StepFish is a stepper motor controller for the fischertechnik construction toy system based on an ATmega328 microprocessor. It can be used as a standalone controller (and I2C master) or as an I2C slave. Hardware features:
- up to four steppers driven by StepStick/Pololu or compatible carrier boards (e.g. A4988), connected via pin headers. Make sure to limit the carrier boards' current (see below).
- fischertechnik compatible connectors for two active low endstops per stepper axis
- three PWM pins for custom uses like servos, LEDs, or interrupt pins in I2C slave mode
- I2C connector compatible with the ftDuino and fischertechnik TX controllers.
- serial connector for programming or monitoring the ATmega328 with this kind of USB-serial/TTL/FTDI adapter
- fischertechnik compatible connectors for 5V in (chip logic) and stepper motor power. A DC-DC step-down 5V converter like this one can be added to the enclosure internally if you want to power the controller from the motor pins only.
- print-in-place reset button
- Two status LEDs for 5V (on) and stepper motor power.
The ZIP-file contains fritzing, gerber and PDF files for producing the one-sided PCB, which uses my printed flush sleeve design ("Printbuchse") for the fischertechnik typical 2.6mm jacks. Soldering is a bit tricky, as the connector pins are placed at the bottom of the PCB. If you are interested in building one yourself, please message me, or leave a comment, and I will provide details.
Warning: Make sure to limit your carrier boards' current as described e.g. here or here or here. My enclosure provides access to the carrier boards' potentiometers from the bottom, use an alligator clip attached to your screwdriver and one of the GND-pins for measurement.
At the moment, StepFish can only be used as a standalone controller, or with your own I2C-firmware, as the StepFish firmware is still under development. StepFish firmware will be based on the AccelStepper library, basically offering an I2C-wrapper to provide AccelStepper functionality over I2C, with additional endstop configuration and optional servo/interrupt functionality.
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Find my other fischertechnik designs here.