i2c fix

[qmk_firmware.git] / drivers / avr / i2c_master.c

diff --git a/drivers/avr/i2c_master.c b/drivers/avr/i2c_master.c
index f4a4bb7b0be474e9d486e5382d94042778ac2606..bcf92153c5c89399e4a05e51f67f1bcdaa56e90f 100755 (executable)
--- 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));
 }