Best/easiest way to use an Arduino to run a 3v dc motor
I really don’t want to spend a lot of money because this is for a physics project
All i need the Arduino to do is turn the motor on for X amount of time then turn the motor off
I have the Arduino Diecimila and 2 breadboards
After doing some research i think im going to use the L293D or should be using the L293NE
Thanks for all the help
~Alfa
Those motor driver chips should be OK, but you can do it more simply by using a single transistor, connected to a digital output pin via a resistor. You’ll still need a back-EMF protection diode, too.
thanks for the response which transistor are you referring to ? also could you further explain the back emf protection diode ?
You will need a transistor with a current rating high enough for the motor you’re using. The back-EMF protection diode is require will all inductive loads. It’s a reverse biased diode connected in parallel with the load. If you have a search on the forum for relay driver circuits, you’ll see what I mean – just swap the relay coil for a motor!
I really don’t want to spend a lot of money because this is for a physics project
As an ex Physics Lecturer I take exception to this. Physics is wonderful and is worth mortgaging you Granny for.
check the schematics on this page, to see how you can do it with a TIP120 transistor + 1 diode and one resistor
http://itp.nyu.edu/physcomp/Tutorials/HighCurrentLoads
Other tansistors with the current rating needed will do the job as well
I found 2x L293D in a stack of IC’s
so i think ill be using those any idea of some good tutorials? iv never written code before
thanks for the help
i realized half way to school today i should have googled “Arduino L293”
Thanks for the help! Now when i work on the programing ill be back again.
I need some help with the code
I used this tutorial:
http://itp.nyu.edu/physcomp/Labs/DCMotorControl
int switchPin = 2; // switch input
int motor1Pin = 3; // H-bridge leg 1 (pin 2, 1A)
int motor2Pin = 4; // H-bridge leg 2 (pin 7, 2A)
int enablePin = 9; // H-bridge enable pin
int ledPin = 13; // LED
void setup() {
// set the switch as an input:
pinMode(switchPin, INPUT);
// set all the other pins you're using as outputs:
pinMode(motor1Pin, OUTPUT);
pinMode(motor2Pin, OUTPUT);
pinMode(enablePin, OUTPUT);
pinMode(ledPin, OUTPUT);
// set enablePin high so that motor can turn on:
digitalWrite(enablePin, HIGH);
// blink the LED 3 times. This should happen only once.
// if you see the LED blink three times, it means that the module
// reset itself,. probably because the motor caused a brownout
// or a short.
blink(ledPin, 3, 100);
}
void loop() {
// if the switch is high, motor will turn on one direction:
if (digitalRead(switchPin) == HIGH) {
digitalWrite(motor1Pin, LOW); // set leg 1 of the H-bridge low
digitalWrite(motor2Pin, HIGH); // set leg 2 of the H-bridge high
}
// if the switch is low, motor will turn in the other direction:
else {
digitalWrite(motor1Pin, HIGH); // set leg 1 of the H-bridge high
digitalWrite(motor2Pin, LOW); // set leg 2 of the H-bridge low
}
}
/*
blinks an LED
*/
void blink(int whatPin, int howManyTimes, int milliSecs) {
int i = 0;
for ( i = 0; i < howManyTimes; i++) {
digitalWrite(whatPin, HIGH);
delay(milliSecs/2);
digitalWrite(whatPin, LOW);
delay(milliSecs/2);
}
}
I would like a switch to start the motor, that way i can have it go ASAP and not have to wait till the Arduino boots up . How can i do this?
Thanks
I would like a switch to start the motor, that way i can have it go ASAP and not have to wait till the Arduino boots up
How long does it take the Arduino to boot up? Must be all of 1 second, what’s the hurry or am I missing something?
