Conditional Interruption in a predefined path

Other Hardware Motors, Mechanics, Power and CNC
1

Hi,
I am a total dummy to arduino and programming. I am working on a project where I have 2 motors (one for each wheel of the cart) and a PING))) ultrasonic sensor connected to Arduino.
I cant figure out how I wold be able to make a program that soes the following.

The cart starts and follows a certain route. for example moves forward for 1 minute, pauses, turns left moves in reverse for 2 minutes etc etc. This part I was able to accomplish.

Now, what I would like is that, whenever the PING sensor detects a hurdle, the cart pauses in its route and when the hurdle goes away, the cart RESUMES from its last position.

What I end up with is the cart starts from the beginning instead of resuming its operation.

Thanks.

2

The problem is on line 76 of the code you didn't show.

3

Sorry. This is what I have at the moment. There are two problems here ( in my eyes):

  1. The ping test is performed only after a movement set is complete.
  2. When the there is no hurdle, the cart starts from the beginning of the movement cycle.

Thanks.

const int pingPin = 5;
unsigned int duration, inches;

int MLA = 7;
int MLB = 8;

int MRA = 2;
int MRB = 4;

int MRPWM = 9;
int MLPWM = 10;

int MREN = 6;
int MLEN = 12;

//unsigned char MRCS = A0;
//unsigned char MLCS = A1;

void setup(){
Serial.begin(115200);
pinMode (MRA, OUTPUT);
pinMode (MRB, OUTPUT);
pinMode (MRPWM, OUTPUT);
pinMode(MREN, OUTPUT);
pinMode (MLA, OUTPUT);
pinMode (MLB, OUTPUT);
pinMode (MLPWM, OUTPUT);
pinMode(MLEN, OUTPUT);


}
void loop() {
pingTest();

if (inches < 15)   {
  pause();
//  exit(0);
  }
else {
  forward();
  delay(3000);
  pause();
  delay(1000);
  left();
  delay(2000);
  pause();
  delay(1000);
  reverse();
  delay(3000);
  pause();
  delay(1000);
  }

}

void forward() {
digitalWrite(MREN,HIGH);
digitalWrite(MLEN,HIGH);

digitalWrite(MRA,HIGH);
digitalWrite(MRB,LOW);
digitalWrite(MLA,HIGH);
digitalWrite(MLB,LOW);
analogWrite(MRPWM,255); //Right Motor at full speed
analogWrite(MLPWM,255); //Left Motor at full speed
}

void reverse () {
digitalWrite(MREN,HIGH);
digitalWrite(MLEN,HIGH);

digitalWrite(MRA,LOW);
digitalWrite(MRB,HIGH);
digitalWrite(MLA,LOW);
digitalWrite(MLB,HIGH);
analogWrite(MRPWM,255); //Right Motor at full speed
analogWrite(MLPWM,255); // Left Motor at full speed
}



void left() {
digitalWrite(MREN,HIGH);
digitalWrite(MLEN,HIGH);

digitalWrite(MREN,HIGH);
digitalWrite(MLEN,HIGH);
digitalWrite(MRA,HIGH);
digitalWrite(MRB,LOW);
digitalWrite(MLA,HIGH); 
digitalWrite(MLB,LOW);
analogWrite(MRPWM,255); //Right Motor at full speed
analogWrite(MLPWM,0); // Left Motor stopped
}

void right() {
digitalWrite(MREN,HIGH);
digitalWrite(MLEN,HIGH);

digitalWrite(MRA,HIGH); 
digitalWrite(MRB,LOW);
digitalWrite(MLA,HIGH);
digitalWrite(MLB,LOW); 
analogWrite(MRPWM,0); // Right Motor stopped
analogWrite(MLPWM,255); // Left Motor at full speed
}

void pause() {
digitalWrite(MREN,LOW);
digitalWrite(MLEN,LOW);
}

void pingTest() {
  pinMode(pingPin, OUTPUT);          // Set pin to OUTPUT
  digitalWrite(pingPin, LOW);        // Ensure pin is low
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);       // Start ranging
  delayMicroseconds(5);              //   with 5 microsecond burst
  digitalWrite(pingPin, LOW);        // End ranging
  pinMode(pingPin, INPUT);           // Set pin to INPUT
  duration = pulseIn(pingPin, HIGH); // Read echo pulse
  inches = duration / 148;        // Convert to inches
  Serial.print(inches);// Display result
  Serial.print(" INCHES");
  Serial.println();  
  delay(1000);
}
4

The problem is your liberal use of the delay() function. The Arduino can do nothing during a delay. Get rid of ALL the delay()s and use millis() to manage timing without blocking as illustrated in Several Things at a Time

...R

5

Hmm. That's awesome. Now allow me a few days to go through the sketch to understand it. Thanks a lot.