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| /**************************************************************************** |
| Title : C file for the I2C FUNCTIONS library (i2c.c) |
| Author: Chris efstathiou hendrix@otenet.gr |
| Date: 13/Jul/2002 |
| Software: AVR-GCC with AVR-AS |
| Target: any AVR device |
| Comments: This software is FREE. |
| |
| *****************************************************************************/ |
| |
| #include <io.h> |
| #include "i2c.h" |
| |
| #ifndef CONCAT1 |
| #define CONCAT1(a, b) CONCAT2(a, b) |
| #endif |
| |
| #ifndef CONCAT2 |
| #define CONCAT2(a, b) a ## b |
| #endif |
| |
| |
| /* Conversion of microseconds to the right value for the delay function */ |
| #define I2C_DELAY ( (I2C_DELAY_TIME*(F_CPU/60000))/100 ) |
| #define I2C_TIMEOUT ( (I2C_TIMEOUT_TIME*(F_CPU/60000))/100 ) |
| |
| /* Register name forming */ |
| #define I2C_SDA_OUT_REG CONCAT1(PORT, I2C_SDA_PORT) |
| #define I2C_SCL_OUT_REG CONCAT1(PORT, I2C_SCL_PORT) |
| #define I2C_SDA_DDR_REG CONCAT1(DDR, I2C_SDA_PORT) |
| #define I2C_SCL_DDR_REG CONCAT1(DDR, I2C_SCL_PORT) |
| #define I2C_SDA_PIN_REG CONCAT1(PIN, I2C_SDA_PORT) |
| #define I2C_SCL_PIN_REG CONCAT1(PIN, I2C_SCL_PORT) |
| |
| /* Conversion of microseconds to the right value for the delay function */ |
| #define I2C_DELAY ( (I2C_DELAY_TIME*(F_CPU/60000))/100 ) |
| #define I2C_TIMEOUT ( (I2C_TIMEOUT_TIME*(F_CPU/60000))/100 ) |
| |
| /* Pin states */ |
| #define SCL_1() cbi(I2C_SCL_DDR_REG, SCL_PIN) |
| #define SCL_0() sbi(I2C_SCL_DDR_REG, SCL_PIN) |
| #define SDA_1() cbi(I2C_SDA_DDR_REG, SDA_PIN) |
| #define SDA_0() sbi(I2C_SDA_DDR_REG, SDA_PIN) |
| |
| #define RELEASE_I2C_BUS() { SCL_1(); SDA_1(); } |
| |
| /*#################################################################################################*/ |
| |
| static void delay(unsigned long us) |
| { |
| |
| while ( us ) { us--; } /* 6 cpu cycles per loop */ |
| |
| } |
| /*#################################################################################################*/ |
| |
| void i2c_init(void) |
| { |
| cbi(I2C_SDA_OUT_REG, SDA_PIN); |
| cbi(I2C_SCL_OUT_REG, SCL_PIN); |
| RELEASE_I2C_BUS(); |
| delay(I2C_TIMEOUT); |
| i2c_start(); |
| delay(I2C_TIMEOUT); |
| i2c_stop(); |
| delay(I2C_TIMEOUT); |
| |
| |
| return; |
| } |
| /*#################################################################################################*/ |
| |
| void i2c_start(void) |
| { |
| RELEASE_I2C_BUS(); |
| delay(I2C_DELAY); |
| SDA_0(); |
| delay(I2C_DELAY); |
| SCL_0(); |
| delay(I2C_DELAY); |
| |
| return; |
| } |
| /*#################################################################################################*/ |
| |
| void i2c_stop(void) |
| { |
| SDA_0(); |
| SCL_1(); |
| delay(I2C_DELAY); |
| SDA_1(); |
| delay(I2C_DELAY); |
| SCL_0(); |
| delay(I2C_DELAY); |
| |
| return; |
| } |
| /*#################################################################################################*/ |
| |
| unsigned char i2c_transmit(unsigned char data) |
| { |
| register unsigned char bit=0; |
| |
| for(bit=0; bit<=7; bit++) |
| { |
| if( data & 0x80 ) { SDA_1(); } else { SDA_0(); } |
| SCL_1(); |
| delay(I2C_DELAY); |
| SCL_0(); |
| delay(I2C_DELAY); |
| data = (data<<1); |
| } |
| /* Look for AKNOWLEDGE */ |
| RELEASE_I2C_BUS(); |
| delay(I2C_DELAY); |
| |
| |
| if( bit_is_clear(I2C_SDA_PIN_REG, SDA_PIN) ) |
| { |
| SCL_0(); |
| delay(I2C_DELAY); |
| } |
| else{ |
| delay(I2C_TIMEOUT); |
| if( bit_is_clear(I2C_SDA_PIN_REG, SDA_PIN) ) |
| { |
| SCL_0(); |
| delay(I2C_DELAY); |
| } |
| else { return(I2C_ERROR_DEVICE_NOT_RESPONDING); } |
| } |
| |
| |
| if( bit_is_clear(I2C_SDA_PIN_REG, SDA_PIN) ) |
| { |
| delay(I2C_TIMEOUT); |
| if( bit_is_clear(I2C_SDA_PIN_REG, SDA_PIN) ) { return(I2C_ERROR_DEVICE_BUSY); } |
| } |
| |
| |
| return(I2C_NO_ERROR); |
| } |
| /*#################################################################################################*/ |
| |
| unsigned char i2c_receive(unsigned char ack) |
| { |
| register unsigned char bit=0, data=0; |
| |
| SDA_1(); |
| for(bit=0; bit<=7; bit++) |
| { |
| SCL_1(); |
| delay(I2C_DELAY); |
| data = (data<<1); |
| if( bit_is_set(I2C_SDA_PIN_REG, SDA_PIN) ) { data++; } |
| SCL_0(); |
| delay(I2C_DELAY); |
| } |
| |
| /* if CONTINUE then send AKNOWLEDGE else if QUIT do not send AKNOWLEDGE (send Nack) */ |
| if(ack==I2C_CONTINUE) { SDA_0(); } else { SDA_1(); } |
| SCL_1(); |
| delay(I2C_DELAY); |
| SCL_0(); |
| delay(I2C_DELAY); |
| |
| return data; |
| } |
| /*#################################################################################################*/ |
| |
| |