Seeeduino + 2A Motor Shield For Arduino + Grove Line sensor

Products & Technology Shields
#1

Hi,
I am trying to calibrate 2 motors with 2 grove line sensors using interrupts, trying to count the number of white stripes from the wheel.

Demo code:

//Arduino PWM Speed Control：
int E1 = 6;   
int M1 = 7;
int E2 = 5;                         
int M2 = 4;                            
int leftSensor = 0; // PIN 2 on arduino
volatile int count_left = 0;
void setup() 
{ 
    pinMode(M1, OUTPUT);   
    pinMode(M2, OUTPUT); 
    attachInterrupt(leftSensor, CountLeft, RISING );
    Serial.begin(9600);
} 

void loop() 
{ 
    digitalWrite(M1,HIGH);   
    digitalWrite(M2, HIGH);       
    analogWrite(E1, 80);   //PWM Speed Control
    analogWrite(E2, 80);   //PWM Speed Control
    Serial.println(count_left);
}
void CountLeft()
{
    count_left++;
}

In this case when the count_left variable is very high (for example the wheel is rotating 2 white strips => count_left = 80…100) , but when i move the wheel manually (deactivating the motors) the count_left is correct. 1 white stripe => count_left=1; 2 white stripes = count_left=2;

My question is why when i am using the motors the count_left is going crazy?

#2

Please show us a picture from your wheel + encoder.
Dont use serial commands inside a interrupt routine!

#3

Hi,
2012-03-11 18.43.36.jpg
pic1.jpg
2012-03-11 18.44.15.jpg

For left sensor i use port 2 and for the right senzor i use the port 3.
Is it possible that using the same 5v port and gnd from motor shield to affect the sensors?

#4

Use white tape on your wheels. The Line Sensor need a high contrast.
5V from Motor Driver must be ok if your power source (battery?) id strong enougth.

#5

The tape is not the problem because the sensors are working fine ( i used the adjustable resistor to set a suitable reference voltage to detect blue tape).

When moving the wheel with the hand the sensor detects the blue(tape) and black.
I can`t understand why the output(count) is so different with the motor shield.

Output:
Moving the wheel manually 2 black lines : count_left=2;
Moving the wheel with the motor shield 2 black lines : count_left=for example 70 (a very high value).
Why?
I will try to upload a video with my tests to see exactly what is happening.
Thanks,