Other Arduino Codes and Videos by Robojax

Current Sensing using Arduino Motor Shield

Current Sensing with Arduino Motor Shield

This video shows you how to use current sensing with Arduino Motor Shield.

Arduino Source for L293D motor driver (loop)

This code will run run the motor and displays the current in the serial monitor

 * Current Sensing with Arduino Motor Shield
 * Written by Ahmad Shamshiri for Robojax.com on Aug 31, 2018 at 17:40 in Ajax, Ontario, Canada
 * Watch video instruction for this code: https://youtu.be/-uQKBDTWHPM
 * This code needs watching introduction to Arduino Motor Shield
 * which you can watch it here:https://youtu.be/kIgbjyqNrV8
     This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
const int MotorPinA = 12; 
const int MotorSpeedPinA = 3;
const int MotorBrakePinA = 9;
const int currentSenseA =A0;

const int MotorPinB = 13;
const int MotorSpeedPinB = 11;
const int MotorBrakePinB = 8;
const int currentSenseB =A1;

const int CW  = HIGH;// variable for clockwise rotation
const int CCW = LOW;// variable for counterclockwise rotation

const int showComments = 1;// show comments in serial monitor
const double currentFactor = 2/3.3;// 3.3V per 2A which is 0.909

void setup() {
  // motor A pin assignment
  pinMode(MotorPinA, OUTPUT);// define motor pin as output
  pinMode(MotorSpeedPinA, OUTPUT);//define motor speed control pin
  pinMode(MotorBrakePinA, OUTPUT);// define motor brake pin

  // motor B pin assignment
  pinMode(MotorPinB, OUTPUT);
  pinMode(MotorSpeedPinB, OUTPUT);
  pinMode(MotorBrakePinB, OUTPUT); 

  Serial.begin(9600);//  seial monitor initialized 


void loop() {
  brake('B', 0); // release brake

  moveMotor('B', CW, 255);// start motor B in CW direction with 255 PWM value
  Serial.print("Current at 255:");
  double currentVB = map(analogRead(currentSenseB), 0, 1024, 0, 5000)/1000;
  double currentB = currentVB*currentFactor;// get channel B current from voltage and current factor (from data sheet)

  double currentVA = map(analogRead(currentSenseA), 0, 1024, 0, 5000)/1000;
  double currentA = currentVA*currentFactor;// get channel A current from voltage and current factor (from data sheet)
  if(currentB >1.25)
    brake('B', 1);// apply brake
    brake('B',0);// release brake
    // change the rotation direction to CCW
    moveMotor('B', CCW, 255);
  Serial.println(currentB);// print the current

}// loop end

 * Written by Ahmad Shamshiri August 29 2018 at 20:59 in Ajax, Ontario, Canada 
 * moveMotor controls the motor
  @param motor is char A or B refering to motor A or B.
  @param dir is motor direction, CW or CCW
  @speed is PWM value between 0 to 255

  Example 1: to start moving motor A in CW direction with 135 PWM value
  moveMotor('A', CW, 135);

  Example 2: to start moving motor B in CCW direction with 200 PWM value
  moveMotor('B', CCW, 200);  

void moveMotor(char motor, int dir, int speed)
  int motorPin;
  int motorSpeedPin;
  if(motor =='A')
    motorPin      = MotorPinA;
    motorSpeedPin = MotorSpeedPinA;  
    motorPin      = MotorPinB;
    motorSpeedPin = MotorSpeedPinB;     
   digitalWrite(motorPin, dir);// set direction for motor
   analogWrite(motorSpeedPin, speed);// set speed of motor   
}//moveMotor end

 * brake, stops the motor, or releases the brake
 * @param motor is character A or B
 * @param brk if  1 brake, if 0, release brake
 * example of usage:
 * brake('A', 1);// applies brake to motor A
 * brake('A', 0);// releases brake from motor A
void brake(char motor, int brk)
  if(motor =='A')
    digitalWrite(MotorBrakePinA, brk);// brake
    digitalWrite(MotorBrakePinB, brk);// brake


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