Blog 19

2 Wheeled car: Arduino Version

#define Motor 0x48

#include <Wire.h> 

//Time to pause rotating
//static unsigned long Pause = 10000;
static unsigned long Speed = 40;

void setup()
{
  Wire.begin(); // wake up I2C bus
  Serial.begin(9600);
}

byte get_var(byte address, byte reg)
{
  byte value;   
  Wire.beginTransmission(address);  
  Wire.write(reg);
  Wire.endTransmission(); 
  delayMicroseconds (10);
  Wire.requestFrom(Motor, 1);
  value = Wire.read();
  return value;
} 

void set_var(byte address, byte reg, byte value)
{
  Wire.beginTransmission(address); // transmit to motor     
  Wire.write(reg);
  Wire.write(value);   
  Wire.endTransmission();    // stop transmitting
} 

void loop()
{
  unsigned long AddressA;
  unsigned long AddressB;  

  char buf[32];
  set_var(0x48, 0x21, Speed); 
  set_var(0x48, 0x31, Speed);  

  AddressA = get_var(0x48, 0x21);
  sprintf (buf, "Speed:  A:%d ", AddressA);
  Serial.write (buf); 

  AddressB = get_var(0x48, 0x31);
  sprintf (buf, " B:  %d\r\n", AddressB);
  Serial.write (buf); 
 
 delay(500);

//  delay(Pause);
}

This is the list I have made for the Raspberry Pi Version, what also counts for the Arduino version(If your car is switched to the other side this can of course be the opposite):

• # X is forwards - Y is backwards
• #Wheels at front
• #20 A backwards
• #21 A forwards
• #22 A stop
• #30 B backwards
• #31 B forwards
• #32 B stop

You can also check the motor protocol, for more info.

In my example script we go forward with 0x21 + 0x31 having the same value. For other movements you should have(If you car is flipped this can of course be the opposite!):

To go backwards:

  set_var(0x48, 0x20, Same Speed value); 
  set_var(0x48, 0x30, Same Speed value); 

To go left:

  set_var(0x48, 0x21, High Speed value); 
  set_var(0x48, 0x31, Low Speed value); 

To go right:

  set_var(0x48, 0x21, Low Speed value); 
  set_var(0x48, 0x31, High Speed value); 

To stop the car:

  set_var(0x48, 0x21, Speed value doesn't matter); 
  set_var(0x48, 0x31, Speed value doesn't matter);

To rotate to the left:

  set_var(0x48, 0x21, Same Speed value); 
  set_var(0x48, 0x30, Same Speed value); 

To rotate to the right:

  set_var(0x48, 0x20, Same Speed value); 
  set_var(0x48, 0x31, Same Speed value);