directions as with EasyDriver.
Leave SLP, ENABLE, and RESET un-connected. Connect the the appropriate STEP and DIR pins on your Stepper-Faker controller to the correct pins on your primary controller running your software.
Leave SLEEP and RESET un-connected. Connect the the appropriate STEP and DIR pins on your Stepper-Faker controller to the correct pins on your primary controller running your software.
Jan 13, 2016 - Add readme, update pins.
Jan 12, 2016 - Initial Commit
In no particular order.
- Remove BREADBOARDED_328 references in code.
- Set IN2/IN3 swapping with a #define.
- Set STEP and DIR pull-up or -down with #define.
- Set STEP and DIR high/low behaviour with a #define.
- Separate sleep timers per stepper.
- Ability to disable sleep timer.
- Add custom board files.
- Add Fritzing wiring diagrams.
- Conditionally [en/dis]able Serial, allow those pins to be used as SLEEP and ENABLE.
- Include support for MiniCore, allow xtal pins to be used as SLEEP and ENABLE.
- PWM-based micro-stepping? Is it even worth it?
- Test with atmega32u4 for Arduino Micro/Leonardo.
- Test with attiny84.
- Test with attiny4313.
- Test with attiny1634.
- Support attiny85? Not enough pins. Analog hack on RESET, or share STEP/DIR using analogRead? Can't use interrupts then.
GNU GPLv3
Source code: https://github.com/xunker/stepper_faker
(C) 2017 Matthew Nielsen, xunker@pyxidis.org