Problem adding IR receiver to smart car

Question

I’m making a smart car using an arduino uno, sensor shield v5, motor control with a L298N and a servo motor + HC-SR04 ultrasound sensor. I want to add a IR receiver on the board so I can also control the car with a remote.

The problem is when I add in the code for the IR Receiver and make the 3 additional connections, the right motor doesn’t respond anymore, it only moves at the beginning, though slower than the left one during the initial setup, then only the left motor functions properly.

Here is the whole code with comments next to the IR-Receiver specific code:

#include <Servo.h>
#include <IRremote.h> //IR Receiver
Servo servo ;
const int trigPin = 13;
const int echoPin = 12;
const int servoPin = 11;
const int enAPin = 6;
const int in1Pin = 7;
const int in2Pin = 5;
const int in3Pin = 4;
const int in4Pin = 2;
const int enBPin = 3;
const int receiverPin = 9; //IR Receiver
IRrecv irrecv(receiverPin); //IR Receiver
decode_results signals; //IR Receiver
enum Motor { LEFT, RIGHT };
void go(enum Motor m, int speed)
{
 digitalWrite (m == LEFT ? in1Pin : in3Pin , speed > 0 ? HIGH : LOW );
 digitalWrite (m == LEFT ? in2Pin : in4Pin , speed <= 0 ? HIGH : LOW );
 analogWrite(m == LEFT ? enAPin : enBPin, speed < 0 ? -speed : speed );
}
void testMotors ()
{
 static int speed[8] = { 128, 255, 128, 0 , -128, -255, -128, 0};
 go(RIGHT, 0);
 for (unsigned char i = 0 ; i < 8 ; i++)
 go(LEFT, -speed[i]), delay(200);
 
 for (unsigned char i = 0 ; i < 8 ; i++)
 go(RIGHT, speed[i]), delay(200);
}
unsigned int readDistance()
{
 digitalWrite(trigPin, HIGH);
 delayMicroseconds(10);
 digitalWrite(trigPin, LOW);
 unsigned long period = pulseIn(echoPin, HIGH);
 return period * 343 / 2000;
}
#define NUM_ANGLES 7
unsigned char sensorAngle[NUM_ANGLES] = {60, 70, 80, 90, 100, 110, 120};
unsigned int distance [NUM_ANGLES];
void readNextDistance()
{
 static unsigned char angleIndex = 0;
 static signed char step = 1;
 distance[angleIndex] = readDistance();
 angleIndex += step ;
 if (angleIndex == NUM_ANGLES - 1) step = -1;
 else if (angleIndex == 0) step = 1;
 servo.write(sensorAngle[angleIndex]);
}
void setup () {
 Serial.begin(9600); //IR Receiver
 irrecv.enableIRIn(); //IR Receiver
 pinMode(trigPin , OUTPUT);
 pinMode(echoPin, INPUT);
 digitalWrite(trigPin, LOW);
 pinMode(enAPin, OUTPUT);
 pinMode(in1Pin, OUTPUT);
 pinMode(in2Pin, OUTPUT);
 pinMode(in3Pin, OUTPUT);
 pinMode(in4Pin, OUTPUT);
 pinMode(enBPin, OUTPUT);
 servo.attach(servoPin);
 servo.write(90);
 go(LEFT, 0);
 go(RIGHT, 0);
 testMotors();
 servo.write(sensorAngle[0]);
 delay(200);
 for (unsigned char i = 0 ; i < NUM_ANGLES ; i ++)
 readNextDistance(), delay (200);
}
void loop () {
 //IR Receiver:
 if (irrecv.decode(&signals)) {
 Serial.println(signals.value);
 irrecv.resume();
 if (signals.value == 0xFFA25D) {
 Serial.println("yeees");
 }
 }
 readNextDistance ();
 
 unsigned char tooClose = 0;
 for (unsigned char i = 0 ; i < NUM_ANGLES ; i++)
 if (distance[i] < 200)
 tooClose = 1;
 
 if (tooClose) {
 go(LEFT, 180);
 go(RIGHT, -80);
 } else {
 go(LEFT, -180);
 go(RIGHT, 180);
 }
 delay (50);
}

• Greenonline: Are you saying that the code that works correctly is only different because it is missing the lines commented with //IR Receiver? Maybe you should also post the working code (that doesn't have the IR receiver code included), so that we may compare the two versions ourselves?
• AugustinS: @Greenonline Yes, exactly. If you remove the few lines commented with //IR Receiver, then you have the working code.
• AugustinS: It seems to be the motors conflicting with the IRremote library, due to both usage of same timers. Need to find another library or find a way to make it use another timer
• Greenonline: Please post that as an answer

Answer 1

Finally found the problem: it is due to the IRremote library using the same timers than the Servo.

Solutions are to change the specified timer that the IRremote library uses in the library files (didn't work for me though) or to not use a library for either the IR receiver or the Servo or to change the physical connection of the component plugged in a pin also used by a timer.

Link to an Arduino Forum post suggesting an alternative for controlling the Servo without a library