File content as of revision 1:4e4194db7cd6:

/*!
LT_I2C: Routines to communicate with ATmega328P's hardware I2C port.

@verbatim

LT_I2C contains the low level routines to communicate with devices using the
ATMega328's onboard hardware I2C port. Each routine checks the Two Wire Status
Register (TWSR) at the end of the transaction and returns 0 if successful and 1
if not successful.

I2C Frequency = (CPU Clock frequency)/(16+2(TWBR)*Prescaler)

TWBR-Two Wire Bit Rate Register
TWCR=Two Wire Control Register (TWINT TWEA TWSTA TWSTO TWWC TWEN - TWIE)
TWSR=Two Wire Status Register

Prescaler Values:
TWSR1  TWSR0  Prescaler
   0      0      1
   0      1      4
   1      0      16
   1      1      64

Examples:
CPU Frequency = 16Mhz on Arduino Uno
I2C Frequency  Prescaler  TWSR1  TWSR0  TWBR
  1khz         64         1      1      125
  10khz        64         1      1      12
  50khz        16         1      0      10
  100khz        4         0      1      18
  400khz        1         0      0      12

@endverbatim

REVISION HISTORY
$Revision: 5469 $
$Date: 2016-07-22 17:01:32 -0700 (Fri, 22 Jul 2016) $

Copyright (c) 2013, Linear Technology Corp.(LTC)
All rights reserved.

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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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*/

//! @defgroup LT_I2C LT_I2C: Routines to Communicate With ATmega328P's hardware I2C port.

/*! @file
    @ingroup LT_I2C
    Library for LT_I2C: Routines to Communicate With ATmega328P's hardware I2C port.
*/

//#include <Arduino.h>
#include <stdint.h>
//#include <util/delay.h>
#include "Linduino.h"
#include "LT_I2C.h"
#include "mbed.h"

//! CPU master clock frequency
#ifndef F_CPU
#define F_CPU 16000000UL
#endif
Serial pc1(USBTX, USBRX, 9600);


I2C i2c(I2C_SDA , I2C_SCL);

// Read a byte of data at register specified by "command", store in "value"
int8_t i2c_read_byte_data(uint8_t address, uint8_t command, uint8_t *value)
{
    int8_t ret = 0;
    
    char cmd1[1];
    cmd1[0] = command;
    char v[1];
    v[0] = 0;
    
    ret |= i2c.write((address<<1) | I2C_WRITE_BIT, cmd1, 1, true);  
    ret |= i2c.read((address<<1) | I2C_READ_BIT, v, 1, false);
    
    *value = v[0];
    
    if (ret == 0) {
        return 0; //success
    }
    return(1);                                       
}

// Write a byte of data to register specified by "command"
int8_t i2c_write_byte_data(uint8_t address, uint8_t command, uint8_t value)
{
    int8_t ret = 0;
    char cmd[2];
    cmd[0] = command;
    cmd[1] = value;
    ret |= i2c.write((address<<1) | I2C_WRITE_BIT, cmd, 2, false);         

    if (ret == 0) {
        return 0; //success
    }
    return(1);
}

//// Read a byte of data at register specified by "command", store in "value"
//int8_t i2c_read_byte_data(uint8_t address, uint8_t command, uint8_t *value)
//{
//    checkDevice();
//    int8_t ret = 1;
//
//    i2c.start();                                            // I2C START
//    ret &= i2c.write((address<<1) | I2C_WRITE_BIT);         // Write 7 bit address with W bit
//    pc1.printf("[read] ret 0: %d\n", ret);
//    ret &= i2c.write(command);                              // Set register to be read to command
//    pc1.printf("[read] ret 1: %d\n", ret);
//    i2c.start();                                            //2nd start condition
//    ret &= i2c.write((address<<1) | I2C_READ_BIT);          // Write 7 bit address with R bit
//    pc1.printf("[read] ret 2: %d\n", ret);
//    *value = i2c.read(WITH_NACK);                           // Read byte from buffer with *NAK*
//    i2c.stop();                                             // I2C STOP
//    if (ret == 1) {
//        return 0; //success
//    }
//    return(1);                                       
//}
//
//// Write a byte of data to register specified by "command"
//int8_t i2c_write_byte_data(uint8_t address, uint8_t command, uint8_t value)
//{
//    checkDevice();
//    int8_t ret = 1;
//
//    i2c.start();                                           // I2C START
//    ret &= i2c.write((address<<1) | I2C_WRITE_BIT);         // Write 7 bit address with W bit
//    pc1.printf("[write] ret 0: %d\n", ret);
//    ret &= i2c.write(command);                              // Set register to be read to command
//    pc1.printf("[write] ret 1: %d\n", ret);
//    ret &= i2c.write(value);
//    pc1.printf("[write] ret 2: %d\n", ret);
//    i2c.stop();
//    if (ret == 1) {
//        return 0; //success
//    }
//    return(1);
//}

