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VNH5019 Motor Driver - Arduino Mega 2560 - Help needed


#1

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 PWM Frequency - Dual VNH5019 Shield & Arduino Library 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: 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]#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 for M1.
void setM2Speed(int speed); // Set speed for M2.
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 for M1.
unsigned int getM2CurrentMilliamps(); // Get current reading for M2.
unsigned char getM1Fault(); // Get fault reading from M1.
unsigned char getM2Fault(); // Get fault reading from M2.

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[/code]

while the .cpp file is:

[code]#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);
}[/code]

Strangely enough in the .cpp file changing:

TCCR3A = 0b10100000; TCCR3C = 0b00010001; ICR3 = 400;

to

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,
siattasm


#2

Hi, Siattasm

Sorry for the delayed reply. A modified version of the VNH5019 shield library that allows for a 20kHz PWM frequency with the Arduino Mega is available in this thread.

-Claire