-#ifndef _I2CMASTER_H\r
-#define _I2CMASTER_H 1\r
-/************************************************************************* \r
-* Title: C include file for the I2C master interface \r
-* (i2cmaster.S or twimaster.c)\r
-* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury\r
-* File: $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $\r
-* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3\r
-* Target: any AVR device\r
-* Usage: see Doxygen manual\r
-**************************************************************************/\r
-\r
-#ifdef DOXYGEN\r
-/**\r
- @defgroup pfleury_ic2master I2C Master library\r
- @code #include <i2cmaster.h> @endcode\r
- \r
- @brief I2C (TWI) Master Software Library\r
-\r
- Basic routines for communicating with I2C slave devices. This single master \r
- implementation is limited to one bus master on the I2C bus. \r
-\r
- This I2c library is implemented as a compact assembler software implementation of the I2C protocol \r
- which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c).\r
- Since the API for these two implementations is exactly the same, an application can be linked either against the\r
- software I2C implementation or the hardware I2C implementation.\r
-\r
- Use 4.7k pull-up resistor on the SDA and SCL pin.\r
- \r
- Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module \r
- i2cmaster.S to your target when using the software I2C implementation ! \r
- \r
- Adjust the CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion.\r
-\r
- @note \r
- The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted \r
- to GNU assembler and AVR-GCC C call interface.\r
- Replaced the incorrect quarter period delays found in AVR300 with \r
- half period delays. \r
- \r
- @author Peter Fleury pfleury@gmx.ch http://jump.to/fleury\r
-\r
- @par API Usage Example\r
- The following code shows typical usage of this library, see example test_i2cmaster.c\r
-\r
- @code\r
-\r
- #include <i2cmaster.h>\r
-\r
-\r
- #define Dev24C02 0xA2 // device address of EEPROM 24C02, see datasheet\r
-\r
- int main(void)\r
- {\r
- unsigned char ret;\r
-\r
- i2c_init(); // initialize I2C library\r
-\r
- // write 0x75 to EEPROM address 5 (Byte Write) \r
- i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode\r
- i2c_write(0x05); // write address = 5\r
- i2c_write(0x75); // write value 0x75 to EEPROM\r
- i2c_stop(); // set stop conditon = release bus\r
-\r
-\r
- // read previously written value back from EEPROM address 5 \r
- i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode\r
-\r
- i2c_write(0x05); // write address = 5\r
- i2c_rep_start(Dev24C02+I2C_READ); // set device address and read mode\r
-\r
- ret = i2c_readNak(); // read one byte from EEPROM\r
- i2c_stop();\r
-\r
- for(;;);\r
- }\r
- @endcode\r
-\r
-*/\r
-#endif /* DOXYGEN */\r
-\r
-/**@{*/\r
-\r
-#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304\r
-#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"\r
-#endif\r
-\r
-#include <avr/io.h>\r
-\r
-/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */\r
-#define I2C_READ 1\r
-\r
-/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */\r
-#define I2C_WRITE 0\r
-\r
-\r
-/**\r
- @brief initialize the I2C master interace. Need to be called only once \r
- @param void\r
- @return none\r
- */\r
-extern void i2c_init(void);\r
-\r
-\r
-/** \r
- @brief Terminates the data transfer and releases the I2C bus \r
- @param void\r
- @return none\r
- */\r
-extern void i2c_stop(void);\r
-\r
-\r
-/** \r
- @brief Issues a start condition and sends address and transfer direction \r
- \r
- @param addr address and transfer direction of I2C device\r
- @retval 0 device accessible \r
- @retval 1 failed to access device \r
- */\r
-extern unsigned char i2c_start(unsigned char addr);\r
-\r
-\r
-/**\r
- @brief Issues a repeated start condition and sends address and transfer direction \r
-\r
- @param addr address and transfer direction of I2C device\r
- @retval 0 device accessible\r
- @retval 1 failed to access device\r
- */\r
-extern unsigned char i2c_rep_start(unsigned char addr);\r
-\r
-\r
-/**\r
- @brief Issues a start condition and sends address and transfer direction \r
- \r
- If device is busy, use ack polling to wait until device ready \r
- @param addr address and transfer direction of I2C device\r
- @return none\r
- */\r
-extern void i2c_start_wait(unsigned char addr);\r
-\r
- \r
-/**\r
- @brief Send one byte to I2C device\r
- @param data byte to be transfered\r
- @retval 0 write successful\r
- @retval 1 write failed\r
- */\r
