--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/onewire.c	Sat Jun 01 01:38:42 2013 +0800
@@ -0,0 +1,287 @@
+/* 
+Access Dallas 1-Wire Devices with ATMEL AVRs
+Author of the initial code: Peter Dannegger (danni(at)specs.de)
+modified by Martin Thomas (mthomas(at)rhrk.uni-kl.de)
+ 9/2004 - use of delay.h, optional bus configuration at runtime
+10/2009 - additional delay in ow_bit_io for recovery
+ 5/2010 - timing modifcations, additonal config-values and comments,
+          use of atomic.h macros, internal pull-up support
+ 7/2010 - added method to skip recovery time after last bit transfered
+          via ow_command_skip_last_recovery
+*/
+
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include <util/atomic.h>
+
+#include "onewire.h"
+
+#ifdef OW_ONE_BUS
+
+#define OW_GET_IN()   ( OW_IN & (1<<OW_PIN))
+#define OW_OUT_LOW()  ( OW_OUT &= (~(1 << OW_PIN)) )
+#define OW_OUT_HIGH() ( OW_OUT |= (1 << OW_PIN) )
+#define OW_DIR_IN()   ( OW_DDR &= (~(1 << OW_PIN )) )
+#define OW_DIR_OUT()  ( OW_DDR |= (1 << OW_PIN) )
+
+#else
+
+/* set bus-config with ow_set_bus() */
+uint8_t OW_PIN_MASK; 
+volatile uint8_t* OW_IN;
+volatile uint8_t* OW_OUT;
+volatile uint8_t* OW_DDR;
+
+#define OW_GET_IN()   ( *OW_IN & OW_PIN_MASK )
+#define OW_OUT_LOW()  ( *OW_OUT &= (uint8_t) ~OW_PIN_MASK )
+#define OW_OUT_HIGH() ( *OW_OUT |= (uint8_t)  OW_PIN_MASK )
+#define OW_DIR_IN()   ( *OW_DDR &= (uint8_t) ~OW_PIN_MASK )
+#define OW_DIR_OUT()  ( *OW_DDR |= (uint8_t)  OW_PIN_MASK )
+
+void ow_set_bus(volatile uint8_t* in,
+	volatile uint8_t* out,
+	volatile uint8_t* ddr,
+	uint8_t pin)
+{
+	OW_DDR=ddr;
+	OW_OUT=out;
+	OW_IN=in;
+	OW_PIN_MASK = (1 << pin);
+	ow_reset();
+}
+
+#endif
+
+uint8_t ow_input_pin_state()
+{
+	return OW_GET_IN();
+}
+
+void ow_parasite_enable(void)
+{
+	OW_OUT_HIGH();
+	OW_DIR_OUT();
+}
+
+void ow_parasite_disable(void)
+{
+	OW_DIR_IN();
+#if (!OW_USE_INTERNAL_PULLUP)
+	OW_OUT_LOW();
+#endif
+}
+
+
+uint8_t ow_reset(void)
+{
+	uint8_t err;
+	
+	OW_OUT_LOW();
+	OW_DIR_OUT();            // pull OW-Pin low for 480us
+	_delay_us(480);
+
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+		// set Pin as input - wait for clients to pull low
+		OW_DIR_IN(); // input
+#if OW_USE_INTERNAL_PULLUP
+		OW_OUT_HIGH();
+#endif
+	
+		_delay_us(64);       // was 66
+		err = OW_GET_IN();   // no presence detect
+		                     // if err!=0: nobody pulled to low, still high
+	}
+	
+	// after a delay the clients should release the line
+	// and input-pin gets back to high by pull-up-resistor
+	_delay_us(480 - 64);       // was 480-66
+	if( OW_GET_IN() == 0 ) {
+		err = 1;             // short circuit, expected low but got high
+	}
+	
+	return err;
+}
+
+
+/* Timing issue when using runtime-bus-selection (!OW_ONE_BUS):
+   The master should sample at the end of the 15-slot after initiating
+   the read-time-slot. The variable bus-settings need more
+   cycles than the constant ones so the delays had to be shortened 
+   to achive a 15uS overall delay 
+   Setting/clearing a bit in I/O Register needs 1 cyle in OW_ONE_BUS
+   but around 14 cyles in configureable bus (us-Delay is 4 cyles per uS) */
+static uint8_t ow_bit_io_intern( uint8_t b, uint8_t with_parasite_enable )
+{
+	ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
+#if OW_USE_INTERNAL_PULLUP
+		OW_OUT_LOW();
+#endif
+		OW_DIR_OUT();    // drive bus low
+		_delay_us(2);    // T_INT > 1usec accoding to timing-diagramm
+		if ( b ) {
+			OW_DIR_IN(); // to write "1" release bus, resistor pulls high
+#if OW_USE_INTERNAL_PULLUP
+			OW_OUT_HIGH();
+#endif
+		}
+
+		// "Output data from the DS18B20 is valid for 15usec after the falling
+		// edge that initiated the read time slot. Therefore, the master must 
+		// release the bus and then sample the bus state within 15ussec from 
+		// the start of the slot."
