L298 different output voltages

system · September 11, 2014, 12:02am

Hi, Im currently working on a project that involves the use of two 6V dc motors controlled by a L298 driver. The problem im facing is that my motors are running at different speeds which is apparently caused by different output voltages for both motors which i measured. I atached the circuit im using.
I also measured the in1, in2, in3, in4, enA, inB voltages and they seem to be fine.

Any help would be really apreciated.

l298.bmp (217 KB)

system · September 11, 2014, 12:21am

post your code. Don't ask why.

system · September 11, 2014, 12:24am

raschemmel:
post your code. Don't ask why.

If you insist, the motor control is on the bottom, btw, i already measured the pwm outputs and they are ok.

#include<Wire.h>
const int GyroA=0x68;
const byte pin_motor1_dir = 2;
const byte pin_motor1_en = 3;
const byte pin_motor2_dir = 4;
const byte pin_motor2_en = 5;
const byte pin_buzzer = 6;
const byte pin_echo = 7;
const byte pin_trigger = 8;
const byte pin_led1 = 9;
const byte pin_led2 = 10;
const byte pin_btn = 12;
const byte pin_reflex_1 = A0;
const byte pin_reflex_2 = A1;
const byte pin_reflex_3 = A2;
const byte pin_reflex_4 = A3;
byte motor1_speed = 0;
int data_ultrasonido;
int data_reflex[4];

int buttonState;
int lastButtonState = LOW;
long debounceDelay = 50;
long lastDebounceTime = 0;

float data_imu[7];
byte z = 0;
void setup()
{
pinMode(pin_motor1_dir,OUTPUT);
pinMode(pin_motor1_en,OUTPUT);
pinMode(pin_motor2_dir,OUTPUT);
pinMode(pin_motor2_en,OUTPUT);
pinMode(pin_buzzer,OUTPUT);
pinMode(pin_trigger,OUTPUT);
pinMode(pin_echo,INPUT);
pinMode(pin_led1,OUTPUT);
pinMode(pin_led2,OUTPUT);
pinMode(pin_btn,INPUT);
pinMode(pin_reflex_1,INPUT);
pinMode(pin_reflex_2,INPUT);
pinMode(pin_reflex_3,INPUT);
pinMode(pin_reflex_4,INPUT);
Wire.begin();
Wire.beginTransmission(GyroA);
Wire.write(0x6B);
Wire.write(0); //Wake up
Wire.endTransmission(true);
//digitalWrite(pin_buzzer,HIGH);
//digitalWrite(pin_led1,HIGH);
//digitalWrite(pin_led2,HIGH);
Serial.begin(9600);
}
void loop()
{
//delay(350);
//debug_imu();
//debug_reflex();
//debug_ultrasonido();
debounce();

}
void debug_reflex()
{
sensar_reflex();
for(int i = 0;i<4;i++)
{
Serial.print("Reflex ");
Serial.print(i);
Serial.print(": ");
Serial.println(data_reflex*);*

}*

Serial.println();*
}
void debug_ultrasonido()
{

sensar_ultrasonido();*

Serial.print("Distancia: ");*

Serial.println(data_ultrasonido);*

Serial.println();*
}
void debug_imu()
{

sensar_imu();*

Serial.print("AcX: ");*

Serial.println(data_imu[2]);*

Serial.print("AcY: ");*

Serial.println(data_imu[1]);*

Serial.print("AcZ: ");*

Serial.println(data_imu[0]);*

Serial.print("GyX: ");*

Serial.println(data_imu[3]);*

Serial.print("GyY: ");*

Serial.println(data_imu[4]);*

Serial.print("GyZ: ");*

Serial.println(data_imu[5]);*

Serial.print("Temp: ");*

Serial.println(data_imu[6]);*

Serial.println();*
}
void sensar_ultrasonido()
{

long duration;*

digitalWrite(pin_trigger, LOW);*

delayMicroseconds(2);*

digitalWrite(pin_trigger, HIGH);*

delayMicroseconds(10);*

digitalWrite(pin_trigger, LOW);*

duration = pulseIn(pin_echo, HIGH,11765);*

if(duration!=0)*

{*

data_ultrasonido = duration/59;*

}*

else*

{*

data_ultrasonido = -1;*

}*
}
void sensar_reflex()
{

data_reflex[0] = analogRead(pin_reflex_1);*

data_reflex[1] = analogRead(pin_reflex_2);*

data_reflex[2] = analogRead(pin_reflex_3);*

data_reflex[3] = analogRead(pin_reflex_4);*
}
void sensar_imu()
{

Wire.beginTransmission(GyroA);*

Wire.write(0x3B);*

Wire.endTransmission(false);*

Wire.requestFrom(GyroA,14,true);*
data_imu[0] = Wire.read()*256+Wire.read();
data_imu[1]=Wire.read()*256+Wire.read();
data_imu[2]=Wire.read()*256+Wire.read();
data_imu[6]=(Wire.read()*256+Wire.read())/340.00+36.53;
data_imu[3]=Wire.read()*256+Wire.read();
data_imu[4]=Wire.read()*256+Wire.read();
data_imu[5]=Wire.read()*256+Wire.read();

