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/************************************************************************/
/* */
/* Access Dallas 1-Wire Devices */
/* */
/* Author: Peter Dannegger */
/* danni@specs.de */
/* */
/************************************************************************/
/* modified by Florian Jung (flo@windfisch.org).
* Changelog:
* - try to drive parasite-powered devices via avr-builtin pullup
* - DS199X access functions
*/
/* WARNING WARNING WARNING:
* this code VIOLATES THE 1-WIRE SPECIFICATION! Instead of "letting the
* line float" (which implies that it's gently pulled up to 5V by the
* pullup resistor), we're hard connecting the line against +5V, without
* any resistor in between. After some time, we let the line float, only
* held up by the (weak) AVR-internal pullup.
*
* THIS COULD DESTROY YOUR HARDWARE! you have been warned.
*
* (We do this because the internal pullup isn't strong enough to serve
* the DS1992 with power. The line is only hard-connected to +5V, when
* we're (sort of) sure that the DS1992 won't pull down the line to GND
* (since that would cause a short-circuit). Buuuut there's no guarantee,
* it just works[tm])
*/
#include <util/delay.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include "1wire.h"
#ifndef W1_PIN
#define W1_PIN PB4
#define W1_IN PINB
#define W1_OUT PORTB
#define W1_DDR DDRB
#endif
uint8_t buff[2];
#define hard_gnd do { W1_OUT &= ~(1<<W1_PIN); W1_DDR |= 1<<W1_PIN; } while(0)
#define hard_vcc do { W1_OUT |= 1<<W1_PIN; W1_DDR |= 1<<W1_PIN; } while(0)
#define soft_vcc do { W1_DDR &= ~(1<<W1_PIN); W1_OUT |= 1<<W1_PIN; } while(0)
#define tristate do { W1_DDR &= ~(1<<W1_PIN); W1_OUT &= ~(1<<W1_PIN); } while(0)
uint8_t w1_reset(void)
{
uint8_t err = 0;
hard_gnd;
_delay_us(480 ); // 480 us
cli();
hard_vcc;
_delay_us(33);
soft_vcc;
_delay_us( 66-33 );
if (W1_IN & (1<<W1_PIN)) // no presence detect
err = 1;
sei();
_delay_us( 480 - 66 );
if( (W1_IN & (1<<W1_PIN)) == 0 ) // short circuit
err = 2;
return err;
}
uint8_t w1_bit_io( uint8_t b )
{
cli();
hard_gnd;
_delay_us( 1 );
if( b )
{
hard_vcc;
_delay_us(7 );
soft_vcc;
_delay_us( 15 - 1 - 7 );
}
else
{
_delay_us( 15 - 1 );
}
if( (W1_IN & (1<<W1_PIN)) == 0 )
b = 0;
_delay_us( 60 - 15 );
//soft_vcc;
hard_vcc;
sei();
return b;
}
uint8_t 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 );
soft_vcc;
return b;
}
uint8_t w1_byte_rd( void )
{
return w1_byte_wr( 0xFF );
}
/*
uint8_t w1_rom_search( uint8_t diff, uint8_t *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 ds1992_read(uint16_t addr, uint8_t* buf, uint8_t len)
{
w1_byte_wr(SKIP_ROM);
w1_byte_wr(0xF0); // read
w1_byte_wr((addr & 0x00FF));
w1_byte_wr((addr & 0xFF00) >> 8);
for (int i=0; i < len; i++)
buf[i] = w1_byte_rd();
}
void ds1992_scratch_write(uint16_t addr, const uint8_t* buf, uint8_t len)
{
w1_byte_wr(SKIP_ROM);
w1_byte_wr(0x0F); // write scratchpad
w1_byte_wr((addr & 0x00FF));
w1_byte_wr((addr & 0xFF00) >> 8);
for (int i=0; i < len; i++)
w1_byte_wr(buf[i]);
}
uint8_t ds1992_scratch_verify(uint16_t addr, const uint8_t* buf, uint8_t len, uint8_t* es_reg_ptr)
{
uint8_t status = 0;
w1_byte_wr(SKIP_ROM);
w1_byte_wr(0xAA); // read scratchpad
// check address bytes
if (w1_byte_rd() != (addr & 0x00FF)) status |= 0x01;
if (w1_byte_rd() != (addr & 0xFF00) >> 8) status |= 0x02;
uint8_t es_reg = w1_byte_rd();
*es_reg_ptr = es_reg;
// check E/S register
if (es_reg & 0x20) // PF: partial byte flag
status |= 0x04;
if (es_reg & 0x40) // OF: overflow flag
status |= 0x08;
if ((es_reg & 0x1F) != (addr & 0x1F) + (len-1))
status |= 0x10;
for (int i=0; i < len; i++)
if (w1_byte_rd() != buf[i])
status |= 0xF0;
return status;
}
void ds1992_scratch_copy(uint16_t addr, uint8_t es_reg)
{
w1_byte_wr(SKIP_ROM);
w1_byte_wr(0x55); // copy scratchpad to memory
w1_byte_wr((addr & 0x00FF));
w1_byte_wr((addr & 0xFF00) >> 8);
w1_byte_wr(es_reg);
while(w1_byte_rd() != 0);
}
void w1_command( uint8_t command, uint8_t *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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