/************************************************************	
 *	Processer : Microchip PIC12C508								*
 *	Compiler : Hi-TECH PICC 8.00 PL2							*
 *	Writer : Jason Kuo											*
 *	Description : It can read/write 93LC46 (64 x 16-bit organization)	*
 *************************************************************/	
	
static volatile unsigned char	RTCC	@ 0x01;
static volatile unsigned char	TMR0	@ 0x01;
static volatile unsigned char	PCL	@ 0x02;
static volatile unsigned char	STATUS	@ 0x03;
static          unsigned char	FSR	@ 0x04;
static volatile unsigned char	OSCCAL	@ 0x05;
static volatile unsigned char	GPIO	@ 0x06;

static          unsigned char control	OPTION	@ 0x00;
static volatile	unsigned char control	TRIS	@ 0x06;

/*	STATUS bits	*/
static bit 	GPWUF	@ (unsigned)&STATUS*8+7;
static bit	PA0	@ (unsigned)&STATUS*8+5;
static bit 	TO	@ (unsigned)&STATUS*8+4;
static bit 	PD	@ (unsigned)&STATUS*8+3;
static bit 	ZERO	@ (unsigned)&STATUS*8+2;
static bit	DC	@ (unsigned)&STATUS*8+1;
static bit	CARRY	@ (unsigned)&STATUS*8+0;

/*	OPTION bits	*/
#define		GPWU	(1<<7)
#define		GPPU	(1<<6)
#define		T0CS	(1<<5)
#define		T0SE	(1<<4)
#define		PSA	(1<<3)
#define		PS2	(1<<2)
#define		PS1	(1<<1)
#define		PS0	(1<<0)

/*      OSCCAL bits     */
static volatile bit     CAL3    @ (unsigned)&OSCCAL*8+7;
static volatile bit     CAL2    @ (unsigned)&OSCCAL*8+6;
static volatile bit     CAL1    @ (unsigned)&OSCCAL*8+5;
static volatile bit     CAL0    @ (unsigned)&OSCCAL*8+4;

static volatile bit	GP5	@ (unsigned)&GPIO*8+5;
static volatile bit	GP4	@ (unsigned)&GPIO*8+4;
static volatile bit	GP3	@ (unsigned)&GPIO*8+3;
static volatile bit	GP2	@ (unsigned)&GPIO*8+2;
static volatile bit	GP1	@ (unsigned)&GPIO*8+1;
static volatile bit	GP0	@ (unsigned)&GPIO*8+0;

#define CONFIG_ADDR	0xFFF

/* code protection */
#define MCLREN		0xFFFF	// memory clear enable
#define MCLRDIS		0xFFEF	// memory clear disable

/*watchdog*/
#define WDTEN		0xFFFF	// watchdog timer enable
#define WDTDIS		0xFFFB	// watchdog timer disable

/* code protection */
#define PROTECT		0xFFF7	// protect the program code
#define UNPROTECT	0xFFFF	// do not protect the program code

/*osc configurations*/
#define EXTRC   	0xFFFF	// external resistor/capacitor
#define INTRC		0xFFFE	// internal
#define XT		0xFFFD	// crystal/resonator
#define LP		0xFFFC	// low power crystal/resonator

/* 93LC46 I/O pin define */
#define CS 	GP0		//Chip Select
#define CLK	GP1		//Serial Data Clock
#define DI	GP2		//Serial Data Input
#define DO	GP4		//Serial Data Output

void Delay(unsigned int counter);
void Pulse(void);
void StartBit(void);
void EWEN(void);
void EWDS(void);
extern void Write93LC46(unsigned char Offset_Addr, unsigned int tx_data);  
extern unsigned int Read93LC46(unsigned char Offset_Addr);
void	InitPIC(void);

#define	CLRWDT()	asm(" clrwdt")
#define	SLEEP()		asm(" sleep")

#define	___mkstr1(x)	#x
#define	___mkstr(x)	___mkstr1(x)
#define	__CONFIG(x)	asm("\tpsect config,class=CONFIG,delta=2");\
			asm("\tglobal\tconfig_word"); \
			asm("config_word"); \
			asm("\tdw "___mkstr(x))

#define __IDLOC(w)       asm("\tpsect idloc,class=IDLOC,delta=2");\
			 asm("\tglobal\tidloc_word"); \
			 asm("idloc_word"); \
			 asm("\tirpc\t__arg," ___mkstr(w)); \
			 asm("\tdw 0&__arg&h"); \
			 asm("\tendm")


__CONFIG(MCLRDIS & WDTDIS & EXTRC & PROTECT);


/*---------------------------------------------------- 
 Function : Delay 										
 Input : unsigned int (counter)								
 Output : None											
 Description : Delay routine								
 if counter=1  delay 35us , if counter=10 delay 134us, 
 if counter=100 delay 1.12ms,
 These delay is base on internal 4MHz 					
------------------------------------------------------*/      
void Delay(unsigned int counter)
{
   while(counter>0) counter--;  
}                                     


