Arduino Uno with H-bridge

Projects General Guidance
1

Hey everyone,

This is my first ever project but I am having problems getting my motor to run.

This is the sketch I uploaded to the board

// Project 1 - LED Flasher
int input1 = 5;
int input2 = 7;
int enableA = 6;


void setup() {
  pinMode(input1, OUTPUT);
  pinMode(input2, OUTPUT);
  pinMode(enableA, OUTPUT);
}
void loop() {
  digitalWrite(enableA, HIGH);
  digitalWrite(input1, HIGH);
  digitalWrite(input2, HIGH);
  
  delay(1000);
  digitalWrite(input1, LOW);
  digitalWrite(input2, LOW);
  digitalWrite(enableA, LOW);
  delay(1000);
}

I have used this diagram for reference L298.jpg (image)

And this is how I have wired it up

I am trying to get my DC motor to run. Can anyone help me out?

As for a side question, can anyone confirm that we do not need to use any resistors for the l298n inputs? The board gives off 40ma for each input/output, is it okay to wire it like this without any resistors?

Thanks in advance

2

Can you confirm that that battery pack is just 3V?
That may not be enough when you take into account the H-bridge drop.

Do you have a multimeter?
If not, get one.

3

I am no expert in H-bridges, but should it not be

digitalWrite(enableA, HIGH);
digitalWrite(input1, HIGH);
digitalWrite(input2, LOW);

I mean both inputs high or low could mean a short circuit

4

AWOL:
Can you confirm that that battery pack is just 3V?
That may not be enough when you take into account the H-bridge drop.

Do you have a multimeter?
If not, get one.

Initially this Tamiya Dozer I have runs by connecting to this wired remote control which uses 3 volts (the 2 D cell batteries). Everything runs smoothly but when I remove the remote control and replace it with this, it doesn't work.

Erni:
I am no expert in H-bridges, but should it not be

digitalWrite(enableA, HIGH);
digitalWrite(input1, HIGH);
digitalWrite(input2, LOW);

I mean both inputs high or low could mean a short circuit

I just tried that but still no luck.

5

So, what does the multimeter show as the voltage at the motor at 100% PWM?

6

AWOL:
So, what does the multimeter show as the voltage at the motor at 100% PWM?

Sorry for being such a newbie but how I am suppose to test that out? The only way I can get the motor to run is connecting it with the original wires that came with the kit.

7

Just measure the voltage across the motor - unless the wires are over-long, it won't make any difference if you measure it at the IC or the motor.
I just noticed you're not using PWM, so just turn the device on.

8

I can't find the multimeter in the garage, I will have to wait until my dad comes back. But anyways, I don't know if this helps but I tried directly attaching the battery to the motor and it works. Also I have tried the same setup but instead used a 9v battery and the motor still doesn't run. Does this conclude that it is not a problem associated with a voltage drop? And BTW, don't DC motors use PWM?

9

And BTW, don't DC motors use PWM?

They can, but your code doesn't.

lso I have tried the same setup but instead used a 9v battery and the motor still doesn't run

If your motor normally takes C or D cells to move it, I doubt a 9V battery would do very much.

Does this conclude that it is not a problem associated with a voltage drop?

No.

10

When I connect ground (from arduino) to pin 8 row which is the ground for the l298n and connect the negative wire (from battery) to the same row, then connect that wire and output 1 to the motor, it runs. So something is wrong with the 0v from the battery not connecting to the l298n bridge? I have tried almost everything I can, this is the only way the motor runs with my arduino code but is isn't really in a circuit. I can't get output 2 to carry out that 0v from the battery? Is that the problem here?

11

I use some L298N Ic to drive DC motors ( They are dual H bridge drivers ie, can control 2 DC motors each )

Here is a snippet of code that works for them :, note that I have defined onboard_led_pin as pin 13, and the in_1,in_2 and enable pins as whatever they were connected to ( in_1 and in_2 are digital outputs, and enable is a pin with PWM should I choose to do speed control.

If you want the motor to do something, you call " motor_drive(DIR1,255) " or " motor_drive(1,255) " which will drive tho motor at full power n direction 1

Do you have a schematic of your setup so its easier to debug?

#define DIR1 1 // motor direction 1
#define DIR2 2 // motor direction 2
#define OFF 3 // motor off

void motor_drive (int dir, int power) // Direct hardware interface
{
switch(dir) // Determine motor driving according to passed values
{
case DIR1: // Direction 1
digitalWrite(in_1,HIGH); // Motor turns in Direction 1 at a set power (PWM on enable line)
digitalWrite(in_2,LOW);
analogWrite(enable,power);
digitalWrite(onboard_LED_pin,HIGH);
break;

case DIR2: // Direction 2
digitalWrite(in_1,LOW); // Motor turns in Direction 2 at a set power (PWM on enable line)
digitalWrite(in_2,HIGH);
analogWrite(enable,power);
digitalWrite(onboard_LED_pin,HIGH);
break;
case OFF:
digitalWrite(in_1,LOW); // Motor lines are pulled low, and enable set low
digitalWrite(in_2,LOW);
digitalWrite(enable,LOW);
digitalWrite(onboard_LED_pin,HIGH);
break;
default:
digitalWrite(in_1,LOW); // Motor lines are pulled low, and enable set low
digitalWrite(in_2,LOW);
digitalWrite(enable,LOW);
digitalWrite(onboard_LED_pin,HIGH);
break;
}
digitalWrite(onboard_LED_pin,LOW);
}

12

Thanks for the advice,

It was indeed the analogwrite(pin,speed) that was the fix. Well it worked for a few seconds only. I think it is because I am connecting the ground of the arduino to the ground of the battery incorrectly. It seems to be working only if it touches slightly or something. Anyone know a solution? When I push the wires in the breadboard completely, it doesn't work anymore.

13

Nevermind guys, the problem is with the bent h-bridge. Everything works now, Thanks for all your help.