i2cmsu.c

* Use 10 MHz crystal frequency. * Use Timer0 for ten millisecond looptime. * Blink "Alive" LED e

#ifndef I2CMSU_C
#define I2CMSU_C

/* I2C lib

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

 */

#include "i2cmsu.h"

#include "delay.h"

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

#define I2C_IDLE_ERR      1
#define I2C_START_ERR     2
#define I2C_RSTART_ERR    3
#define I2C_STOP_ERR      4
#define I2C_GET_ERR       5
#define I2C_PUT_ERR       6
#define I2C_MISSACK_ERR   7
#define I2C_ACK_ERR       8
#define I2C_NAK_ERR      9


// error variable for acknowledge
#if defined(HI_TECH_C)
persistent char i2c_errstat;
#endif 

#if defined(__18CXX)
//assume MCC18 linking with startup code that only
//does explicit variable initialization
char i2c_errstat;
#endif



void i2c_init(char bitrate){
  // enable I2C Master Mode
  SSPM3 = 1; SSPM2 = 0;SSPM1 = 0; SSPM0 = 0;
  SSPADD = bitrate;  // set bus clk
  SSPEN = 1;
  bitset(TRISC,3);
  bitset(TRISC,4);  // SDA, SCL pins are inputs
  SSPIF = 0;  // clear SPIF bit
  i2c_errstat = 0; // clear error status
}



void i2c_idle(void){ // wait for idle condition 
  unsigned char byte1;
  unsigned char byte2;
  CLRWDT();
  i2c_errstat = I2C_IDLE_ERR;
  do {
      // byte1 has R/W bit.
      byte1 = SSPSTAT & 0x04;  
      byte2 = SSPCON2 & 0x1F;
    }while (byte1 | byte2);
  CLRWDT();
  i2c_errstat = 0;
  return;
}


void i2c_start(void){
  i2c_idle();
  i2c_errstat = I2C_START_ERR;
  SEN = 1;   // initiate start
  // wait until start finished
  while (SEN);
  CLRWDT();
  i2c_errstat = 0;
}

void i2c_rstart(void){// repeated start
  i2c_idle();
  i2c_errstat = I2C_RSTART_ERR;
  RSEN = 1;   // initiate start
  // wait until start finished
  while (RSEN);
  CLRWDT();
  i2c_errstat = 0;
}

void i2c_stop(void) {
  i2c_idle();
  i2c_errstat = I2C_STOP_ERR;
  PEN=1;     // initiate stop, PEN=1
  //wait until stop finished 
  while (PEN);
  CLRWDT();
  i2c_errstat = 0;
}

unsigned char i2c_put(unsigned char byte ) { 
  i2c_errstat = I2C_PUT_ERR;
  SSPIF = 0;     //clear interrupt flag
  SSPBUF = byte; // write byte
  while(!SSPIF); // wait for finish an ack
  i2c_errstat = 0;
  CLRWDT(); 
  if (ACKSTAT) {
    //no acknowledge returned, so reset
    i2c_errstat = I2C_MISSACK_ERR;
    RESET();   //asm("reset")
  }
  return(0); 
}

unsigned char i2c_put_noerr(unsigned char byte ) { 
  i2c_errstat = I2C_PUT_ERR;
  SSPIF = 0;     //clear interrupt flag
  SSPBUF = byte; // write byte
  while(!SSPIF); // wait for finish an ack
  i2c_errstat = 0;
  CLRWDT(); 
  if (ACKSTAT) return(1);
   return(0); 
}

unsigned char i2c_putbyte(unsigned char byte) {
  i2c_idle();
  return(i2c_put(byte));
}


void i2c_ack(unsigned char ackbit){
  // send acknowledge 
  CLRWDT();
  ACKDT = ackbit;
  if (ackbit)   i2c_errstat = I2C_NAK_ERR;
  else i2c_errstat = I2C_ACK_ERR;
  //initiate acknowlege cycle
  ACKEN = 1; 
  // wait until acknowledge cycle finished
  while(ACKEN);  
  CLRWDT();
  i2c_errstat = 0;
}

unsigned char i2c_get(unsigned char ackbit) {
  unsigned char byte;
  
  i2c_errstat = I2C_GET_ERR;
  RCEN = 1;  //initiate read event
  while(RCEN); // wait until finished
  CLRWDT();
  while (!BF); //also check buffer full
  CLRWDT();
  byte = SSPBUF;  // read data 
  i2c_errstat = 0;
  i2c_ack(ackbit);
  return(byte);
}

unsigned char i2c_getbyte(unsigned char ackbit) {
  i2c_idle();
  return(i2c_get(ackbit));
}

void i2c_print_err(void){
  pcrlf();
  printf((char * const)"I2C bus error is  ");
  switch (i2c_errstat) {
  case 0: printf((char * const)"None");break;
  case I2C_IDLE_ERR : printf((char * const)"Idle");break;
  case I2C_START_ERR : printf((char * const)"Start");break;
  case I2C_STOP_ERR  : printf((char * const)"Stop");break;
  case I2C_GET_ERR   : printf((char * const)"Get");break;
  case I2C_PUT_ERR   : printf((char * const)"Put");break;
  case I2C_MISSACK_ERR  : printf((char * const)"Missing Ack");break;
  case I2C_ACK_ERR   : printf((char * const)"Ack");break;
  case I2C_NAK_ERR  : printf((char * const)"Nak");break;
  default: printf((char * const)"Unknown");
  }
  pcrlf();
}

#endif