/*---------------------------------------------------- 
 Function : Pulse 										
 Input : None								
 Output : None											
 Description : Send a pulse (10) to Serial Data Clock(CLK)								
------------------------------------------------------*/      
void Pulse(void)
{
    CLK = 1;
    Delay(25);
    CLK = 0;
}

/*---------------------------------------------------- 
 Function : StartBit 										
 Input : None								
 Output : None											
 Description : 		
 1. Set Chip Select(CS) = 1 (high)
 2. Set a Start Bit(1) to Serial Data Input(DI)
------------------------------------------------------*/      
void StartBit(void)
{
    CS = 1;
    DI = 1;
    Pulse();
}

/*---------------------------------------------------- 
 Function : EWEN 										
 Input : None								
 Output : None											
 Description : 	ERASE/WRITE Enable
 ------------------------------------------------------*/      
void EWEN(void)
{
    unsigned char i,temp;

    StartBit();                  /* 1 */

    temp = 0x80;                        /* 0011xxxx ,(opcode:00, Address:11xxxx) */
    for(i=0; i<8; i++) {
        if(0x30 & temp)
            DI = 1;
        else
            DI = 0;
        Pulse();
        temp >>= 1;
    }

    CS = 0;
}

/*---------------------------------------------------- 
 Function : EWDS 										
 Input : None								
 Output : None											
 Description : 	ERASE/WRITE Disable
 ------------------------------------------------------*/      
void EWDS(void)
{
    unsigned char i;

    StartBit();                  /* 1 */

    DI = 0;                       /* 0000xxxx, (opcode:00, Address:00xxxx) */
    for(i=0; i<8; i++)
        Pulse();

    CS = 0;
}

/*---------------------------------------------------- 
 Function : Write93LC46 										
 Input : unsigned char Offset Address, unsigned int tx_data								
 Output : None											
 Description : 	Write 16bits data in to 93LC46 Offset Address
 ------------------------------------------------------*/      
void Write93LC46(unsigned char Offset_Addr, unsigned int tx_data)
{
    unsigned char Addr, i;
    unsigned int temp;

    EWEN();

    StartBit();                  /* 1 */
    Offset_Addr=Offset_Addr&0x3F; /* 6bits address */
    Addr = Offset_Addr + 0x40;          /* 01AAAAAA ,(opcode:01, address:AAAAAA) */
    temp = 0x0080;
    for(i=0; i<8; i++) {
        if(Addr & temp)
            DI = 1;
        else
            DI = 0;
        Pulse();
        temp >>= 1;
    }

    temp = 0x8000;                      /* DDDDDDDDDDDDDDDD(16bits data)*/
    for(i=0; i<16; i++) {
        if(tx_data & temp)
            DI = 1;
        else
            DI = 0;
        Pulse();
        temp >>= 1;
    }
    CS = 0;

    EWDS();
}

/*---------------------------------------------------- 
 Function : Read93LC46 										
 Input : unsigned char Offset Address
 Output : unsigned int											
 Description : 	Read 16bits data from 93LC46 offset address
 ------------------------------------------------------*/      
unsigned int Read93LC46(unsigned char Offset_Addr)
{
    unsigned char Addr, i, temp;
    unsigned int  rx_data;

    StartBit();                   /* 1 */
    Offset_Addr = Offset_Addr&0x3F; /* 6bits address */
    Addr = Offset_Addr + 0x80;           /* 10AAAAAA ,(opcode:10, address:AAAAAA) */
    temp = 0x80;
    for(i=0; i<8; i++) {
        if(Addr & temp)
            DI = 1;
        else
            DI = 0;
        Pulse();
        temp >>= 1;
    }

    rx_data = 0x0000;                    /* DDDDDDDDDDDDDDDD(16bits data)*/
    for(i=0; i<16; i++) {
        Pulse();
        if(DO)
            rx_data |= 0x0001;
        if(i < 15)
            rx_data <<= 1;
    }
    CS = 0;

    return(rx_data);
}

void	InitPIC(void)
{
    OPTION = (GPWU | GPPU | PS2 | PS1 | PS0);
    TRIS = 0x10;   	
    CS = 0;
    CLK = 0;
    DI = 0;    
}

/* Main routine */
void main(void)
{
	unsigned char addr;
	unsigned int rx_buf;
	
	InitPIC();
	/* Read a word then +1 and write back to 93LC46 */
	for (addr = 0; addr < 10; addr++)
	{
		rx_buf = Read93LC46(addr);
		rx_buf = rx_buf+1;
		Write93LC46(addr, rx_buf);
	}

}