Bajdi electronics

Dagu Rover 5

I’ve dusted of my Dagu Rover 5 🙂 While I’ve had my Rover 5 for almost 2 years I’ve never really used the encoders. Unfortunately my Rover 5 was delivered with an encoder that didn’t work right. So I decided to have a look at it and try to fix it. It turned out to be an easy fix. I just needed to adjust the potentiometer on the encoder control board. So now I had 4 working encoders 🙂

I’m using the Dagu 4 channel motor controller and a Dagu Red Back Spider controller on my Rover 5. The Rover 5 is fitted with 4 quadrature encoders. The 4 channel motor controller has 4 mixing circuits for the encoders. The mixing circuit takes the 2 inputs from the quadrature encoder and mixes them into a single output. So I needed to connect the 4 outputs of the mixing circuits to my Red Back Spider. The Red Back spider is based on the ATmega1280 micro controller (Arduino Mega) which has 6 external interrupts. I used interrupt 0 (pin D2), interrupt 1 (pin D3), interrupt 4 (pin D19) and interrupt 5 (pin D18). Interrupt 2 and 3 are also the I2C pins, I’m already using them for my digital compass.

I started with the same code as I had written for my other robot and changed it for 4 motors.
Next step is to integrate this code in my “Rover 5 remote control sketch”.

// http://www.bajdi.com
// Rover 5: 4 motors / 4 encoders
// Encoder speed control
// µController = ATmega1280

volatile unsigned long PulseM[4];   // Time between pulses
volatile unsigned long TimeM[4];  // Time when the last pulse got in
unsigned long lastPulseM[4] = {10000,10000,10000,10000};  // Time since the last pulse 
const int targetPulse =  8500;  // THIS INTEGER CONTROLS THE SPEED OF THE MOTORS (900 fastest - 8500 slowest)

const int DirM[4] = {
  30,31,32,33}; // direction pins 
const int PWMpinM[4] = {
  4,5,6,7};  // pwm pins
int PWMM[4];  // pwm settings

#define runEvery(t) for (static typeof(t) _lasttime;(typeof(t))((typeof(t))millis() - _lasttime) > (t);_lasttime += (t))

void setup()
{
  Serial.begin(115200);
  //Setup motor pins
  for(int i=0; i<4; i++)
  {
    pinMode(DirM[i], OUTPUT); 
  }
  for(int i=0; i<4; i++)
  {
    pinMode(PWMpinM[i], OUTPUT); 
  }
  // Setup encoder pins
  attachInterrupt(0,M1encoder,CHANGE);   // pin D2
  attachInterrupt(1,M2encoder,CHANGE);   // pin D3
  attachInterrupt(4,M3encoder,CHANGE);   // pin D19
  attachInterrupt(5,M4encoder,CHANGE);   // pin D18
}

void loop(void)
{
  for (int i=0; i<4; i+=1)
  {
    lastPulseM[i] = micros() - TimeM[i];
    if (lastPulseM[i] > targetPulse)
    {
      PWMM[i]+=1;
      if(PWMM[i] > 200)                   // Max pwm speed = 200
      {
        PWMM[i] = 200;
      }
    }
    if (lastPulseM[i] < targetPulse)
    {
      PWMM[i]-=1;
      if (PWMM[i] < 0)
      {
        PWMM[i] = 0;
      }
    }
    digitalWrite(DirM[i], HIGH);
    analogWrite(PWMpinM[i], PWMM[i]);
  }

  // serial printing
  runEvery(500){
    for (int i=0; i<4; i +=1)
    {
      Serial.print("PulseM = ");
      Serial.println(PulseM[i]);
    }
    for (int i=0; i<4; i +=1)
    {
      Serial.print("PWMM = ");
      Serial.println(PWMM[i]);
    }
  }
}

void M1encoder()
{
  PulseM[0]=micros()-TimeM[0];              // time between last state change and this state change
  TimeM[0]=micros();                        // update TimeM[0] with time of most recent state change
}

void M2encoder()
{
  PulseM[1]=micros()-TimeM[1];                               
  TimeM[1]=micros();                                      
}

void M3encoder()
{
  PulseM[2]=micros()-TimeM[2];                              
  TimeM[2]=micros();                                   
}

void M4encoder()
{
  PulseM[3]=micros()-TimeM[3];                            
  TimeM[3]=micros();
}