plz check this code for DS1307 interface

embeddedsiva — Tue, 10 Apr 2007 19:26:14 GMT

hi all

i used the port b pins for interfacing the RTC

can any one check this code and inform me about my mistake

#include <mc9s12xdt512.h> /* derivative information */

#include <stdio.h>
#include "Std_Types.h"

#define SDA PORTB_PB5//PTC_PTC6
#define SCL PORTB_PB6//PTC_PTC5

#define DIR_SDA DDRB_DDRB5//DDRC_DDRC6
#define DIR_SCL DDRB_DDRB6//DDRC_DDRC5
#define SPEED 4
#define HOLD   1
#define SLAVE_ADDRESS   0xD0
#define LEN             58

byte temp, dummy, RD_data, WR_data, ACK_flag, w, i;
byte own_sl_addr = 0xD0;
byte RAM_Data[LEN];

byte RTC_reg[7] @0x700;
byte Cntr_reg @0x707;
typedef struct
{
byte Sec;
byte Min;
byte Hrs;
byte Day;
byte Date;
byte Month;
byte Year;
}sRTC;

volatile sRTC RTC @ 0x700s;

#define Seconds         RTC.Sec
#define Minutes         RTC.Min
#define Hours           RTC.Hrs
#define Day             RTC.Day
#define Date            RTC.Date
#define Month           RTC.Month
#define Year            RTC.Year

#define RTC_REG_START 0x00
#define NV_RAM_START 0x08
/* Function definition */
void Init_Time_Default(void);
byte GetByte(void);
void WriteIICbus(byte data);
void Write_Control_reg(byte ctrl);
void Read_ACK(void);
void Write_ACK(void);
void StartBit(void);
void StopBit(void);
void Wait_time(byte time);
void Wait_sh(byte time);

void Init_Time_Default(void) // see datasheet of DS1307;
{
Seconds = 0x20;
Minutes = 0x10;
Hours = 0x12;
Day =0x4;      // day of week;
Date = 0x11;
Month = 0x5;
Year = 0x6;
}
//********************************************************************
void Write_Control_reg(byte ctrl) // writes Cntr_reg to RTC;
{
ACK_flag = 0;
StartBit();
WriteIICbus(SLAVE_ADDRESS);
asm("nop");
Read_ACK();
asm("nop");
if(ACK_flag !=0)
{
  StopBit();
  return;
}
WriteIICbus(7); // write address of the Control register;
Read_ACK();
if(ACK_flag !=0)
{
  StopBit();
  return;
}
WriteIICbus(ctrl); // write value into Control register;
Read_ACK();
if(ACK_flag !=0)
{
  StopBit();
  return;
}
StopBit();
}
//********************************************************************
void Read_Control_reg(void)   // reads Cntr_reg from RTC;
{
ACK_flag = 0;
StartBit();
WriteIICbus(SLAVE_ADDRESS); // RW bit = 0;
asm("nop");
Read_ACK();
asm("nop");
if(ACK_flag !=0)
{
  StopBit();
  return;
}
WriteIICbus(7); // write address of the Control register;
Read_ACK();
if(ACK_flag !=0)
{
  StopBit();
  return;
}
StartBit();
WriteIICbus(SLAVE_ADDRESS | 1); // RW bit = 1;
Read_ACK();
if(ACK_flag !=0)
{
  StopBit();
  return;
}
DIR_SDA = 0;
Cntr_reg = GetByte(); // read value from the Control register and save it;
StopBit();
}
//********************************************************************
void WriteRTC(void)
{
ACK_flag = 0;
StartBit();
WriteIICbus(SLAVE_ADDRESS);
asm("nop");
Read_ACK();
asm("nop");
if(ACK_flag !=0)
{
  StopBit();
  return;
}
WriteIICbus(0); // Starts write from address "0" in RTC (Seconds);
Read_ACK();
if(ACK_flag !=0)
{
  StopBit();
  return;
}
for(i=0;i<7;i++)
{
  WriteIICbus(RTC_reg[i]);
  Read_ACK();
  if(ACK_flag !=0)
  {
    StopBit();
    return;
  }
}
StopBit();
}
//********************************************************************
byte ReadRTCbyte(byte addr)
{
ACK_flag = 0;
StartBit();
WriteIICbus(SLAVE_ADDRESS); // RW bit = 0;
asm("nop");
Read_ACK();
asm("nop");
if(ACK_flag !=0)
{
  StopBit();
  return 0;
}
WriteIICbus(addr);
Read_ACK();
if(ACK_flag !=0)
{
  StopBit();
  return 0;
}
StartBit();
WriteIICbus(SLAVE_ADDRESS | 1); // RW bit = 1;
Read_ACK();
if(ACK_flag !=0)
{
  StopBit();
  return 0;
}
DIR_SDA = 0;
RD_data = GetByte();
StopBit();
return RD_data;
}
//********************************************************************
byte GetByte(void)
{
byte tempb, i;

