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#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 |
**************************************************************************/ |
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#ifdef DOXYGEN |
/** |
@defgroup pfleury_ic2master I2C Master library |
@code #include <i2cmaster.h> @endcode |
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@brief I2C (TWI) Master Software Library |
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Basic routines for communicating with I2C slave devices. This single master |
implementation is limited to one bus master on the I2C bus. |
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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. |
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Use 4.7k pull-up resistor on the SDA and SCL pin. |
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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 ! |
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Adjust the CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion. |
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@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. |
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@author Peter Fleury pfleury@gmx.ch http://jump.to/fleury |
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@par API Usage Example |
The following code shows typical usage of this library, see example test_i2cmaster.c |
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@code |
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#include <i2cmaster.h> |
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#define Dev24C02 0xA2 // device address of EEPROM 24C02, see datasheet |
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int main(void) |
{ |
unsigned char ret; |
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i2c_init(); // initialize I2C library |
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// 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 |
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// read previously written value back from EEPROM address 5 |
i2c_start_wait(Dev24C02+I2C_WRITE); // set device address and write mode |
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i2c_write(0x05); // write address = 5 |
i2c_rep_start(Dev24C02+I2C_READ); // set device address and read mode |
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ret = i2c_readNak(); // read one byte from EEPROM |
i2c_stop(); |
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for(;;); |
} |
@endcode |
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*/ |
#endif /* DOXYGEN */ |
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/**@{*/ |
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#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304 |
#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !" |
#endif |
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#include <avr/io.h> |
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/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */ |
#define I2C_READ 1 |
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/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */ |
#define I2C_WRITE 0 |
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/** |
@brief initialize the I2C master interace. Need to be called only once |
@param void |
@return none |
*/ |
extern void i2c_init(void); |
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/** |
@brief Terminates the data transfer and releases the I2C bus |
@param void |
@return none |
*/ |
extern void i2c_stop(void); |
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/** |
@brief Issues a start condition and sends address and transfer direction |
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@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); |
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/** |
@brief Issues a repeated start condition and sends address and transfer direction |
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@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); |
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/** |
@brief Issues a start condition and sends address and transfer direction |
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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); |
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/** |
@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); |
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/** |
@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); |
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/** |
@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); |
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/** |
@brief read one byte from the I2C device |
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Implemented as a macro, which calls either i2c_readAck or i2c_readNak |
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@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(); |
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/**@}*/ |
#endif |
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