X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=drivers%2Favr%2Fi2c_master.c;h=bcf92153c5c89399e4a05e51f67f1bcdaa56e90f;hb=682555faac8a67deff5688b956165cd1c39389cb;hp=f4a4bb7b0be474e9d486e5382d94042778ac2606;hpb=6dc215cd679d54ca2ab985c21c9bb299aca74b01;p=qmk_firmware.git

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));
 }