I think Alfa is referring to the bootloader delay (4 or 5 seconds) before his software actually starts.
thanks for the responses, i am referring to bootloader delay
Ok so i tried to get it so when the switch is toggled it digitalWrite(enablePin, HIGH);
The when its toggled again its set to digitalWrite(enablePin, LOW); but this doesnt do anything. What am thinking wrong here… 
int switchPin = 2; // switch input
int motor1Pin = 3; // H-bridge leg 1 (pin 2, 1A)
int motor2Pin = 4; // H-bridge leg 2 (pin 7, 2A)
int enablePin = 9; // H-bridge enable pin
int ledPin = 13; // LED
void setup() {
// set the switch as an input:
pinMode(switchPin, INPUT);
// set all the other pins you're using as outputs:
pinMode(motor1Pin, OUTPUT);
pinMode(motor2Pin, OUTPUT);
pinMode(enablePin, OUTPUT);
pinMode(ledPin, OUTPUT);
// set enablePin high so that motor can turn on:
//digitalWrite(enablePin, HIGH);
// blink the LED 3 times. This should happen only once.
// if you see the LED blink three times, it means that the module
// reset itself,. probably because the motor caused a brownout
// or a short.
blink(ledPin, 3, 100);
}
void loop() {
// if the switch is high, motor will turn on one direction:
if (digitalRead(switchPin) == HIGH) {
digitalWrite(motor1Pin, LOW); // set leg 1 of the H-bridge low
digitalWrite(motor2Pin, HIGH); // set leg 2 of the H-bridge high
digitalWrite(enablePin, HIGH);
}
// if the switch is low, motor will turn in the other direction:
else {
digitalWrite(motor1Pin, HIGH); // set leg 1 of the H-bridge high
digitalWrite(motor2Pin, LOW); // set leg 2 of the H-bridge low
digitalWrite(enablePin, LOW);
}
}
/*
blinks an LED
*/
void blink(int whatPin, int howManyTimes, int milliSecs) {
int i = 0;
for ( i = 0; i < howManyTimes; i++) {
digitalWrite(whatPin, HIGH);
delay(milliSecs/2);
digitalWrite(whatPin, LOW);
delay(milliSecs/2);
}
}
Ok so I got the switch to work
int switchPin = 2; // switch input
int motor1Pin = 3; // H-bridge leg 1 (pin 2, 1A)
int motor2Pin = 4; // H-bridge leg 2 (pin 7, 2A)
int enablePin = 9; // H-bridge enable pin
int ledPin = 13; // LED
void setup() {
// set the switch as an input:
pinMode(switchPin, INPUT);
// set all the other pins you're using as outputs:
pinMode(motor1Pin, OUTPUT);
pinMode(motor2Pin, OUTPUT);
pinMode(enablePin, OUTPUT);
pinMode(ledPin, OUTPUT);
// set enablePin high so that motor can turn on:
digitalWrite(enablePin, HIGH);
// blink the LED 3 times. This should happen only once.
// if you see the LED blink three times, it means that the module
// reset itself,. probably because the motor caused a brownout
// or a short.
blink(ledPin, 3, 100);
}
void loop()
{ // if the switch is high, motor will turn on one direction:
if (digitalRead(switchPin) == HIGH)
{
digitalWrite(motor1Pin, LOW); // set leg 1 of the H-bridge low
digitalWrite(motor2Pin, HIGH); // set leg 2 of the H-bridge high
blink(ledPin, 3, 100);
digitalWrite(motor1Pin, LOW);
digitalWrite(motor2Pin, LOW);
} // if the switch is low, motor will turn in the other direction:
else {
digitalWrite(motor1Pin, LOW); // set leg 1 of the H-bridge high
digitalWrite(motor2Pin, LOW); // set leg 2 of the H-bridge low
blink(ledPin, 3, 100);
digitalWrite(motor1Pin, LOW);
digitalWrite(motor2Pin, LOW);
}
}
/*
blinks an LED
*/
void blink(int whatPin, int howManyTimes, int milliSecs) {
int i = 0;
for ( i = 0; i < howManyTimes; i++) {
digitalWrite(whatPin, HIGH);
delay(milliSecs/2);
digitalWrite(whatPin, LOW);
delay(milliSecs/2);
}
}
Now it works just right, the switch turns the motor on and off 
Now i need help writing a working timer loop, so that after the motor is turned on it only runs for X amount of time