I've just been getting a FIT0441 running on a Nano, and found the sample on the Wiki was not as helpful as it could be. Here's my current code in case it's useful.

#define DIRECTION_PIN 10

#define PWM_PIN 11

#define ENCODER_PIN 2 // must be an interrupt-capable pin, 2 is a good choice on a Nano

long pulsesPerRev = 45*6; // gearbox is 45:1 reduction, motor has 6 pulses/rev

unsigned long directionChangeTime = 0;

bool direction = HIGH;

int rpmTarget = 100;

int encoderPulses = 0;

long lastEncoderTime = 0;

long encoderInterval = 1;

long encoderRPM = 0;

long lastPrintMillis = 0;

void setup() {

// put your setup code here, to run once:

Serial.begin(115200);

TCCR2B = TCCR2B & 0b11111000 | 1; //set PWM frequency to 32khz, good for Nano and Uno

pinMode(DIRECTION_PIN, OUTPUT); //direction control PIN 10 with direction wire

pinMode(PWM_PIN, OUTPUT);

digitalWrite(DIRECTION_PIN, direction);

attachInterrupt(digitalPinToInterrupt(ENCODER_PIN), encoderISR, RISING ) ;

}

void loop() {

if (millis() - directionChangeTime > 5000) {

direction = !direction;

digitalWrite(DIRECTION_PIN, direction);

directionChangeTime = millis();

}

if (Serial.available()) {

int a = Serial.parseInt();

if( a != 0 )

{

rpmTarget = 255 - a;

analogWrite(PWM_PIN, rpmTarget ); //input speed (must be int)

delay(200);

}

}

long now = millis();

if( now-lastPrintMillis > 500 )

{

Serial.print(" r/min, target is ");

Serial.println(rpmTarget);

Serial.print("Encoder interval ");

Serial.println(encoderInterval);

Serial.print("encoderPulses ");

Serial.println(encoderPulses);

Serial.print("totalRevs ");

Serial.println(encoderPulses/pulsesPerRev);

Serial.print("encoderRPM ");

Serial.println(encoderRPM);

lastPrintMillis = now;

}

i = 0;

}

void encoderISR()

{

if( direction )

encoderPulses ++;

else

encoderPulses--;

long now = micros();

encoderInterval = now - lastEncoderTime;

lastEncoderTime = now;

encoderRPM = (60L * 1000000L) / (encoderInterval * pulsesPerRev);

}