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/************************************************************************/
/* */
/* Access Dallas 1-Wire Devices */
/* */
/* Author: Peter Dannegger */
/* danni@specs.de */
/* */
/************************************************************************/
#include <util/delay.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#ifndef W1_PIN
#define W1_PIN PA0
#define W1_IN PINA
#define W1_OUT PORTA
#define W1_DDR DDRA
#endif
uint8_t buff[2];
uint8_t w1_reset(void)
{
uint8_t err;
W1_OUT &= ~(1<<W1_PIN);
W1_DDR |= 1<<W1_PIN;
_delay_us(480 ); // 480 us
cli();
W1_DDR &= ~(1<<W1_PIN);
_delay_us( 66 );
err = W1_IN & (1<<W1_PIN); // no presence detect
sei();
_delay_us( 480 - 66 );
if( (W1_IN & (1<<W1_PIN)) == 0 ) // short circuit
err = 1;
return err;
}
uint8_t w1_bit_io( uint8_t b )
{
cli();
W1_DDR |= 1<<W1_PIN;
_delay_us( 1 );
if( b )
W1_DDR &= ~(1<<W1_PIN);
_delay_us( 15 - 1 );
if( (W1_IN & (1<<W1_PIN)) == 0 )
b = 0;
_delay_us( 60 - 15 );
W1_DDR &= ~(1<<W1_PIN);
sei();
return b;
}
uint w1_byte_wr( uint8_t b )
{
uint8_t i = 8, j;
do{
j = w1_bit_io( b & 1 );
b >>= 1;
if( j )
b |= 0x80;
}while( --i );
return b;
}
uint w1_byte_rd( void )
{
return w1_byte_wr( 0xFF );
}
uint8_t w1_rom_search( uint8_t diff, uint8_t idata *id )
{
uint8_t i, j, next_diff;
uint8_t b;
if( w1_reset() )
return PRESENCE_ERR; // error, no device found
w1_byte_wr( SEARCH_ROM ); // ROM search command
next_diff = LAST_DEVICE; // unchanged on last device
i = 8 * 8; // 8 bytes
do{
j = 8; // 8 bits
do{
b = w1_bit_io( 1 ); // read bit
if( w1_bit_io( 1 ) ){ // read complement bit
if( b ) // 11
return DATA_ERR; // data error
}else{
if( !b ){ // 00 = 2 devices
if( diff > i ||
((*id & 1) && diff != i) ){
b = 1; // now 1
next_diff = i; // next pass 0
}
}
}
w1_bit_io( b ); // write bit
*id >>= 1;
if( b ) // store bit
*id |= 0x80;
i--;
}while( --j );
id++; // next byte
}while( i );
return next_diff; // to continue search
}
void w1_command( uint8_t command, uint8_t idata *id )
{
uint8_t i;
w1_reset();
if( id ){
w1_byte_wr( MATCH_ROM ); // to a single device
i = 8;
do{
w1_byte_wr( *id );
id++;
}while( --i );
}else{
w1_byte_wr( SKIP_ROM ); // to all devices
}
w1_byte_wr( command );
}
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