Dagu Rover 5 from Bajdi on Vimeo.

// http://www.bajdi.com
// Dagu Rover 5 chassis with 4 motors
// Remote control through Nrf24L01 2,4GHz wireless module
// µcontroller = Dagu Red back spider, Arduino Mega 1280 compatible
// Motor controller = Dagu 4 channel motor controller
// Motor 1 and 2 on the left
// Motor 3 and 4 on the right

#include <SPI.h>
#include <Mirf.h>
#include <nRF24L01.h>
#include <MirfHardwareSpiDriver.h>

/* Nrf24L01 pinout
1 GND
2 VCC (3,3V)
3 CE    pin 48 on Mega 1280
4 CSN   pin 49 on Mega 1280
5 SCK   pin 52 on Mega 1280
6 MOSI  pin 51 on Mega 1280
7 MISO  pin 50 on Mega 1280
8 IRQ (not used)
*/

int DirM1 = 30; // direction motor 1
int DirM2 = 31; // direction motor 2
int DirM3 = 32; // direction motor 3
int DirM4 = 33; // direction motor 4
int PWMM1 = 3;  // pwm motor 1
int PWMM2 = 4;  // pwm motor 2
int PWMM3 = 5;  // pwm motor 3
int PWMM4 = 6;  // pwm motor 4

int fs; // forward speed
int bs; // backward speed
int ls; // turn left speed
int rs; // turn right speed

int joystick[3];    // Array with 2 analog values (X,Y-axis) and one digital (Z-axis) from transmitter/joystick

void setup() {

  pinMode(DirM1, OUTPUT);  // direction motor 1, left front
  pinMode(DirM2, OUTPUT);  // direction motor 2, left rear
  pinMode(DirM3, OUTPUT);  // direction motor 3, right front
  pinMode(DirM4, OUTPUT);  // direction motor 4, right rear
  pinMode(PWMM1, OUTPUT);  // PWM motor 1
  pinMode(PWMM2, OUTPUT);  // PWM motor 2
  pinMode(PWMM3, OUTPUT);  // PWM motor 3
  pinMode(PWMM4, OUTPUT);  // PWM motor 4
  Mirf.cePin = 48;             //ce pin
  Mirf.csnPin = 49;            //csn pin
  Mirf.spi = &MirfHardwareSpi;
  Mirf.init();
  Mirf.setRADDR((byte *)"serv1");
  Mirf.payload = sizeof(joystick);
  Mirf.config();
}

void loop() { 

  int X = joystick[0];    // joystick X-axis
  int Y = joystick[1];    // joystick Y-axis 

  while(!Mirf.dataReady()){
  }
  Mirf.getData((byte *) &joystick);

  if (X > 500 && X < 540 && Y > 490 && Y < 530 )    // joystick is centered
  {
    analogWrite(PWMM1, 0);
    analogWrite(PWMM2, 0);
    analogWrite(PWMM3, 0);
    analogWrite(PWMM4, 0);
  }

  if (X <= 500 && Y > 490 && Y < 530)               // joystick forward = all motors forward
  {
    fs = (map(X, 500, 0, 35, 255));
    digitalWrite(DirM1, HIGH);
    digitalWrite(DirM2, HIGH);
    digitalWrite(DirM3, HIGH);
    digitalWrite(DirM4, HIGH);
    analogWrite(PWMM1, fs);
    analogWrite(PWMM2, fs);
    analogWrite(PWMM3, fs);
    analogWrite(PWMM4, fs);
  }

  if (X >= 540 && Y > 490 && Y < 530)               // joystick backward = all motors backward
  {
    bs = (map(X, 540, 1023, 35, 255));
    digitalWrite(DirM1, LOW);
    digitalWrite(DirM2, LOW);
    digitalWrite(DirM3, LOW);
    digitalWrite(DirM4, LOW);
    analogWrite(PWMM1, bs);
    analogWrite(PWMM2, bs);
    analogWrite(PWMM3, bs);
    analogWrite(PWMM4, bs);
  }

  if (Y <= 490 && X > 500 && X < 540)              // joystick left = left motors backward && right motors forward
  {
    ls = (map(Y, 490, 0, 35, 255));
    digitalWrite(DirM1, LOW);
    digitalWrite(DirM2, LOW);
    digitalWrite(DirM3, HIGH);
    digitalWrite(DirM4, HIGH);
    analogWrite(PWMM1, ls);
    analogWrite(PWMM2, ls);
    analogWrite(PWMM3, ls);
    analogWrite(PWMM4, ls);
  }

  if (Y >= 530 && X > 500 && X < 540)              // joystick right = left motors forward && right motors backward
  {
    rs = (map(Y, 530, 1023, 35, 255));
    digitalWrite(DirM1, HIGH);
    digitalWrite(DirM2, HIGH);
    digitalWrite(DirM3, LOW);
    digitalWrite(DirM4, LOW);
    analogWrite(PWMM1, rs);
    analogWrite(PWMM2, rs);
    analogWrite(PWMM3, rs);
    analogWrite(PWMM4, rs);
  }
}

/*
 Blink without delay using a DS1307
 Led blinks once every second.
 */

#include <Wire.h>
const int DS1307_I2C_ADDRESS = 0x68;

const int led =  13;      // the number of the light pin
int ledState = LOW;
int lastTime = -1;
byte second, minute, hour;

// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val)
{
  return ( (val/16*10) + (val%16) );
}

void getDateDs1307()
{
  // Reset the register pointer
  Wire.beginTransmission(DS1307_I2C_ADDRESS);
  Wire.send(0x00);
  Wire.endTransmission();

  Wire.requestFrom(DS1307_I2C_ADDRESS, 1);

  second     = bcdToDec(Wire.receive() & 0x7f);
}

void setup() {
  Wire.begin();
  pinMode(led, OUTPUT);
}

void loop(){

  getDateDs1307();
  int time1 = second;
  if (abs(time1 - lastTime) > 1)
  {
    if (ledState == LOW)
      ledState = HIGH;
    else
      ledState = LOW;

    // set the LED with the ledState of the variable:
    digitalWrite(led, ledState);
    lastTime = time1;
  }
}

Arduino Uno on a breadboard

The Arduino Uno together with the Arduino IDE is an easy way to program the Atmel ATmega 328P micro controller. You don’t really need to buy an Arduino board if you want to play with the Arduino IDE. You can just buy an Atmel ATmega 328P, 2 capacitors, a crystal and a 10K resistor. Plug it on a breadboard and start playing. There is one issue though you need a way to put the sketch on the micro controller. The easiest method is to use an Arduino board if you already have one. Else you can buy an ISP programmer. The official Arduino website has instructions on how to accomplish this. I bought an Atmel ATmega 328P from the official Arduino store, it already had the Arduino Uno boot loader preprogrammed. Making it all a lot easier. I used these instructions to connect the 328P to my Uno. It did need to search for some things before I could connect it all. The website doesn’t have the pinout of the ATmega 328P, you can download the data-sheet from the Atmel website. The Arduino pin numbers are not the same as the ones Atmel uses in their data-sheet but I found that information here. To connect it all you only need 2 ceramic capacitors, a crystal and a 10K resistor. I had bought a set of ceramic capacitors from Arduino-direct some time ago. I didn’t know that the little numbers on them were not the value but capacitors codes. I found the information on how these translate to the value of the capacitor on this website.
After uploading the sketch I powered the ATmega 328P on the breadboard from my lab power supply through a L7805CV voltage regulator and it worked It’s all pretty straightforward, no special tricks are involved. So now I know it’s not that difficult to make my own Arduino board