Alternate sample code for FIT0441
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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);
}