1 files changed, 130 insertions, 0 deletions
diff --git a/avr/1wire.c b/avr/1wire.c
new file mode 100644
index 0000000..237abb9
--- /dev/null
+++ b/avr/1wire.c
@@ -0,0 +1,130 @@
+/************************************************************************/
+/*									*/
+/*			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 );
+}