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// DS1302 RTC IC

#include "ds1302.h"

unsigned char readbyte (void)
{
  unsigned char b, i = 8;
  
  while (i)
  {
    b >>= 1;
    DS_SCLK = 0;
    _nop_();
    if (DS_IO) b |= 0x80; // set bit
        else  b &= 0x7F; // clear bit
    i--;
    if (i) DS_SCLK = 1;
    _nop_();
  }
  return b;
}

void writebyte (unsigned char b)
{
  unsigned char i = 8;
  
  while (i)
	{
    DS_SCLK = 0;
    DS_IO = (b & 1);
    DS_SCLK = 1;
    b >>= 1;
    i--;
	}
}

unsigned char ds_readbyte(unsigned char addr)
{
// ds1302 single-byte read
	unsigned char b;

	DS_CE = 0;
	DS_SCLK = 0;
	DS_CE = 1;
  delay1us();
  writebyte(addr);  // send command
  b = readbyte();   // read byte
	return b;
}

void ds_writebyte(unsigned char addr, unsigned char dta) 
{
// ds1302 single-byte write

	DS_CE = 0;
	DS_SCLK = 0;
	DS_CE = 1;
  delay1us();
  writebyte(addr);  // send command
  writebyte(dta);   // send data
}

void ds_readburst(void)
{
// ds1302 burst-read 8 bytes into array
	unsigned char i;
  
	DS_CE = 0;
	DS_SCLK = 0;
	DS_CE = 1;
  delay1us();
  writebyte(0xBF);  // send cmd byte
// Read on falling edge.
	for (i=0; i < 9; i++) // Shift bytes
	{
		ds_rtc[i] = readbyte(); // read 
    if (i < 8) DS_SCLK = 1; // If not the last byte, otherwise DS_SCLK remains low.
	}
	DS_CE = 0;
  DS_SCLK = 0;
  DS_IO = 0;
}

void ds_writeburst(void)
{
// ds1302 burst-write 8 bytes into array
  unsigned char b, i;
  
  b = 0xBE;
	DS_CE = 0;
	DS_SCLK = 0;
	DS_CE = 1;
  delay1us();
  writebyte(b);   // send cmd byte
  for (i = 0; i < 8; i++) // Shift bytes
  {
    writebyte(ds_rtc[i]); // write bytes
  }
  DS_CE = 0;
  DS_SCLK = 0;
  DS_IO = 0;
}
//++++++++++++++++++++
// Common functions
//++++++++++++++++++++
void ds_init()
{
	unsigned char b;

// Ток заряда может изменяться от большего к меньшему значениями
//  A5h, A6h, A7h, A9h, AAh, ABh, либо отключен записью нуля.
  if (ds_readbyte(0x8F)) ds_writebyte(0x8E,0);    // Clear Write Protection bit if it's set.
	if (ds_readbyte(0x91)) ds_writebyte(0x90,0); // Trickle charger off.
  b = ds_readbyte(0x81);
	if (b & 0x80) ds_writebyte(0x80, (b & 0x7F)); // clear "Clock Halt" bit.
  b = ds_readbyte(0x85);
  if (b & 0x80) ds_writebyte(0x84, (b & 0x7F)); // Set 24 hour mode.
}

void ds_reset_clock()	// reset date, time
{
  ds_writebyte(0x80, 0x00); // Clock halt off
	ds_writebyte(0x82, 0x00); // 00 minutes
	ds_writebyte(0x84, 0x07); // 07 hours
  ds_writebyte(0x86, 0x01); // 01
	ds_writebyte(0x88, 0x01); // January
  ds_writebyte(0x8A, 0x05); // Friday
  ds_writebyte(0x8C, 0x16); // 2016
  ds_writebyte(0x8E, 0x00); // Write protect off
  ds_writebyte(0x90, 0x00); // Trickle charger off
}

void delay1us (void)		//@11.0592MHz
{
	_nop_();
}