-extern unsigned char i2c_write(unsigned char data);\r
-\r
-\r
-/**\r
- @brief read one byte from the I2C device, request more data from device \r
- @return byte read from I2C device\r
- */\r
-extern unsigned char i2c_readAck(void);\r
-\r
-/**\r
- @brief read one byte from the I2C device, read is followed by a stop condition \r
- @return byte read from I2C device\r
- */\r
-extern unsigned char i2c_readNak(void);\r
-\r
-/** \r
- @brief read one byte from the I2C device\r
- \r
- Implemented as a macro, which calls either i2c_readAck or i2c_readNak\r
- \r
- @param ack 1 send ack, request more data from device<br>\r
- 0 send nak, read is followed by a stop condition \r
- @return byte read from I2C device\r
- */\r
-extern unsigned char i2c_read(unsigned char ack);\r
-#define i2c_read(ack) (ack) ? i2c_readAck() : i2c_readNak(); \r
-\r
-\r
-/**@}*/\r
-#endif\r
+#ifndef _I2CMASTER_H
+#define _I2CMASTER_H 1
+/*************************************************************************
+* Title: C include file for the I2C master interface
+* (i2cmaster.S or twimaster.c)
+* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
+* File: $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $
+* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
+* Target: any AVR device
+* Usage: see Doxygen manual
+**************************************************************************/
+
+#ifdef DOXYGEN
+/**
+ @defgroup pfleury_ic2master I2C Master library
+ @code #include <i2cmaster.h> @endcode
+
+ @brief I2C (TWI) Master Software Library
+
+ Basic routines for communicating with I2C slave devices. This single master
+ implementation is limited to one bus master on the I2C bus.
+
+ This I2c library is implemented as a compact assembler software implementation of the I2C protocol
+ which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c).
+ Since the API for these two implementations is exactly the same, an application can be linked either against the
+ software I2C implementation or the hardware I2C implementation.
+
+ Use 4.7k pull-up resistor on the SDA and SCL pin.
+
+ Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module
+ i2cmaster.S to your target when using the software I2C implementation !
+
+ Adjust the CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion.
+
+ @note
+ The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted
+ to GNU assembler and AVR-GCC C call interface.
+ Replaced the incorrect quarter period delays found in AVR300 with
+ half period delays.
+
+ @author Peter Fleury pfleury@gmx.ch http://jump.to/fleury
+
+ @par API Usage Example
+ The following code shows typical usage of this library, see example test_i2cmaster.c
+
+ @code
+
+ #include <i2cmaster.h>
+
+
+ #define Dev24C02 0xA2 // device address of EEPROM 24C02, see datasheet
+
+ int main(void)
+ {
+ unsigned char ret;
+
+ i2c_init(); // initialize I2C library
+
+ // write 0x75 to EEPROM address 5 (Byte Write)
+ i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode
+ i2c_write(0x05); // write address = 5
+ i2c_write(0x75); // write value 0x75 to EEPROM
+ i2c_stop(); // set stop conditon = release bus
+
+
+ // read previously written value back from EEPROM address 5
+ i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode
+
+ i2c_write(0x05); // write address = 5
+ i2c_rep_start(Dev24C02+I2C_READ); // set device address and read mode
+
+ ret = i2c_readNak(); // read one byte from EEPROM
+ i2c_stop();
+
+ for(;;);
+ }
+ @endcode
+
+*/
+#endif /* DOXYGEN */
+
+/**@{*/
+
+#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
+#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
+#endif
+
+#include <avr/io.h>
+
+/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */
+#define I2C_READ 1
+
+/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */
+#define I2C_WRITE 0
+
+
+/**
+ @brief initialize the I2C master interace. Need to be called only once
+ @param void
+ @return none
+ */
+extern void i2c_init(void);
+
+
+/**
+ @brief Terminates the data transfer and releases the I2C bus
+ @param void
+ @return none
+ */
+extern void i2c_stop(void);
+
+
+/**
+ @brief Issues a start condition and sends address and transfer direction
+
+ @param addr address and transfer direction of I2C device
+ @retval 0 device accessible
+ @retval 1 failed to access device
+ */
+extern unsigned char i2c_start(unsigned char addr);
+
+
+/**
+ @brief Issues a repeated start condition and sends address and transfer direction
+
+ @param addr address and transfer direction of I2C device
