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Topic: VNH5019 Motor Driver - Arduino Mega 2560 - Help needed (Read 1 time) previous topic - next topic

MAAhelp

Hi,

I am having problems regarding the connection between the Arduino Mega 2560 and the Motor Driver VNH5019. I am trying to connect the Motor Driver to Timer 3 (that is pins 3&5 on the Arduino Mega),in order to use the 16-bit timer instead of the 8-bit timer which is connected to pins 9&10 which is the default connection used. I used these threads http://arduino.cc/forum/index.php?topic=77168.0 & http://forum.pololu.com/viewtopic.php?f=15&t=5806&p=27874&hilit=vnh5019#p27874 but have not been able to get both motors working.
I was previously using an Uno with the Motor Driver and did not have any problems since the 16-bit timer is connected to pins 9&10 on the Uno thus able to get the required PWM frequency (20kHz).
The motors I am using are: http://www.pololu.com/catalog/product/1103.
My set up is:
2 motors connected to the Mega via the Motor Driver powered by a 12V laptop charger which does not seem to have any problems.The connections I have are:

Digital 13      M1INA            Motor 1 direction input A
Digital 4       M1INB             Motor 1 direction input B
Digital 6       M1EN/DIAG      Motor 1 enable input/fault output
Digital 7       M2INA             Motor 2 direction input A
Digital 8       M2INB             Motor 2 direction input B
Digital 3       M1PWM           Motor 1 speed input
Digital 5       M2PWM           Motor 2 speed input
Digital 12     M2EN/DIAG      Motor 2 enable input/fault output
Analog 0       M1CS              Motor 1 current sense output
Analog 1       M2CS              Motor 2 current sense output


The header file is:

Code: [Select]
#ifndef DualVNH5019MotorShield_h
#define DualVNH5019MotorShield_h

#include <Arduino.h>

class DualVNH5019MotorShield
{
 public:
   // CONSTRUCTORS
   DualVNH5019MotorShield(); // Default pin selection
   DualVNH5019MotorShield(unsigned char INA1, unsigned char INB1, unsigned char EN1DIAG1, unsigned char CS1,
                          unsigned char INA2, unsigned char INB2, unsigned char EN2DIAG2, unsigned char CS2); // User-defined pin selection.
 
   // PUBLIC METHODS
   void init(); // Initialize TIMER 1 (or timer 3 for mega) set the PWM to 20kHZ
   void setM1Speed(int speed); // Set speed
   void setM2Speed(int speed); // Set speed
   void setSpeeds(int m1Speed, int m2Speed); // Set speed for both M1 and M2
   void setM1Brake(int brake); // Brake M1
   void setM2Brake(int brake); // Brake M2
   void setBrakes(int m1Brake, int m2Brake); // Brake both M1 and M2
   unsigned int getM1CurrentMilliamps(); // Get current reading
   unsigned int getM2CurrentMilliamps(); // Get current reading
   unsigned char getM1Fault(); // Get fault reading
   unsigned char getM2Fault(); // Get fault reading
 
 private:
   unsigned char _INA1;
   unsigned char _INB1;
 /*#if defined(__AVR_ATmega168__)|| defined(__AVR_ATmega328P__)
   static const unsigned char _PWM1 = 9;
   static const unsigned char _PWM2 = 10;
 #endif*/
 #if defined(__AVR_ATmega128__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
   static const unsigned char _PWM1 = 3;
   static const unsigned char _PWM2 = 5;
 #endif
   unsigned char _EN1DIAG1;
   unsigned char _CS1;
   unsigned char _INA2;
   unsigned char _INB2;
   unsigned char _EN2DIAG2;
   unsigned char _CS2;  
};
#endif


while the .cpp file is:
Code: [Select]

#include "DualVNH5019MotorShield.h"

