Need help with motor driver programming

Posted by: @zefd

↑

I am trying to convert a sketch that uses the dual L298 dual motor driver shield and replace the shield with two L298N motor drivers. I have figured out (I think) the PWM signals and the motor functions, but I don't understand where the 74HC595N 8-Bit Shift Register DIR_CLK, DIR_EN, DATA, and DIR_LATCH are set up. I am using four gear motors and mecanum wheels.

const int PWM2A = 11;      //M1 motor PWM signal pin
const int PWM2B = 3;       //M2 motor PWM signal pin
const int PWM0A = 6;       //M3 motor PWM signal pin
const int PWM0B = 5;       //M4 motor PWM signal pin
const int DIR_CLK = 4;     // Data input clock line
const int DIR_EN = 7;      //Equip the L293D enabling pins
const int DATA = 8;        // USB cable
const int DIR_LATCH = 12;  // Output memory latch clock

const int Move_Forward = 39;       //Move Forward
const int Move_Backward = 216;     //Move Backward
const int Left_Move = 116;         //Left translation
const int Right_Move = 139;        //Right translation
const int Right_Rotate = 149;      //Rotate Right
const int Left_Rotate = 106;       //Rotate Left
const int Stop = 0;                //Stop
const int Upper_Left_Move = 36;    //Upper Left Move
const int Upper_Right_Move = 3;    //Upper Right Move
const int Lower_Left_Move = 80;    //Lower Left Move
const int Lower_Right_Move = 136;  //Lower Right Move
const int Drift_Left = 20;         //Drift on Left
const int Drift_Right = 10;        //Drift on Right

int Speed1 = 255;//Set the default speed between 1 and 255
int Speed2 = 255;//Set the default speed between 1 and 255
int Speed3 = 255;//Set the default speed between 1 and 255
int Speed4 = 255;//Set the default speed between 1 and 255

void Motor(int Dir, int Speed1, int Speed2, int Speed3, int Speed4) {
  analogWrite(PWM2A, Speed1);  //Motor PWM speed regulation
  analogWrite(PWM2B, Speed2);  //Motor PWM speed regulation
  analogWrite(PWM0A, Speed3);  //Motor PWM speed regulation
  analogWrite(PWM0B, Speed4);  //Motor PWM speed regulation

  digitalWrite(DIR_LATCH, LOW);            //DIR_LATCH sets the low level and writes the direction of motion in preparation
  shiftOut(DATA, DIR_CLK, MSBFIRST, Dir);  //Write Dir motion direction value
  digitalWrite(DIR_LATCH, HIGH);           //DIR_LATCH sets the high level and outputs the direction of motion
}

void setup() 
{
  pinMode(DIR_CLK, OUTPUT);
  pinMode(DATA, OUTPUT);
  pinMode(DIR_EN, OUTPUT);
  pinMode(DIR_LATCH, OUTPUT);
  pinMode(PWM0B, OUTPUT);
  pinMode(PWM0A, OUTPUT);
  pinMode(PWM2A, OUTPUT);
  pinMode(PWM2B, OUTPUT);
}

void loop() 
{
  Motor(Right_Rotate, Speed1, Speed2, Speed3, Speed4);
  delay(2000);
  Motor(Stop, 0, 0, 0, 0);
  delay(1000);
  
  Motor(Left_Rotate, Speed1, Speed2, Speed3, Speed4);
  delay(2000);
  Motor(Stop, 0, 0, 0, 0);
  delay(1000);
  
  // Motor(Move_Forward, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
  
  // Motor(Move_Backward, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
  
  // Motor(Left_Move, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
  
  // Motor(Right_Move, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
  
  // Motor(Upper_Left_Move, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
  
  // Motor(Upper_Right_Move, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
  
  // Motor(Lower_Left_Move, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
  
  // Motor(Lower_Right_Move, Speed1, Speed2, Speed3, Speed4);
  // delay(1000);
  // Motor(Stop, 0, 0, 0, 0);
  // delay(1000);
}

 

 

-- attachment is not available --
-- attachment is not available --
-- attachment is not available --

The L298N modules require two direction pins (IN1/IN2) per motor. So for 4 motors, you’ll need 8 digital pins for direction plus 4 PWM pins.

The current sketch uses the 74HC595N shift register to serialize motor direction control bits (like IN1/IN2 for each motor), using:

• DATA (pin 8): serial data line

• DIR_CLK (pin 4): clock line

• DIR_LATCH (pin 12): latch to output buffer

• DIR_EN (pin 7): enable signal for the motor driver

This approach shifts one byte (Dir) to the shift register to set all 4 motor directions (IN1/IN2 for each motor) using only 3 control lines, thanks to the shift register.

@aliarifat thank you, my original idea was to control all motors with dedicated pins, even though I will be using a Mega 2560 (needing the four interrupts for motor encoders). You got me thinking, maybe using a 74HC595N 8-Bit Shift Register might make things easier and cleaner. This would leave more pins for sensors.

Posted by: @zefd

↑

@aliarifat thank you, my original idea was to control all motors with dedicated pins, even though I will be using a Mega 2560 (needing the four interrupts for motor encoders). You got me thinking, maybe using a 74HC595N 8-Bit Shift Register might make things easier and cleaner. This would leave more pins for sensors.

If you need to drive tens or hundreds of outputs / read tens or hundreds of inputs from a single prototype board, the daisy-chain shift I/O board can be useful for your purpose. You can use a board like this:

https://www.pcbway.com/project/shareproject/Daisy_Chain_Shift_IO_Board.html

This is an easily daisy-chainable shift I/O board for your multi-input / output projects using standard SN74HC595N and CD4021BE chips!