data_imu[3]/=131;*

data_imu[4]/=131;*

data_imu[5]/=131;*

data_imu[0]/=16384;*

data_imu[1]/=16384;*

data_imu[2]/=16384;*
}
void debounce()
{

int state = digitalRead(pin_btn);*

if(state!=lastButtonState)*

{*

lastDebounceTime = millis();*

}*

if ((millis() - lastDebounceTime) > debounceDelay)*

{*

if (state != buttonState)*

{*

buttonState = state;*

if (buttonState == HIGH)*

{*

//tone(pin_buzzer,1760,50);*

if(motor1_speed < 255)*

{*

motor1_speed+=51;*

}*

else*

{*

motor1_speed = 0;*

}*

analogWrite(pin_motor1_en,motor1_speed);*

analogWrite(pin_motor2_en,motor1_speed);*

}*

}*

}*

lastButtonState = state;*
}
[/quote]

system · September 11, 2014, 12:39am

click the MODIFY button in the upper right of the post window.
Highlight all you code.
click the "#" CODE TAGS button on the toolbar above just to the left of the QUOTE button.
click SAVE (at the bottom).
When you post code on the forum, please make a habit of using the code tags "#" button.

http://arduino.cc/en/Reference/analogWrite
WHAT DOES THIS SAY ABOUT YOUR MOTOR-2 PWM PIN ?
The frequency of the PWM signal on most pins is approximately 490 Hz. On the Uno and similar boards, pins 5 and 6 have a frequency of approximately 980 Hz.

Now do you see why I asked you to post your code ?

system · September 11, 2014, 12:44am

raschemmel:

click the MODIFY button in the upper right of the post window.
Highlight all you code.
click the "#" CODE TAGS button on the toolbar above just to the left of the QUOTE button.
click SAVE (at the bottom).
When you post code on the forum, please make a habit of using the code tags "#" button.

analogWrite() - Arduino Reference
WHAT DOES THIS SAY ABOUT YOUR MOTOR-2 PWM PIN ?
The frequency of the PWM signal on most pins is approximately 490 Hz. On the Uno and similar boards, pins 5 and 6 have a frequency of approximately 980 Hz.

Now do you see why I asked you to post your code ?

Thanks for the help, ill check if that solves it.

system · September 11, 2014, 12:48am

You know what you need to do to correct it I assume ?

system · September 11, 2014, 1:02am

raschemmel:
You know what you need to do to correct it I assume ?

I guess changing the pins so both pwm outputs operate at the same frequency?

system · September 11, 2014, 1:13am

right

system · September 11, 2014, 1:15am

raschemmel:
right

It worked, thank you for your help

system · September 11, 2014, 1:20am

That was easy wasn't it ?
Aren't you glad it wasn't a hardware problem ?
Now you see why I asked you to post your code ?

system · September 11, 2014, 1:51am

raschemmel:
That was easy wasn't it ?
Aren't you glad it wasn't a hardware problem ?
Now you see why I asked you to post your code ?

Haha yea, i honestly thought the l298 was broken, but as usual it was just one of those little details you completely ignore

system · September 11, 2014, 2:27am

Can you post the link of your particular L298 module ? I assume it is a premade module on a pcb and not a breadboarded chip , correct ?

system · September 11, 2014, 3:40am

raschemmel:
Can you post the link of your particular L298 module ? I assume it is a premade module on a pcb and not a breadboarded chip , correct ?

Yeap, here's the sparkfun link and datasheet:

system · September 11, 2014, 5:04am

You don't have a heatsink or PCB ?

system · September 11, 2014, 5:29am

raschemmel:
You don't have a heatsink or PCB ?

Im currently testing it in a breadboard, but i do have a heatsink attached to it

system · September 11, 2014, 5:57am

That's really surprising. Most people use a variation of these (one of about 10 variations with different layouts):

system · September 11, 2014, 5:59am

Oh and BTW,
This is what your code would look like if you had followed my instructions: (in Reply#3)

   #include<Wire.h>
const int GyroA=0x68; 
const byte pin_motor1_dir = 2;
const byte pin_motor1_en = 3;
const byte pin_motor2_dir = 4;
const byte pin_motor2_en = 5;
const byte pin_buzzer = 6;
const byte pin_echo = 7;
const byte pin_trigger = 8;
const byte pin_led1 = 9;
const byte pin_led2 = 10;
const byte pin_btn = 12;
const byte pin_reflex_1 = A0;
const byte pin_reflex_2 = A1;
const byte pin_reflex_3 = A2;
const byte pin_reflex_4 = A3;
byte motor1_speed = 0;
int data_ultrasonido;
int data_reflex[4];

int buttonState;
int lastButtonState = LOW;
long debounceDelay = 50;
long lastDebounceTime = 0;