+ @retval 0 device accessible
+ @retval 1 failed to access device
+ */
+extern unsigned char i2c_rep_start(unsigned char addr);
+
+
+/**
+ @brief Issues a start condition and sends address and transfer direction
+
+ If device is busy, use ack polling to wait until device ready
+ @param addr address and transfer direction of I2C device
+ @return none
+ */
+extern void i2c_start_wait(unsigned char addr);
+
+
+/**
+ @brief Send one byte to I2C device
+ @param data byte to be transfered
+ @retval 0 write successful
+ @retval 1 write failed
+ */
+extern unsigned char i2c_write(unsigned char data);
+
+
+/**
+ @brief read one byte from the I2C device, request more data from device
+ @return byte read from I2C device
+ */
+extern unsigned char i2c_readAck(void);
+
+/**
+ @brief read one byte from the I2C device, read is followed by a stop condition
+ @return byte read from I2C device
+ */
+extern unsigned char i2c_readNak(void);
+
+/**
+ @brief read one byte from the I2C device
+
+ Implemented as a macro, which calls either i2c_readAck or i2c_readNak
+
+ @param ack 1 send ack, request more data from device<br>
+ 0 send nak, read is followed by a stop condition
+ @return byte read from I2C device
+ */
+extern unsigned char i2c_read(unsigned char ack);
+#define i2c_read(ack) (ack) ? i2c_readAck() : i2c_readNak();
+
+
+/**@}*/
+#endif
-/*************************************************************************\r
-* Title: I2C master library using hardware TWI interface\r
-* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury\r
-* File: $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $\r
-* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3\r
-* Target: any AVR device with hardware TWI \r
-* Usage: API compatible with I2C Software Library i2cmaster.h\r
-**************************************************************************/\r
-#include <inttypes.h>\r
-#include <compat/twi.h>\r
-\r
-#include <i2cmaster.h>\r
-\r
-\r
-/* define CPU frequency in Mhz here if not defined in Makefile */\r
-#ifndef F_CPU\r
-#define F_CPU 4000000UL\r
-#endif\r
-\r
-/* I2C clock in Hz */\r
-#define SCL_CLOCK 100000L\r
-\r
-\r
-/*************************************************************************\r
- Initialization of the I2C bus interface. Need to be called only once\r
-*************************************************************************/\r
-void i2c_init(void)\r
-{\r
- /* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */\r
- \r
- TWSR = 0; /* no prescaler */\r
- TWBR = ((F_CPU/SCL_CLOCK)-16)/2; /* must be > 10 for stable operation */\r
-\r
-}/* i2c_init */\r
-\r
-\r
-/************************************************************************* \r
- Issues a start condition and sends address and transfer direction.\r
- return 0 = device accessible, 1= failed to access device\r
-*************************************************************************/\r
-unsigned char i2c_start(unsigned char address)\r
-{\r
- uint8_t twst;\r
-\r
- // send START condition\r
- TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);\r
-\r
- // wait until transmission completed\r
- while(!(TWCR & (1<<TWINT)));\r
-\r
- // check value of TWI Status Register. Mask prescaler bits.\r
- twst = TW_STATUS & 0xF8;\r
- if ( (twst != TW_START) && (twst != TW_REP_START)) return 1;\r
-\r
- // send device address\r
- TWDR = address;\r
- TWCR = (1<<TWINT) | (1<<TWEN);\r
-\r
- // wail until transmission completed and ACK/NACK has been received\r
- while(!(TWCR & (1<<TWINT)));\r
-\r
- // check value of TWI Status Register. Mask prescaler bits.\r
- twst = TW_STATUS & 0xF8;\r
- if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;\r
-\r
- return 0;\r
-\r
-}/* i2c_start */\r
-\r
-\r
-/*************************************************************************\r
- Issues a start condition and sends address and transfer direction.\r
- If device is busy, use ack polling to wait until device is ready\r
- \r
- Input: address and transfer direction of I2C device\r
-*************************************************************************/\r
-void i2c_start_wait(unsigned char address)\r
-{\r
- uint8_t twst;\r
-\r
-\r
- while ( 1 )\r
- {\r
- // send START condition\r
- TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);\r
- \r
- // wait until transmission completed\r
- while(!(TWCR & (1<<TWINT)));\r
- \r
- // check value of TWI Status Register. Mask prescaler bits.\r
- twst = TW_STATUS & 0xF8;\r
- if ( (twst != TW_START) && (twst != TW_REP_START)) continue;\r
- \r
- // send device address\r
- TWDR = address;\r
