//************************************************************
//
// Title: OTP Controlled Sound ( Bit Banging A Boomer ) 
//
// Compiler Used: ByteCraft COP8C compiler version 2.0
//
//
// Description:
//
//   Embedded code for the OTP Controlled Sound reference design.
//   The code is able to fully control the LM4835 boomer amplifier.
//
// By: Wallace Ly
//
//   Audio Applications Engineer
//   National Semiconductor Corporation
//   2900 Semiconductor Drive
//   Santa Clara, 95052-8090
//
// Date Modified:
//   11/22/98
//   11/27/98
//
//*************************************************************

// Some constant definitions

#define SD 0
#define Mode 1
#define Mute 2

#define Beep 0
#define HP_Sense 1
#define Headphone 2
#define MAX 255

// Include the library file for the COP8SGR7 microcontroller

#include "cop8sgr7.h"


// Prototype definition(s)

static void wait();

void main(void){

// Setup of local variables
char volume_hi=50;
char volume_lo=50;

char state=0;


// For Shutdown Mode
PORTDD.SD=0;


// For Mode Select
PORTDD.Mode=1;


// For Mute Control
PORTDD.Mute=0;


// For Headphone Sense - Data Out 0
PORTLC.HP_Sense=1;
PORTLD.HP_Sense=0;


// For Headphone Reading
// Setup as high impedence input
PORTLC.Headphone=0; 
PORTLD.Headphone=1;


// For button one - high impedence mode
PORTFC.0=0;
PORTFD.0=1;


// For button two - high impedence mode
PORTFC.1=0;
PORTFD.1=1;


// For DC Volume Control - Set it in output
PORTGC.3=1;
PORTGD.3=1;


// INITIAL TIMER CONFIG
// IN THE INCLUDE FILE
// Note: Cop8 Microcontrollers allow up to 16 bit timer
// accuracy!


// Start the timer at zero

TMRLO=0;
TMRHI=0;


T1RAHI=0;
T1RALO=50;

T1RBHI=0;
T1RBLO=50;



    // SET THE CONTROL BITS FOR PWM, T1A Toggle
	CNTRL=0B10100000;

    // Start Timer T1
    CNTRL.T1C0=1;




while (1){

	// Scan the buttons

    while (!PORTFP.0){
	       state=1; 	// Button one was depressed
		wait();
		}
	
    while (!PORTFP.1){  // Button two was depressed
	       state=2;
	       wait();
	       }

	

	// Detect which button was depressed


	switch (state) {
	
        case 1:   if (volume_hi<MAX){
                  volume_hi++;
                  volume_lo--;
			      }
                  break;

        case 2:   if (volume_hi>0){
                  volume_hi--;
                  volume_lo++;
			      }
                  break;

		default:  break;
		
		}




    // Load the new volume into the timer registers
	

        T1RALO=volume_hi;
        T1RBLO=volume_lo;


        // Null the state variable
        state=0;







    } // Close the while
} // Close the main

//****************************************************************************
// FUNCTION: wait()
// APPROACH:  This function provides a level of delay for the program
//            This function really does nothing but waste CPU Cycles.
// ***************************************************************************

void wait(){

    // A temp character - Loop it 255 times, which is approx 255ms

    char j;

    for (j=0;j<255;j++)
    {

        NOP();

    }
}