// Read a 16-bit word of data from register specified by "command"
//int8_t i2c_read_word_data(uint8_t address, uint8_t command, uint16_t *value)
//{
//    int8_t ret = 1;
//
//    union {
//        uint8_t b[2];
//        uint16_t w;
//    } data;
//
//    i2c.start();
//    ret &= i2c.write((address << 1) | I2C_WRITE_BIT);       // Write 7 bit address with W bit
//    ret &= i2c.write(command);                              // Set register to be read to command
//    i2c.start(); //2nd start condition
//    ret &= i2c.write((address<<1) | I2C_READ_BIT);          // Write 7 bit address with R bit
//
//    data.b[1] = i2c.read(WITH_ACK);                         // Read MSB from buffer
//    data.b[0] = i2c.read(WITH_NACK);                        // Read LSB from buffer
//    i2c.stop();
//
//    *value = data.w;
//    if (ret == 1) {
//        return 0;
//    }
//    return(1);
//}
//
//// Write a 16-bit word of data to register specified by "command"
//int8_t i2c_write_word_data(uint8_t address, uint8_t command, uint16_t value)
//{
//    int8_t ret = 1;
//
//    union {
//        uint8_t b[2];
//        uint16_t w;
//    } data;
//    data.w = value;
//
//    i2c.start();
//    ret &= i2c.write((address<<1) | I2C_WRITE_BIT);         // Write 7 bit address with W bit
//    ret &= i2c.write(command);                              // Set register to be read to command
//    ret &= i2c.write(data.b[1]);                            // Write MSB
//    ret &= i2c.write(data.b[0]);                            // Write LSB;
//
//    i2c.stop();                                             // I2C STOP
//    if (ret == 1) {
//        return 0;
//    }
//    return(1);
//}

int8_t i2c_read_word_data(uint8_t address, uint8_t command, uint16_t *value)
{
    int8_t ret = 0;
    

    union { 
       char b[2]; 
       uint16_t w;
    } data; 
    
    char writedata[2];
    writedata[0] = command; //msb
    writedata[1] = command+1; //lsb
    
    ret |= i2c.write((address << 1) | I2C_WRITE_BIT, &writedata[0], 1, true); 
    ret |= i2c.read((address << 1) | I2C_READ_BIT, &data.b[1], 1, false);
    ret |= i2c.write((address << 1) | I2C_WRITE_BIT, &writedata[1], 1, true); 
    ret |= i2c.read((address << 1) | I2C_READ_BIT, &data.b[0], 1, false);
    
    
    *value = data.w;
    
    if (ret == 0) {
        return 0;
    }
    return(1);
}

// Write a 16-bit word of data to register specified by "command"
int8_t i2c_write_word_data(uint8_t address, uint8_t command, uint16_t value)
{
    int8_t ret = 0;
    
    union
    {
        uint8_t b[2];
        uint16_t w;
    } data;
    data.w = value;
    
    char cmd[3];
    cmd[0] = command;
    cmd[1] = data.b[1];
    cmd[2] = data.b[0];

    ret |= i2c.write((address<<1) | I2C_WRITE_BIT, cmd, 3, false);

    if (ret == 0) {
        return 0;
    }
    return(1);
}