// Constructors

DualVNH5019MotorShield::DualVNH5019MotorShield()
{
 //Pin map
 _INA1 = 13;
 _INB1 = 4;
 _EN1DIAG1 = 6;
 _CS1 = A0;
 _INA2 = 7;
 _INB2 = 8;
 _EN2DIAG2 = 12;
 _CS2 = A1;
}

DualVNH5019MotorShield::DualVNH5019MotorShield(unsigned char INA1, unsigned char INB1, unsigned char EN1DIAG1, unsigned char CS1,
                                              unsigned char INA2, unsigned char INB2, unsigned char EN2DIAG2, unsigned char CS2)
{
 //Pin map
 //PWM1 and PWM2 cannot be remapped because the library assumes PWM is on timer1
 _INA1 = INA1;
 _INB1 = INB1;
 _EN1DIAG1 = EN1DIAG1;
 _CS1 = CS1;
 _INA2 = INA2;
 _INB2 = INB2;
 _EN2DIAG2 = EN2DIAG2;
 _CS2 = CS2;
}

// Public Methods
void DualVNH5019MotorShield::init()
{
// Define pinMode for the pins and set the frequency for timer1.

 pinMode(_INA1,OUTPUT);
 pinMode(_INB1,OUTPUT);
 pinMode(_PWM1,OUTPUT);
 pinMode(_EN1DIAG1,INPUT);
 pinMode(_CS1,INPUT);
 pinMode(_INA2,OUTPUT);
 pinMode(_INB2,OUTPUT);
 pinMode(_PWM2,OUTPUT);
 pinMode(_EN2DIAG2,INPUT);
 pinMode(_CS2,INPUT);
// #if defined(__AVR_ATmega168__)|| defined(__AVR_ATmega328P__)
 // Timer 1 configuration
 // prescaler: clockI/O / 1
 // outputs enabled
 // phase-correct PWM
 // top of 400
 //
 // PWM frequency calculation
 // 16MHz / 1 (prescaler) / 2 (phase-correct) / 400 (top) = 20kHz
// TCCR1A = 0b10100000;
// TCCR1B = 0b00010001;
// ICR1 = 400;
// #endif
 #if defined(__AVR_ATmega128__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
 // Mega board specific stuff here - assumes assigning timer3, using pins 3 &5
 TCCR3A = 0b10100000; // Mega pin 5
 TCCR3C = 0b00010001; // Mega pin 3
 ICR3 = 400;
 #endif
}
// Set speed for motor 1, speed is a number betwenn -400 and 400
void DualVNH5019MotorShield::setM1Speed(int speed)
{
 unsigned char reverse = 0;

 if (speed < 0)
 {
   speed = -speed;  // Make speed a positive quantity
   reverse = 1;  // Preserve the direction
 }
 if (speed > 400)  // Max PWM dutycycle
   speed = 400;
//  #if defined(__AVR_ATmega168__)|| defined(__AVR_ATmega328P__)
//  OCR1A = speed;
#if defined(__AVR_ATmega128__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
 // Mega board specific stuff here - assumes assigning timer3, using pins 3 &5
 OCR3A = speed;
//  #else
//  analogWrite(_PWM1,speed * 51 / 80);
 #endif
 if (reverse)
 {
   digitalWrite(_INA1,LOW);
   digitalWrite(_INB1,HIGH);
 }
 else
 {
   digitalWrite(_INA1,HIGH);
   digitalWrite(_INB1,LOW);
 }
}

// Same as motor 1
void DualVNH5019MotorShield::setM2Speed(int speed)
{
 unsigned char reverse = 0;

 if (speed < 0)
 {
   speed = -speed;  // make speed a positive quantity
   reverse = 1;  // preserve the direction
 }
 if (speed > 400)  // Max
   speed = 400;
//  #if defined(__AVR_ATmega168__)|| defined(__AVR_ATmega328P__)
// OCR1B = speed;
 #if defined(__AVR_ATmega128__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
 // Mega board specific stuff here - assumes assigning timer3, using pins 3 &5
 OCR3C = speed;
// #else
// analogWrite(_PWM2,speed * 51 / 80);
 #endif
 if (reverse)
 {
   digitalWrite(_INA2,LOW);
   digitalWrite(_INB2,HIGH);
 }
 else
 {
   digitalWrite(_INA2,HIGH);
   digitalWrite(_INB2,LOW);
 }
}

