First version

corrected motor pin assignement
rewrote turn and move application to speed.
Will try other version with turn being proportionnal to move

CG_MarioKart.ino

@@ -13,15 +13,15 @@ const int ch2_pin = 11 ;
 
 int ch1; // Here's where we'll keep our channel values
 int ch2;
-int ch3;
 
 int move; // Forward/Back speed
 int turn; // Turning Factor
-
-int pwm_a = 4;  //PWM control for motor outputs
-int pwm_b = 7;  //PWM control for motor outputs
-int dir_a = 5;  //direction control for motor outputs
-int dir_b = 6;  //direction control for motor outputs
+int speeds_pin[2] = {5, 6};
+int dirs_pin[2] = {4, 7};
+//int pwm_a = 5;  //PWM control for motor outputs
+//int pwm_b = 6;  //PWM control for motor outputs
+//int dir_a = 4;  //direction control for motor outputs
+//int dir_b = 7;  //direction control for motor outputs
 
 int threshold = 30 ;
 
@@ -40,45 +40,61 @@ pinMode(ch2_pin, INPUT);
 
 Serial.begin(9600); // Pour a bowl of Serial (for debugging)
 
-  pinMode(pwm_a, OUTPUT);  //Set control pins to be outputs
-  pinMode(pwm_b, OUTPUT);
-  pinMode(dir_a, OUTPUT);
-  pinMode(dir_b, OUTPUT);
-
-  analogWrite(pwm_a, 0);  
-  analogWrite(pwm_b, 0);
+  for(int i; i<2; i++){
+    pinMode(speeds_pin[i], OUTPUT);
+    pinMode(dirs_pin[i], OUTPUT);
+    analogWrite(speeds_pin[i], 0) ;
+  }
+//  pinMode(pwm_a, OUTPUT);  //Set control pins to be outputs
+//  pinMode(pwm_b, OUTPUT);
+//  pinMode(dir_a, OUTPUT);
+//  pinMode(dir_b, OUTPUT);
+
+//  analogWrite(pwm_a, 0);  
+//  analogWrite(pwm_b, 0);
 }
 
 
 void loop() {
-  
+
+  //Read RC values and give wide center point
   ch1 = pulseIn(ch1_pin, HIGH, 25000); // Read the pulse width of  
   ch2 = pulseIn(ch2_pin, HIGH, 25000); // each channel
-
   ch1 = middleThreshold(ch1, threshold);
   ch2 = middleThreshold(ch2, threshold);
   
-
+  //Refresh and scale raw move values
   move = map(ch2, 1000,2000, -255, 255); //center over zero
   move = constrain(move, -255, 255); //only pass values whose absolutes are
                                    //valid pwm values
-
-  /*What we're doing here is determining whether we want to move
-  forward or backward*/
-  if(move>0){digitalWrite(dir_a, 1);digitalWrite(dir_b, 1);};
-  if(move<0){digitalWrite(dir_a, 0);digitalWrite(dir_b, 0); move=abs(move);};
-  
-  /*Here we're determining whether a left or a right turn is being 
-  executed*/
   turn = map(ch1,1000,2000,-255,255);
   turn = constrain(turn, -255, 255);
+
+  //calculate each motor speed
+  int speeds[2] = {0, 0} ;
+  int dirs[2] = {0, 0} ;
   
-  /*This is where we do some mixing, by subtracting our "turn" 
-  variable from the appropriate motor's speed we can execute
-  a turn in either direction*/
-  if(turn>=0){analogWrite(pwm_b, move-turn); analogWrite(pwm_a, move);};
-  if(turn<0){turn=abs(turn); analogWrite(pwm_a, move-turn); analogWrite(pwm_b, move);};
-  
+  if (turn>0) { speeds[0] = move; speeds[1] = move - turn; }
+  else {speeds[0] = move-turn; speeds[1] = move ;}
+
+  //apply to driver
+  for(int i =0; i<2; i++) {
+    dirs[i] = speeds[i] > 0 ? 1 : 0 ;
+    speeds[i] = abs( speeds[i]);
+    digitalWrite(dirs_pin[i], dirs[i]) ;
+    analogWrite(speeds_pin[i], speeds[i]) ;
+    
+  }
+
+//  analogWrite (
+// 
+//  
+//  /*This is where we do some mixing, by subtracting our "turn" 
+//  variable from the appropriate motor's speed we can execute
+//  a turn in either direction*/
+//  if(turn>=0){analogWrite(pwm_b, move-turn); analogWrite(pwm_a, move);};
+//  if(turn<0){turn=abs(turn); analogWrite(pwm_a, move-turn); analogWrite(pwm_b, move);};
+////  analogWrite(pwm_b, move); analogWrite(pwm_a, move);
   
   Serial.print("move:"); //Serial debugging stuff
   Serial.println(move);