i2c fix

1 files changed, 23 insertions, 19 deletions

diff --git a/drivers/avr/i2c_master.c b/drivers/avr/i2c_master.c
index f4a4bb7b0..bcf92153c 100755
--- a/drivers/avr/i2c_master.c
+++ b/drivers/avr/i2c_master.c
@@ -13,32 +13,34 @@
 
 void i2c_init(void)
 {
+  TWSR = 0;     /* no prescaler */
         TWBR = (uint8_t)TWBR_val;
+  //TWBR = 10;
 }
 
 uint8_t i2c_start(uint8_t address)
 {
         // reset TWI control register
-        TWCR = 0;
-        // transmit START condition 
+        //TWCR = 0;
+        // transmit START condition
         TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
         // wait for end of transmission
         while( !(TWCR & (1<<TWINT)) );
-        
+
         // check if the start condition was successfully transmitted
-        if((TWSR & 0xF8) != TW_START){ return 1; }
-        
+        if(((TW_STATUS & 0xF8) != TW_START) && ((TW_STATUS & 0xF8) != TW_REP_START)){ return 1; }
+
         // load slave address into data register
         TWDR = address;
         // start transmission of address
         TWCR = (1<<TWINT) | (1<<TWEN);
         // wait for end of transmission
         while( !(TWCR & (1<<TWINT)) );
-        
+
         // check if the device has acknowledged the READ / WRITE mode
         uint8_t twst = TW_STATUS & 0xF8;
         if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;
-        
+
         return 0;
 }
 
@@ -50,17 +52,17 @@ uint8_t i2c_write(uint8_t data)
         TWCR = (1<<TWINT) | (1<<TWEN);
         // wait for end of transmission
         while( !(TWCR & (1<<TWINT)) );
-        
-        if( (TWSR & 0xF8) != TW_MT_DATA_ACK ){ return 1; }
-        
+
+        if( (TW_STATUS & 0xF8) != TW_MT_DATA_ACK ){ return 1; }
+
         return 0;
 }
 
 uint8_t i2c_read_ack(void)
 {
-        
+
         // start TWI module and acknowledge data after reception
-        TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA); 
+        TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
         // wait for end of transmission
         while( !(TWCR & (1<<TWINT)) );
         // return received data from TWDR
@@ -69,7 +71,7 @@ uint8_t i2c_read_ack(void)
 
 uint8_t i2c_read_nack(void)
 {
-        
+
         // start receiving without acknowledging reception
         TWCR = (1<<TWINT) | (1<<TWEN);
         // wait for end of transmission
@@ -81,29 +83,29 @@ uint8_t i2c_read_nack(void)
 uint8_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length)
 {
         if (i2c_start(address | I2C_WRITE)) return 1;
-        
+
         for (uint16_t i = 0; i < length; i++)
         {
                 if (i2c_write(data[i])) return 1;
         }
-        
+
         i2c_stop();
-        
+
         return 0;
 }
 
 uint8_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length)
 {
         if (i2c_start(address | I2C_READ)) return 1;
-        
+
         for (uint16_t i = 0; i < (length-1); i++)
         {
                 data[i] = i2c_read_ack();
         }
         data[(length-1)] = i2c_read_nack();
-        
+
         i2c_stop();
-        
+
         return 0;
 }
 
@@ -146,4 +148,6 @@ void i2c_stop(void)
 {
         // transmit STOP condition
         TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+  // wait until stop condition is executed and bus released
+  while(TWCR & (1<<TWSTO));
 }