// Set speed for motor 1 and 2
void DualVNH5019MotorShield::setSpeeds(int m1Speed, int m2Speed)
{
 setM1Speed(m1Speed);
 setM2Speed(m2Speed);
}

// Brake motor 1, brake is a number between 0 and 400
void DualVNH5019MotorShield::setM1Brake(int brake)
{
 // normalize brake
 if (brake < 0)
 {
   brake = -brake;
 }
 if (brake > 400)  // Max brake
   brake = 400;
 digitalWrite(_INA1, LOW);
 digitalWrite(_INB1, LOW);
// #if defined(__AVR_ATmega168__)|| defined(__AVR_ATmega328P__)
// OCR1A = brake;
 #if defined(__AVR_ATmega128__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
 // Mega board specific stuff here - assumes assigning timer3, using pins 3 &5
 OCR3A = brake;
// #else
// analogWrite(_PWM1,brake * 51 / 80);
 #endif
}

// Same as motor 1
void DualVNH5019MotorShield::setM2Brake(int brake)
{
 // normalize brake
 if (brake < 0)
 {
   brake = -brake;
 }
 if (brake > 400)  
   brake = 400;
 digitalWrite(_INA2, LOW);
 digitalWrite(_INB2, LOW);
//  #if defined(__AVR_ATmega168__)|| defined(__AVR_ATmega328P__)
// OCR1B = brake;
 #if defined(__AVR_ATmega128__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
 // Mega board specific stuff here - assumes assigning timer3, using pins 3 &5
 OCR3C = brake;
// #else
// analogWrite(_PWM2,brake * 51 / 80);
 #endif
}

// Brake motor 1 and 2, brake is a number between 0 and 400
void DualVNH5019MotorShield::setBrakes(int m1Brake, int m2Brake)
{
 setM1Brake(m1Brake);
 setM2Brake(m2Brake);
}

// Return motor 1 current value in milliamps.
unsigned int DualVNH5019MotorShield::getM1CurrentMilliamps()
{
 // 5V / 1024 ADC counts / 144 mV per A = 34 mA per count
 return analogRead(_CS1) * 34;
}

// Return motor 2 current value in milliamps.
unsigned int DualVNH5019MotorShield::getM2CurrentMilliamps()
{
 // 5V / 1024 ADC counts / 144 mV per A = 34 mA per count
 return analogRead(_CS2) * 34;
}

// Return error status for motor 1
unsigned char DualVNH5019MotorShield::getM1Fault()
{
 return !digitalRead(_EN1DIAG1);
}

// Return error status for motor 2
unsigned char DualVNH5019MotorShield::getM2Fault()
{
 return !digitalRead(_EN2DIAG2);
}


Strangely enough in the .cpp file changing:
Code: [Select]
TCCR3A = 0b10100000;
TCCR3C = 0b00010001;
ICR3 = 400;


to

Code: [Select]
TCCR3A = 0b10100000;
TCCR3B = 0b00010001;
ICR3 = 400;


gets one motor working but from the research I did TCCR3B should be connected to pin 2 which is not being used.

Many thanks,
MAAhelp




PaulS

Quote
I am trying to connect the Motor Driver to Timer 3 (that is pins 3&5 on the Arduino Mega),in order to use the 16-bit timer instead of the 8-bit timer which is connected to pins 9&10 which is the default connection used.

Why?

MAAhelp

To get a PWM frequency of 20kHz as opposed to the maximum of an 8-bit timer. Pololu have developed a library specific to the Arduino Mega for all those interested.

http://forum.pololu.com/viewtopic.php?f=15&t=6139


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