+		_delay_us(15-2-OW_CONF_DELAYOFFSET);
+		
+		if( OW_GET_IN() == 0 ) {
+			b = 0;  // sample at end of read-timeslot
+		}
+	
+		_delay_us(60-15-2+OW_CONF_DELAYOFFSET);
+#if OW_USE_INTERNAL_PULLUP
+		OW_OUT_HIGH();
+#endif
+		OW_DIR_IN();
+	
+		if ( with_parasite_enable ) {
+			ow_parasite_enable();
+		}
+	
+	} /* ATOMIC_BLOCK */
+
+	_delay_us(OW_RECOVERY_TIME); // may be increased for longer wires
+
+	return b;
+}
+
+uint8_t ow_bit_io( uint8_t b )
+{
+	return ow_bit_io_intern( b & 1, 0 );
+}
+
+uint8_t ow_byte_wr( uint8_t b )
+{
+	uint8_t i = 8, j;
+	
+	do {
+		j = ow_bit_io( b & 1 );
+		b >>= 1;
+		if( j ) {
+			b |= 0x80;
+		}
+	} while( --i );
+	
+	return b;
+}
+
+uint8_t ow_byte_wr_with_parasite_enable( uint8_t b )
+{
+	uint8_t i = 8, j;
+	
+	do {
+		if ( i != 1 ) {
+			j = ow_bit_io_intern( b & 1, 0 );
+		} else {
+			j = ow_bit_io_intern( b & 1, 1 );
+		}
+		b >>= 1;
+		if( j ) {
+			b |= 0x80;
+		}
+	} while( --i );
+	
+	return b;
+}
+
+
+uint8_t ow_byte_rd( void )
+{
+	// read by sending only "1"s, so bus gets released
+	// after the init low-pulse in every slot
+	return ow_byte_wr( 0xFF ); 
+}
+
+
+uint8_t ow_rom_search( uint8_t diff, uint8_t *id )
+{
+	uint8_t i, j, next_diff;
+	uint8_t b;
+	
+	if( ow_reset() ) {
+		return OW_PRESENCE_ERR;         // error, no device found <--- early exit!
+	}
+	
+	ow_byte_wr( OW_SEARCH_ROM );        // ROM search command
+	next_diff = OW_LAST_DEVICE;         // unchanged on last device
+	
+	i = OW_ROMCODE_SIZE * 8;            // 8 bytes
+	
+	do {
+		j = 8;                          // 8 bits
+		do {
+			b = ow_bit_io( 1 );         // read bit
+			if( ow_bit_io( 1 ) ) {      // read complement bit
+				if( b ) {               // 0b11
+					return OW_DATA_ERR; // data error <--- early exit!
+				}
+			}
+			else {
+				if( !b ) {              // 0b00 = 2 devices
+					if( diff > i || ((*id & 1) && diff != i) ) {
+						b = 1;          // now 1
+						next_diff = i;  // next pass 0
+					}
+				}
+			}
+			ow_bit_io( b );             // write bit
+			*id >>= 1;
+			if( b ) {
+				*id |= 0x80;            // store bit
+			}
+			
+			i--;
+			
+		} while( --j );
+		
+		id++;                           // next byte
+	
+	} while( i );
+	
+	return next_diff;                   // to continue search
+}
+
+
+static void ow_command_intern( uint8_t command, uint8_t *id, uint8_t with_parasite_enable )
+{
+	uint8_t i;
+
+	ow_reset();
+
+	if( id ) {
+		ow_byte_wr( OW_MATCH_ROM );     // to a single device
+		i = OW_ROMCODE_SIZE;
+		do {
+			ow_byte_wr( *id );
+			id++;
+		} while( --i );
+	} 
+	else {
+		ow_byte_wr( OW_SKIP_ROM );      // to all devices
+	}
+	
+	if ( with_parasite_enable  ) {
+		ow_byte_wr_with_parasite_enable( command );
+	} else {
+		ow_byte_wr( command );
+	}
+}
+
+void ow_command( uint8_t command, uint8_t *id )
+{
+	ow_command_intern( command, id, 0);
+}
+
+void ow_command_with_parasite_enable( uint8_t command, uint8_t *id )
+{
+	ow_command_intern( command, id, 1 );
+}
+