Test BOE Shield Arlo Encoder Connections

Test Encoder Connections

The Arlo has built-in encoders that can count how far the Arlo travels in terms of 144ths of a wheel revolution.  Although it’s not needed to run BOE Shield-Bot code, it’s best to make sure they are functioning correctly in case you want to improve the accuracy of the Arlo’s maneuvers later.  The next sketch will display the status of your encoder connections in the Terminal.  If there is a problem, it may indicate that the encoder cables have been swapped or that there is some other wiring problem.  Here are examples of what you might see:

  • We want the wheels to be able to spin freely during this test, so your Arlo on a box, stands, or some other stable platform that prevents its wheels from coming into contact with the table top.  
  • Upload Test Encoder Connections.ino.
  • Check the Terminal’s messages.  It’ll either tell you that the Arlo is ready for the next step, or describe the error it encountered and suggest either a fix, or at least where to look for a potential problem.

This sketch tests to make sure the Arlo's wheel encoder connections
are correct.  The Arlo will not be ready for the next step until you
have verified that the number of encoder transitions (ticks) for both
wheels are positive when the wheels roll forward.

If you have not already completed Test Arlo Motor Connections.c,
complete it first, then continue from here.

Use the Arduino IDE’s Upload button to run this sketch.  If the
Terminal displays the "Encoder connections are correct!..."
message, your Arlo is ready for the next step, which is running
navigation sketches.  

If the Terminal instead displays one or more "ERROR..."
messages, those encoder encoder connections will need to be
corrected.  For example, if the messages says, "ERROR: Motor 1
encoder connections are reversed!", you will need to unplug and
swap the two 3-wire encoder cables next to the Motor 1 terminal
on the DHB-10, swap them, and plug them back in.

Make sure to test between each adjustment.  Your arlo will not be
ready for the next step until you get the success message from
this test.

#include <ArloRobot.h>                     // Include Arlo library
#include <SoftwareSerial.h>                   // Include SoftwareSerial library

// Arlo and serial objects required
ArloRobot Arlo;                            // Arlo object
SoftwareSerial ArloSerial(12, 13);            // Serial in I/O 12, out I/O 13

int countsLeft, countsRight;                  // Encoder counting variables
void setup()                                  // Setup function
tone(4, 3000, 2000);                        // Piezospeaker beep
Serial.begin(9600);                         // Start terminal serial port

 ArloSerial.begin(19200);                    // Start DHB-10 serial com
Arlo.begin(ArloSerial);                     // Pass to Arlo object

 Serial.println("Testing...");               // Display testing message

 Arlo.clearCounts();                         // Clear encoder counts

 Arlo.writeMotorPower(32, 32);               // Go forward very slowly
delay(4000);                                //   for three seconds
Arlo.writeMotorPower(0, 0);                 //   then stop

 countsLeft = Arlo.readCountsLeft();         // Get left & right encoder counts
countsRight = Arlo.readCountsRight();

 Serial.print("countsLeft = ");              // Display encoder measurements
Serial.print(countsLeft, DEC);
Serial.print(", countsRight = ");
Serial.println(countsRight, DEC);

 // Both distances positive?   
if((countsLeft > 175) && (countsLeft < 325)
&& (countsRight > 175) && (countsRight < 325))
   // Success message
   Serial.println("Encoder connections are correct!");
   Serial.println("Your Arlo is ready for the next step.");
   // Left encoders cables correct? 
   if(countsLeft > 175 && countsLeft < 325)    
     // Correct encoder message
     Serial.println("Motor 1 encoder cables are connected");
     Serial.println(" correctly.");
   // Left encoders cables swapped?
   else if(countsLeft > -325 && countsLeft < -125)  
     // Swapped encoder message
     Serial.println("ERROR: Motor 1 encoder connections");
     Serial.println(" are reversed!");
   else                                      // Other problem
     // Other encoder error message
     Serial.println("ERROR: Motor 1 encoder values out of ");
     Serial.println("range. Recheck encoder connections ");
     Serial.println("and assemblies.");
   // Right encoders cables correct?     
   if(countsRight > 175 && countsRight < 325)
     // Correct encoder message
     Serial.println("Motor 2 encoder cables are ");
     Serial.println("connected correctly.");
   // Right encoders cables swapped?  
   else if(countsRight > -325 && countsRight < -125)
     // Swapped encoder message
     Serial.println("ERROR: Motor 2 encoder connections ");
     Serial.println("are reversed!");
   else                                      // Other problem
     // Other encoder error message
     Serial.println("ERROR: Motor 2 encoder values ");
     Serial.println("out of range. Recheck encoder ");
     Serial.println("connections and assemblies.");

 Arlo.writePulseMode();                      // Get ready for pulse control

 Serial.print("Test done.\n\n");             // Display status

void loop() {}                                // Nothing for main loop