- TWCR = (1<<TWINT) | (1<<TWEN);\r
- \r
- // wail until transmission completed\r
- while(!(TWCR & (1<<TWINT)));\r
- \r
- // check value of TWI Status Register. Mask prescaler bits.\r
- twst = TW_STATUS & 0xF8;\r
- if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) ) \r
- { \r
- /* device busy, send stop condition to terminate write operation */\r
- TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);\r
- \r
- // wait until stop condition is executed and bus released\r
- while(TWCR & (1<<TWSTO));\r
- \r
- continue;\r
- }\r
- //if( twst != TW_MT_SLA_ACK) return 1;\r
- break;\r
- }\r
-\r
-}/* i2c_start_wait */\r
-\r
-\r
-/*************************************************************************\r
- Issues a repeated start condition and sends address and transfer direction \r
-\r
- Input: address and transfer direction of I2C device\r
- \r
- Return: 0 device accessible\r
- 1 failed to access device\r
-*************************************************************************/\r
-unsigned char i2c_rep_start(unsigned char address)\r
-{\r
- return i2c_start( address );\r
-\r
-}/* i2c_rep_start */\r
-\r
-\r
-/*************************************************************************\r
- Terminates the data transfer and releases the I2C bus\r
-*************************************************************************/\r
-void i2c_stop(void)\r
-{\r
- /* send stop condition */\r
- TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);\r
- \r
- // wait until stop condition is executed and bus released\r
- while(TWCR & (1<<TWSTO));\r
-\r
-}/* i2c_stop */\r
-\r
-\r
-/*************************************************************************\r
- Send one byte to I2C device\r
- \r
- Input: byte to be transfered\r
- Return: 0 write successful \r
- 1 write failed\r
-*************************************************************************/\r
-unsigned char i2c_write( unsigned char data )\r
-{ \r
- uint8_t twst;\r
- \r
- // send data to the previously addressed device\r
- TWDR = data;\r
- TWCR = (1<<TWINT) | (1<<TWEN);\r
-\r
- // wait until transmission completed\r
- while(!(TWCR & (1<<TWINT)));\r
-\r
- // check value of TWI Status Register. Mask prescaler bits\r
- twst = TW_STATUS & 0xF8;\r
- if( twst != TW_MT_DATA_ACK) return 1;\r
- return 0;\r
-\r
-}/* i2c_write */\r
-\r
-\r
-/*************************************************************************\r
- Read one byte from the I2C device, request more data from device \r
- \r
- Return: byte read from I2C device\r
-*************************************************************************/\r
-unsigned char i2c_readAck(void)\r
-{\r
- TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);\r
- while(!(TWCR & (1<<TWINT))); \r
-\r
- return TWDR;\r
-\r
-}/* i2c_readAck */\r
-\r
-\r
-/*************************************************************************\r
- Read one byte from the I2C device, read is followed by a stop condition \r
- \r
- Return: byte read from I2C device\r
-*************************************************************************/\r
-unsigned char i2c_readNak(void)\r
-{\r
- TWCR = (1<<TWINT) | (1<<TWEN);\r
- while(!(TWCR & (1<<TWINT)));\r
- \r
- return TWDR;\r
-\r
-}/* i2c_readNak */\r
+/*************************************************************************
+* Title: I2C master library using hardware TWI interface
+* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
+* File: $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $
+* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
+* Target: any AVR device with hardware TWI
+* Usage: API compatible with I2C Software Library i2cmaster.h
+**************************************************************************/
+#include <inttypes.h>
+#include <compat/twi.h>
+
+#include <i2cmaster.h>
+
+
+/* define CPU frequency in Mhz here if not defined in Makefile */
+#ifndef F_CPU
+#define F_CPU 4000000UL
+#endif
+
+/* I2C clock in Hz */
+#define SCL_CLOCK 100000L
+
+
+/*************************************************************************
+ Initialization of the I2C bus interface. Need to be called only once
+*************************************************************************/
+void i2c_init(void)
+{
+ /* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */
+
+ TWSR = 0; /* no prescaler */
+ TWBR = ((F_CPU/SCL_CLOCK)-16)/2; /* must be > 10 for stable operation */
+
+}/* i2c_init */
+
+
+/*************************************************************************
+ Issues a start condition and sends address and transfer direction.
