Pololu Trex jr + Arduino interface +DC motor

Hi, I've newly got my first Arduino and I already did some basic LED projects.
Now I would like to control a DC Motor (Igarashi 20G-150) and for that i decided to use the motor controller Pololu Trex jr coupled to the Arduino 2009.
The main goal of this small Projekt is to build a sun tracking system.

The tasks are quite simple:
The difference between to two photodiodes determines if the DC motor rotates full speed to the left or to the right.

I have already made a simplified sketch with two LEDs simulating the motor direction using simply the Arduino and it works properly.

//Project SUN Tracking1
//Pin assignment
int GreenPin=10;
int RedPin=11;

int PD1Pin=0;
int PD2Pin=1;

//Variable declaration
int DifValue=0;
int PD1Value=0;
int PD2Value=0;
int Range=15;

void setup(){
  Serial.begin(9600);
  Serial.flush();
  pinMode(GreenPin, OUTPUT);
  pinMode(RedPin, OUTPUT);
}
void loop(){
  // Read and display Phododiode Values
  PD1Value = analogRead(PD1Pin);
  Serial.print("PD1 Value: ");
  Serial.println(PD1Value);
  
  PD2Value = analogRead(PD2Pin);
  Serial.print("PD2 Value: ");
  Serial.println(PD2Value);
  
  // Difference value between Photodiodes
  DifValue = PD1Value-PD2Value;
  Serial.print("Dif Value: ");
  Serial.println(DifValue);
  
  // Decison Logic 
  if(DifValue < -Range ) {
    digitalWrite(GreenPin,LOW);
    digitalWrite(RedPin,HIGH);
    Serial.print(" ");
  }
  if(DifValue > Range ) {    
    digitalWrite(RedPin,LOW);
    digitalWrite(GreenPin,HIGH);
   Serial.print(" "); 
  }
  if(DifValue >= -Range && DifValue <= Range) {
    digitalWrite(RedPin,LOW);
    digitalWrite(GreenPin,LOW);
    Serial.print("Maximum intensity ");
  }
  
  delay(1000);
}

Now my questions reside in:

  • the code for Serial interface code between the Arduino and the Trex jr

  • the code with specific commands to send to TRex jr

  • Rotate Motor 1 to the Left

  • Rotate Motor 1 to the Right

  • The Trex jr jumper settings for this case

I would be very thankfulif someone could provide me an example for this configuration.

I know that for this purpose i could simple use a H-Bridge connected to the Arduino, but this way (with the Trex jr) i can learn the basics of Serial communication.

Thanks in advance for you help!

See ya...

Tom D

This link Pololu TReX Jr Dual Motor Controller DMC02 has a C# application that can send serial data to the Trex Jr. It has other documents that describe the commands to send to make things happen. These should answer all of your questions.