float data_imu[7];
byte z = 0;
void setup()
{
  pinMode(pin_motor1_dir,OUTPUT);
  pinMode(pin_motor1_en,OUTPUT);
  pinMode(pin_motor2_dir,OUTPUT);
  pinMode(pin_motor2_en,OUTPUT);
  pinMode(pin_buzzer,OUTPUT);
  pinMode(pin_trigger,OUTPUT);
  pinMode(pin_echo,INPUT);
  pinMode(pin_led1,OUTPUT);
  pinMode(pin_led2,OUTPUT);
  pinMode(pin_btn,INPUT);
  pinMode(pin_reflex_1,INPUT);
  pinMode(pin_reflex_2,INPUT);
  pinMode(pin_reflex_3,INPUT);
  pinMode(pin_reflex_4,INPUT);
  Wire.begin();
  Wire.beginTransmission(GyroA);
  Wire.write(0x6B);
  Wire.write(0); //Wake up
  Wire.endTransmission(true);
  //digitalWrite(pin_buzzer,HIGH);
  //digitalWrite(pin_led1,HIGH);
  //digitalWrite(pin_led2,HIGH);
  Serial.begin(9600);
}
void loop()
{
  //delay(350);
  //debug_imu();
  //debug_reflex();
  //debug_ultrasonido();
  debounce();
  
}
void debug_reflex()
{
  sensar_reflex();
  for(int i = 0;i<4;i++)
  {
    Serial.print("Reflex ");
    Serial.print(i);
    Serial.print(": ");
    Serial.println(data_reflex);
  }
  Serial.println();
}
void debug_ultrasonido()
{
  sensar_ultrasonido();
  Serial.print("Distancia: ");
  Serial.println(data_ultrasonido);
  Serial.println();
}
void debug_imu()
{
  sensar_imu();
  Serial.print("AcX: ");
  Serial.println(data_imu[2]);
  Serial.print("AcY: ");
  Serial.println(data_imu[1]);
  Serial.print("AcZ: ");
  Serial.println(data_imu[0]);
  Serial.print("GyX: ");
  Serial.println(data_imu[3]);
  Serial.print("GyY: ");
  Serial.println(data_imu[4]);
  Serial.print("GyZ: ");
  Serial.println(data_imu[5]);
  Serial.print("Temp: ");
  Serial.println(data_imu[6]);
  Serial.println();
}
void sensar_ultrasonido()
{
  long duration;
  digitalWrite(pin_trigger, LOW); 
  delayMicroseconds(2);
  digitalWrite(pin_trigger, HIGH);
  delayMicroseconds(10); 
  digitalWrite(pin_trigger, LOW);
  duration = pulseIn(pin_echo, HIGH,11765);
  if(duration!=0)
  {
    data_ultrasonido = duration/59;
  }
  else
  {
    data_ultrasonido = -1;
  }
}
void sensar_reflex()
{
  data_reflex[0] = analogRead(pin_reflex_1);
  data_reflex[1] = analogRead(pin_reflex_2);
  data_reflex[2] = analogRead(pin_reflex_3);
  data_reflex[3] = analogRead(pin_reflex_4);
}
void sensar_imu()
{
  Wire.beginTransmission(GyroA);
  Wire.write(0x3B);
  Wire.endTransmission(false);
  Wire.requestFrom(GyroA,14,true); 
  data_imu[0] = Wire.read()*256+Wire.read(); 
  data_imu[1]=Wire.read()*256+Wire.read(); 
  data_imu[2]=Wire.read()*256+Wire.read();
  data_imu[6]=(Wire.read()*256+Wire.read())/340.00+36.53; 
  data_imu[3]=Wire.read()*256+Wire.read();
  data_imu[4]=Wire.read()*256+Wire.read();  
  data_imu[5]=Wire.read()*256+Wire.read();  
  data_imu[3]/=131;
  data_imu[4]/=131;
  data_imu[5]/=131;
  data_imu[0]/=16384;
  data_imu[1]/=16384;
  data_imu[2]/=16384;
}
void debounce()
{
  int state = digitalRead(pin_btn);
  if(state!=lastButtonState)
  {
    lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > debounceDelay) 
  {
    if (state != buttonState) 
    {
      buttonState = state;
      if (buttonState == HIGH) 
      {
        //tone(pin_buzzer,1760,50);
        if(motor1_speed < 255)
        {
          motor1_speed+=51;
        }
        else
        {
          motor1_speed = 0;
        }
        analogWrite(pin_motor1_en,motor1_speed);
        analogWrite(pin_motor2_en,motor1_speed);
      }
    }
  }
  lastButtonState = state;
}
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system · September 11, 2014, 7:10am

raschemmel:
That's really surprising. Most people use a variation of these (one of about 10 variations with different layouts):
L298 H-Bridge Dual Motor Driver for sale | eBay

Yea I also have one of those but for this project (micro sumo) i needed to save as much space as possible and so im going to etch my own pcb with all the circuit

system · September 11, 2014, 7:13am

Ambitious , eh ?

system · September 11, 2014, 7:17am

raschemmel:
Ambitious , eh ?

I dont have much of a choice lol

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