From dd9444a7183411887b736ee66f0daf942786d29a Mon Sep 17 00:00:00 2001
From: "David A. Mellis" <d.mellis@arduino.cc>
Date: Wed, 9 May 2007 15:05:01 +0000
Subject: [PATCH] Activating pull-up resistors on the ATmega168 (in addition to
 the ATmega8).

---
 targets/libraries/Wire/utility/twi.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/targets/libraries/Wire/utility/twi.c b/targets/libraries/Wire/utility/twi.c
index dc90b21f9..2235b0b1c 100644
--- a/targets/libraries/Wire/utility/twi.c
+++ b/targets/libraries/Wire/utility/twi.c
@@ -18,19 +18,19 @@
 */
 
 #include <math.h>
-#include <stdlib.h>
+#include <stdlib.h>
 #include <inttypes.h>
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <avr/signal.h>
 #include <compat/twi.h>
 
-#ifndef cbi
-#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
+#ifndef cbi
+#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
 #endif
-
-#ifndef sbi
-#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
+
+#ifndef sbi
+#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
 #endif
 
 #include "twi.h"
@@ -63,7 +63,7 @@ void twi_init(void)
   // initialize state
   twi_state = TWI_READY;
 
-  #ifdef ATMEGA8
+  #if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__)
     // activate internal pull-ups for twi
     // as per note from atmega8 manual pg167
     sbi(PORTC, 4);
@@ -244,7 +244,7 @@ uint8_t twi_transmit(uint8_t* data, uint8_t length)
  */
 void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int) )
 {
-  twi_onSlaveReceive = function;
+  twi_onSlaveReceive = function;
 }
 
 /* 
@@ -255,7 +255,7 @@ void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int) )
  */
 void twi_attachSlaveTxEvent( void (*function)(void) )
 {
-  twi_onSlaveTransmit = function;
+  twi_onSlaveTransmit = function;
 }
 
 /* 
@@ -267,7 +267,7 @@ void twi_attachSlaveTxEvent( void (*function)(void) )
 void twi_reply(uint8_t ack)
 {
 	// transmit master read ready signal, with or without ack
-	if(ack){
+	if(ack){
 	  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
   }else{
 	  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
@@ -286,7 +286,7 @@ void twi_stop(void)
   TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTO);
 
   // wait for stop condition to be exectued on bus
-  // TWINT is not set after a stop condition!
+  // TWINT is not set after a stop condition!
   while(TWCR & _BV(TWSTO)){
     continue;
   }