Encoders¶

The encoders detect how much the wheels have turned. We can use this information to figure out how far the robot has driven.

• Encoders
• Sample code
• Header File
• Debugging
• Schematic

Sample code¶

#include <dragonfly_lib.h>
#include <encoders.h>
/*
 * Drives the robot forward for 1500 encoder distance units
 */
void encoders_sample(void)
{
  encoders_init(); // must be called before using any encoder code
  motors_init(); // must be called before using any motors code

  motor_l_set(FORWARD, 500); // turn on the left motor
  motor_r_set(FORWARD, 500); // turn on the right motor

  int distance = 0; // initialize distance variable
  while(distance < 1500) // while we have traveled less than 1500 distance units, do the following:
  {      
    distance = encoder_get_x(LEFT); // get the newest encoder value from the left encoder
                                    // the right encoder value should be about the same since we are driving straight
  }
  // we won't get out of the while loop until we have traveled 1500 distance units
  // since we got here, we have driven far enough
  motors_off(); // stop the motors
}

Header File¶

For a full list of functions, see the encoders code header file.

Debugging¶

Things to check/maintain:

• Check battery
• wheel slop (make sure wheels are not loose)
• encoder board should have 2mm spacing (2 #4 lock washers)
• check wiring on the underside. The wires have gotten pulled out from replacing batteries.

Schematic¶

NOTE: stuff has to be wired up on the board to work. This has something to do with the chip select pins. See some of the robots to get this working