Arduino + fischertechnik

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This week I blew the dust off my old fischertechnik Experimenta Computing kit to see about controlling it with Arduino. If I can control the kit with Arduino, I can get it to respond to the EPOC via OSC with Processing. More about that later.

The kit was made to interface with a PC via parallel port. It includes I/O for four motors/lamps/etc. (M1 – M4), eight binary switches (E1 – E8), and two analog inputs for pots, photo-resistors, etc. (EX, EY). The models on the base plate are powered through a distributing box that connects to the interface via a 20-pin IDC ribbon cable. Here is a pinout that I sorted out with a multimeter:

Obviously, Arduino has enough I/O to handle the kit’s variety — almost. The kit’s motors are powered by 6–9vdc, so I am using a Rugged Circuits motor driver shield and 9v battery to power two of them. The shield will not power four motors, but M3 and M4 can be connected to two of Arduino’s other PWM pins in order to power other components. Here is a sketch for a switch to turn the motor on when pressed:

#define M1 3 // motor output
#define M1_DIR 12 // direction output, not used in loop
#define E1 5 // binary input (push switch)

int toggle = 0;

void setup() {
  // configure all outputs off for now
  pinMode(M1, OUTPUT); digitalWrite(M1, LOW);
  pinMode(M1_DIR, OUTPUT); digitalWrite(M1_DIR, LOW);
  // configure input
  pinMode(E1, INPUT);
  
  analogWrite(M1, 0); // motor off for now
}

void loop() {
  if(digitalRead(E1) == HIGH) {
    toggle = 1;
  }
  while(toggle == 1) {
    analogWrite(M1, 255);
    if(digitalRead(E1) == LOW) {
    toggle = 0;
    }
  }
  analogWrite(M1, 0);
}

Since the motor shield has stackable headers, I am thinking about creating a shield for the remaining I/O, using a Technological Arts IDC ribbon cable to breadboard adapter and an Adafruit proto shield kit.

Cf. scratchfisch.org, a Scratch driver for fischertechnik kits.