From e7eeeb0d4e825a175c67cd1c0256c91362517ebb Mon Sep 17 00:00:00 2001
From: neoraider <devnull@localhost>
Date: Wed, 18 Apr 2007 23:00:05 +0000
Subject: Entfernungssensoren in Ordnung gebracht, Hindernisumfahrung
 implementiert.

---
 i2c.cpp | 78 +++++++++++++++++++++++++++++++++++------------------------------
 1 file changed, 42 insertions(+), 36 deletions(-)

(limited to 'i2c.cpp')

diff --git a/i2c.cpp b/i2c.cpp
index 61450fa..39b6b28 100644
--- a/i2c.cpp
+++ b/i2c.cpp
@@ -1,4 +1,5 @@
 #include "i2c.h"
+#include "avr.h"
 
 #include <util/twi.h>
 
@@ -9,41 +10,43 @@ static void I2CStop();
 
 
 static bool I2CStartSend(uint8_t addr) {
-  TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWSTA);
-  
-  while(!(TWCR & (1<<TWINT)));
-      
-  if (TW_STATUS != TW_START) return false;
-  
-  TWDR = (addr&0xFE);
-  TWCR = (1<<TWEN)|(1<<TWINT);
-  
-  while(!(TWCR & (1<<TWINT)));
-  
-  if(TW_STATUS == TW_MT_SLA_ACK)
-    return true;
-  
-  I2CStop();
-  return false;
+  while(true) {
+    TWCR |= (1<<TWINT)|(1<<TWSTA);
+    
+    while(!(TWCR & (1<<TWINT)));
+    
+    if(TW_STATUS != TW_START && TW_STATUS != TW_REP_START) continue;
+    
+    TWDR = (addr&0xFE);
+    TWCR = (1<<TWEN)|(1<<TWINT);
+    
+    while(!(TWCR & (1<<TWINT)));
+    
+    if(TW_STATUS == TW_MT_SLA_ACK)
+      return true;
+    
+    I2CStop();
+  }
 }
 
 static bool I2CStartRecv(uint8_t addr) {
-  TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWSTA);
-  
-  while(!(TWCR & (1<<TWINT)));
-      
-  if (TW_STATUS != TW_START) return false;
-  
-  TWDR = (addr|1);
-  TWCR = (1<<TWEN)|(1<<TWINT);
-  
-  while(!(TWCR & (1<<TWINT)));
-  
-  if(TW_STATUS == TW_MR_SLA_ACK)
-    return true;
-  
-  I2CStop();
-  return false;
+  while(true) {
+    TWCR |= (1<<TWINT)|(1<<TWSTA);
+    
+    while(!(TWCR & (1<<TWINT)));
+        
+    if(TW_STATUS != TW_START && TW_STATUS != TW_REP_START) continue;
+    
+    TWDR = (addr|1);
+    TWCR |= (1<<TWINT);
+    
+    while(!(TWCR & (1<<TWINT)));
+    
+    if(TW_STATUS == TW_MR_SLA_ACK)
+      return true;
+    
+    I2CStop();
+  }
 }
 
 static void I2CStop() {
@@ -83,7 +86,7 @@ bool I2CSend(uint8_t addr, uint8_t *data, int length) {
     TWCR = (1<<TWEN)|(1<<TWINT);
     while(!(TWCR & (1<<TWINT)));
     
-    if(TW_STATUS != TW_MT_DATA_ACK) {
+    if(TW_STATUS != TW_MT_DATA_ACK && i < length-1) {
       I2CStop();
       return false;
     }
@@ -96,6 +99,8 @@ bool I2CSend(uint8_t addr, uint8_t *data, int length) {
 bool I2CRecvByte(uint8_t addr, uint8_t *data) {
   if(!I2CStartRecv(addr)) return false;
   
+  TWCR = (1<<TWEN)|(1<<TWINT);
+  
   while(!(TWCR & (1<<TWINT)));
   
   if(TW_STATUS != TW_MR_DATA_ACK && TW_STATUS != TW_MR_DATA_NACK) {
@@ -107,23 +112,24 @@ bool I2CRecvByte(uint8_t addr, uint8_t *data) {
   TWCR = (1<<TWEN)|(1<<TWINT);
   
   I2CStop();
+  
   return true;
 }
 
 int I2CRecv(uint8_t addr, uint8_t *data, int length) {
   if(!I2CStartRecv(addr)) return -1;
   
+  TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA);
+  
   for(int i = 0; i < length-1; i++) {
     while(!(TWCR & (1<<TWINT)));
     
     switch(TW_STATUS) {
       case TW_MR_DATA_ACK:
         data[i] = TWDR;
-        TWCR = (1<<TWEN)|(1<<TWINT)|(1<<TWEA);
         break;
       case TW_MR_DATA_NACK:
         data[i] = TWDR;
-        TWCR = (1<<TWEN)|(1<<TWINT);
         I2CStop();
         return i+1;
       default:
@@ -132,13 +138,13 @@ int I2CRecv(uint8_t addr, uint8_t *data, int length) {
     }
   }
   
+  TWCR = (1<<TWEN)|(1<<TWINT);
   while(!(TWCR & (1<<TWINT)));
   
   switch(TW_STATUS) {
     case TW_MR_DATA_ACK:
     case TW_MR_DATA_NACK:
       data[length-1] = TWDR;
-      TWCR = (1<<TWEN)|(1<<TWINT);
       I2CStop();
       return length;
   }
-- 
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