tempb = 0;
for(i=0;i<8;i++)
{
  tempb = tempb << 1;
  SCL = 1;
  Wait_sh(SPEED);
  tempb = tempb | SDA;
  SCL = 0;
  Wait_sh(SPEED - HOLD);
}
return tempb;
}
//********************************************************************
void WriteIICbus(byte data)
{
byte tempb, i;

tempb = data;
for(i=0;i<8;i++)
{
  SDA = ((tempb & 0x80)>>7);
  tempb = tempb << 1;
  Wait_sh(HOLD);
  SCL = 1;
  Wait_sh(SPEED);
  SCL = 0;
  Wait_sh(SPEED - HOLD);
}
}
//********************************************************************
void Read_ACK(void)
{
DIR_SDA = 0;
Wait_sh(HOLD);
SCL = 1;
Wait_sh(SPEED);
ACK_flag = SDA;
SCL = 0;
DIR_SDA = 1;
}
//********************************************************************
void Write_ACK(void)
{
DIR_SDA = 1;
SDA = 0;
Wait_sh(HOLD);
SCL = 1;
Wait_sh(SPEED);
SCL = 0;
Wait_sh(HOLD);
}
//********************************************************************
void StartBit(void)
{
SDA = 1;
SCL = 1;
DIR_SDA = 1;
DIR_SCL = 1;
Wait_sh(SPEED);
Wait_sh(SPEED);
SDA = 0;
Wait_sh(SPEED);
SCL = 0;
Wait_sh(SPEED);
}
//********************************************************************
void StopBit(void)
{
Wait_sh(HOLD);
SCL = 1;
Wait_sh(SPEED);
SDA = 1;
}
//***************************************************************************
void Wait_time(byte time)
{
const word k = 250;
word i, temp_t = (time*k);
for (i=0;i<temp_t;i++)
    {
    asm("nop");
    }
}
//********************************************************************
void Wait_sh(byte time)
{
word i, temp_t = time;
for (i=0;i<temp_t;i++)
    {
    asm("nop");
    }
}

//********************************************************************

void main (void)
{
DDRB_DDRB6=1 ;
DDRB_DDRB5=1 ;

PERP= 0xFF;

EnableInterrupts; /* enable interrupts */

Write_Control_reg(3); // squarewave output 32.768kHz at RTC SQW pin;
Init_Time_Default();
WriteRTC();
for(;
{

  Hours   = ReadRTCbyte(2);
  Minutes = ReadRTCbyte(1);
  Seconds = ReadRTCbyte(0);


} /* loop forever */
/* please make sure that you never leave this function */
}

Re: plz check this code for DS1307 interface

mke_et — Tue, 10 Apr 2007 20:22:04 GMT

Well, sorry but I'm not a "C" programmer...

However, I thought the DS1307 was fixed at a slave address of 68h...

I also seem to remember it being pretty adamant about 100khz max speed as well, so check your I2C speed.

Re: plz check this code for DS1307 interface

embeddedsiva — Tue, 10 Apr 2007 21:16:16 GMT

thanks for ur reply

i m not using i2c

i wrote it for 2 wire communication using port B pins

if u had interfaced with ds1307 plz share the code with me

im running out of my time

Re: plz check this code for DS1307 interface

mke_et — Tue, 10 Apr 2007 23:18:37 GMT

Well, if you write your own driver direct to two pins, just remember that when you send an 'address' to the I2C bus, you only send 7 bits followed by a 0 or a 1 to indicate writing or reading as the last bit sent. I suppose you could do the same thing by sending D0 and D1 as an 8-bit byte instead of sending 68H as 7-bits followed by the 0 or 1 bit. Then waiting for either an ack or a nak.

It looks like you did that, but then, I don't know 'C'.

Message Edited by mke_et on 2007-04-1012:22 PM

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plz check this code for DS1307 interface

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Re: plz check this code for DS1307 interface