+ return 0 = device accessible, 1= failed to access device
+*************************************************************************/
+unsigned char i2c_start(unsigned char address)
+{
+ uint8_t twst;
+
+ // send START condition
+ TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
+
+ // wait until transmission completed
+ while(!(TWCR & (1<<TWINT)));
+
+ // check value of TWI Status Register. Mask prescaler bits.
+ twst = TW_STATUS & 0xF8;
+ if ( (twst != TW_START) && (twst != TW_REP_START)) return 1;
+
+ // send device address
+ TWDR = address;
+ TWCR = (1<<TWINT) | (1<<TWEN);
+
+ // wail until transmission completed and ACK/NACK has been received
+ while(!(TWCR & (1<<TWINT)));
+
+ // check value of TWI Status Register. Mask prescaler bits.
+ twst = TW_STATUS & 0xF8;
+ if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;
+
+ return 0;
+
+}/* i2c_start */
+
+
+/*************************************************************************
+ Issues a start condition and sends address and transfer direction.
+ If device is busy, use ack polling to wait until device is ready
+
+ Input: address and transfer direction of I2C device
+*************************************************************************/
+void i2c_start_wait(unsigned char address)
+{
+ uint8_t twst;
+
+
+ while ( 1 )
+ {
+ // send START condition
+ TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
+
+ // wait until transmission completed
+ while(!(TWCR & (1<<TWINT)));
+
+ // check value of TWI Status Register. Mask prescaler bits.
+ twst = TW_STATUS & 0xF8;
+ if ( (twst != TW_START) && (twst != TW_REP_START)) continue;
+
+ // send device address
+ TWDR = address;
+ TWCR = (1<<TWINT) | (1<<TWEN);
+
+ // wail until transmission completed
+ while(!(TWCR & (1<<TWINT)));
+
+ // check value of TWI Status Register. Mask prescaler bits.
+ twst = TW_STATUS & 0xF8;
+ if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) )
+ {
+ /* device busy, send stop condition to terminate write operation */
+ TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+
+ // wait until stop condition is executed and bus released
+ while(TWCR & (1<<TWSTO));
+
+ continue;
+ }
+ //if( twst != TW_MT_SLA_ACK) return 1;
+ break;
+ }
+
+}/* i2c_start_wait */
+
+
+/*************************************************************************
+ Issues a repeated start condition and sends address and transfer direction
+
+ Input: address and transfer direction of I2C device
+
+ Return: 0 device accessible
+ 1 failed to access device
+*************************************************************************/
+unsigned char i2c_rep_start(unsigned char address)
+{
+ return i2c_start( address );
+
+}/* i2c_rep_start */
+
+
+/*************************************************************************
+ Terminates the data transfer and releases the I2C bus
+*************************************************************************/
+void i2c_stop(void)
+{
+ /* send stop condition */
+ TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+
+ // wait until stop condition is executed and bus released
+ while(TWCR & (1<<TWSTO));
+
+}/* i2c_stop */
+
+
+/*************************************************************************
+ Send one byte to I2C device
+
+ Input: byte to be transfered
+ Return: 0 write successful
+ 1 write failed
+*************************************************************************/
+unsigned char i2c_write( unsigned char data )
+{
+ uint8_t twst;
+
+ // send data to the previously addressed device
+ TWDR = data;
+ TWCR = (1<<TWINT) | (1<<TWEN);
+
+ // wait until transmission completed
+ while(!(TWCR & (1<<TWINT)));
+
+ // check value of TWI Status Register. Mask prescaler bits
+ twst = TW_STATUS & 0xF8;
+ if( twst != TW_MT_DATA_ACK) return 1;
+ return 0;
+
+}/* i2c_write */
+
+
+/*************************************************************************
+ Read one byte from the I2C device, request more data from device
+
+ Return: byte read from I2C device
+*************************************************************************/
+unsigned char i2c_readAck(void)
+{
+ TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
+ while(!(TWCR & (1<<TWINT)));
+
+ return TWDR;
+
+}/* i2c_readAck */
+
+
+/*************************************************************************
+ Read one byte from the I2C device, read is followed by a stop condition
+
+ Return: byte read from I2C device
+*************************************************************************/
+unsigned char i2c_readNak(void)
+{
+ TWCR = (1<<TWINT) | (1<<TWEN);
+ while(!(TWCR & (1<<TWINT)));
+
+ return TWDR;
+
+}/* i2c_readNak */
projects / max / tmk_keyboard.git / commitdiff