//DC motor control using the L298N H-Bridge with HCS12 Tower with Channel P2 of PWM
//HCS12 Tower does not come with H-bridge driver
//We use L298N H-bridge chip (or module) for this experiment. You can buy the H-Bridge module from the following site:
//https://www.bananarobotics.com/shop/L298N-Dual-H-Bridge-Motor-Driver?gclid=CM28h-OQib0CFTBgMgod0CMAow 
//On HCS12 Tower, we connect the PP2 (PWM chan 2) to EN1 pin of L298N. And
//PT0 is connected to In1 and PT1 to In2 input pins of the L298N. 

//The L298N chip allows to have an external power source of up to 46V (4.5V-46V) to drive DC motor. DO NOT USE MORE THAN 9 V

//Steps to connect and run this program to control DC motor with L298N H-Bridge
//1)Connect an external 5V DC power to the Vss
//2)Connect the + lead of your DC motor to MOTORA1 pin 
//3)Connect the - lead of your DC motor to MOTORA2 pin
//4)Connect Ena to PP2  The PP2 is accessible via the Axiom Peripgheral board 
//5)Connect In1=PT0 Notice the PT0 is accessible via the Axiom Peripgheral board
//6)Connect In2=PT1 Notice the PT1 is accessible via the Axiom Peripgheral board

 
//Compile (F7), Download (F5) and run(F5), this program
//This program will turn the DC motor clockwise(CW) for 3 seconds,
//then it stops and turns CCW for 3 seconds. It always stops and rests for 1 second before changing direction
//It does that continuosly.       

// Written and tested by M. Mazidi.
// Tested by Brandon Collison 

//for PWM and DC motor control see chapter 17 of HCS12 book by Mazidi & Causey.    

#include <hidef.h>      /* common defines and macros */
#include "derivative.h"      /* derivative-specific definitions */


void MSDelay(unsigned int);
void main(void) 
{
  /* put your own code here */
  
    

  DDRT = 0x03;      //PORTT as output is controlled by PT0 and PT1 pins
  PTT=0b00000000;   //Stop DC motor(PT0=0 and PT1=0). 
                    //NOTICE ONLY ONE OF THEM CAN BE ON FOR TURNING CLOCKWISE (CW PT0=1) OR COUNTER CLOCKWISE (CCW PT1=1)
                    //DO NOT NOT USE PT0=1 AND PT1=1 AT THE SAME TIME.
    
  PWMPRCLK=0x30; 	//Clock B, Divide by 8,  6.25MHz/2^3 = 781.25KHz
	PWMSCLB=50;     //Clock SB scale, 2*50 = 100, 781.25KHz/100 = 7.8125KHz 
	PWMCLK=0x04; 	  //ClockB for Chan 2
	PWMPOL=0x04; 	  //high and low for polarity for Chan 2
	PWMCAE=0; 		  //Left aligned
	PWMCTL=0;		    //8-bit chan and PWM freeze during wait  
	PWMCNT2=0;		  //start the PWMCount2 with 0 value
	PWME=0x04; 	    //Enable PWM chan 2

for(;;) 
   {
  
  PWMPER2=100;	  //PWM_Period Freq. = ClockSB/100= 7.8125KHz Hz/100=78.125 Hz
  PWMDTY2=60;     //Duty Cycle=60% (60% of 100). Change this value and experiment with duty cycle.
                  //As another example, If you have a PWMPER2 = 50 and you want 60% Duty Cycle
                  //50 * 60% = 30, PWMDTY2 = 30
  PTT=0b00000001; //turn on for clockwise direction (DO NOT USE 0b00000011 FOR BOTH ON)
  MSDelay(3000);  //run for 3 sec
  PTT=0x00000000; //stop the motor
  MSDelay(1000);  //wait 1 sec for motor to stop completely before changing direction

  PTT=0b00000010; //change direction to CCW (DO NOT USE 0b00000011 FOR BOTH ON)
  MSDelay(3000);  //run for 3 sec
  PTT=0x00000000; //stop the motor.
  MSDelay(1000);  //wait 1 sec for motor to stop completely before changing direction.
  
  }
 
}


//j is for 1 msec delay (approax). Not Measured by Scope yet 
//

 void MSDelay(unsigned int itime)
  {
    unsigned int i; unsigned int j;
    for(i=0;i<itime;i++)
      for(j=0;j<1000;j++);    //1 msec (aprox..). not tested using Scope
  }