/* I2C lib

   R. Reese MSU  July 2003
   
   Delay routines are from samples provided with PICC subroutines

 */

#include	<pic.h>
#include "i2cmsu.h"


#define bitset(var,bitno) ((var) |= (1 << (bitno)))
#define bitclr(var,bitno) ((var) &= ~(1 << (bitno)))
#define bittst(var,bitno) (var & (1 << (bitno)))


void
DelayMs(unsigned char cnt)
{
#if	XTAL_FREQ <= 2MHZ
	do {
		DelayUs(996);
	} while(--cnt);
#endif

#if    XTAL_FREQ > 2MHZ	
	unsigned char	i;
	do {
		i = 4;
		do {
			DelayUs(250);
		} while(--i);
	} while(--cnt);
#endif
}



/* wait for idle condition */
i2c_idle()
{

  unsigned char byte1;
  unsigned char byte2;

  do {
      byte1 = SSPSTAT & 0x04;  // gte R/W bit.
      byte2 = SSPCON2 & 0x1F;
    }while (byte1 | byte2);
  return;
}


i2c_Start(){

  i2c_idle();
  bitset(SSPCON2,0);  /* initiate start, SEN=1 */
  /* wait until start finished */
 while (bittst(SSPCON2,0));
}


i2c_Stop() {

  i2c_idle();
  bitset(SSPCON2,2);  /* initiate stop, PEN=1 */
  /* wait until stop finished */
  while (bittst(SSPCON2,2));
}


i2c_WriteTo(unsigned char addr) {

  /* first, send start */
  i2c_Start();
  SSPBUF = addr;  /* write data */
  while(bittst(SSPSTAT,2)); /* wait until finished */
  /* wait for acknowledge */
  while(bittst(SSPCON2,6)); /* wait until ack */
}



i2c_PutByte(unsigned char byte) {

  i2c_idle();
  SSPBUF = byte;  /* write data */
  while(bittst(SSPSTAT,2)); /* wait until finished */
  /* wait for acknowledge */
  while(bittst(SSPCON2,6)); /* wait until ack */
}

i2c_FastPutByte(unsigned char byte) {

  SSPBUF = byte;  /* write data */
  while(bittst(SSPSTAT,2)); /* wait until finished */
  /* wait for acknowledge */
  while(bittst(SSPCON2,6)); /* wait until ack */
}


i2c_doAck(){
  /* send acknowledge */
  bitclr(SSPCON2,5); //set ACKBIT = 0
  bitset(SSPCON2,4); //initiate acknowlege cycle
  while(bittst(SSPCON2,4));  // wait unti acknowledge cycle finished
}

i2c_doNak(){
  /* send acknowledge */
  bitset(SSPCON2,5); //set ACKBIT = 1
  bitset(SSPCON2,4); //initiate acknowlege cycle
  while(bittst(SSPCON2,4));  // wait unti acknowledge cycle finished
}

unsigned char i2c_GetByte() {

  unsigned char byte;

  i2c_idle();
  bitset(SSPCON2,3); /* initiate read event */
  while(bittst(SSPCON2,3)); /* wait until finished */
  while (!(bittst(SSPSTAT,0)));
  byte = SSPBUF;  /* read data */
  return(byte);
}


void mem_write(unsigned char cmd,unsigned char val, int addr) {

  unsigned char hbyte;
  unsigned char lbyte;

  if (addr & 0x8000) {
    // if MSB set , set block select bit
    cmd = cmd | 0x08;
  }
  hbyte = (addr >> 8) & 0x7F; // high address byte
  lbyte = (addr) & 0xFF; // low address byte
  i2c_WriteTo(cmd);  // send write cmd
  i2c_PutByte(hbyte); // send high address byte
  i2c_PutByte(lbyte); // send low address byte
  i2c_PutByte(val);   // send data 
  i2c_Stop();
  DelayMs(5);
}


/* this routine does not wait for write to finish!
   Need to be careful to only call every 5 ms
   or do end-of-write checking yourself
 */
      
void block_mem_write(unsigned char cmd,int addr, char *buf) {

  unsigned char hbyte;
  unsigned char lbyte;
  unsigned char k;
  
  if (addr & 0x8000) {
    // if MSB set , set block select bit
    cmd = cmd | 0x08;
  }
  hbyte = (addr >> 8) & 0x7F; // high address byte
  lbyte = (addr) & 0xFF; // low address byte
  i2c_WriteTo(cmd);  // send write cmd
  i2c_PutByte(hbyte); // send high address byte
  i2c_PutByte(lbyte); // send low address byte
  for (k=0;k<64;k++) {
    //i2c_PutByte(buf[k]);   // send data 
    i2c_FastPutByte(buf[k]);   // send data 
  }
  i2c_Stop();
  //DelayMs(5);  // no need to delay, will not be back here for 5 ms
}



/* random read */
unsigned char mem_read(unsigned char cmd,int addr) {

  unsigned char hbyte;
  unsigned char lbyte;
  unsigned char val;

  if (addr & 0x8000) {
    // if MSB set , set block select bit
    cmd = cmd | 0x08;
  }
  hbyte = (addr >> 8) & 0x7F; // high address byte
  lbyte = (addr) & 0xFF; // low address byte
  i2c_WriteTo(cmd);  // send write cmd, do this to set address counter
  i2c_PutByte(hbyte); // send high address byte
  i2c_PutByte(lbyte); // send low address byte
  i2c_Stop();               // send stop
  cmd = cmd | 0x1;    // set read bit
  i2c_WriteTo(cmd);  // send read cmd, address set by previous cmd
  val = i2c_GetByte();   // read data
  i2c_Stop();               // send stop
  return(val);
}

/* block read */
void block_mem_read(unsigned char cmd,int addr,char *buf) {

  unsigned char hbyte;
  unsigned char lbyte;
  unsigned char k;

  if (addr & 0x8000) {
    // if MSB set , set block select bit
    cmd = cmd | 0x08;
  }
  hbyte = (addr >> 8) & 0x7F; // high address byte
  lbyte = (addr) & 0xFF; // low address byte
  i2c_WriteTo(cmd);  // send write cmd, do this to set address counter
  i2c_PutByte(hbyte); // send high address byte
  i2c_PutByte(lbyte); // send low address byte
  i2c_Stop();               // send stop
  cmd = cmd | 0x1;    // set read bit
  i2c_WriteTo(cmd); 

  for (k=0;k<64;k++){
    buf[k] = i2c_GetByte();   // read data
    if (k== 63) i2c_Stop(); 
    else i2c_doAck();
  }
}

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