====== HS-I2C (HighSpeed) ======
This page introduces how you can I2C interface using Expansion Board.

The Expansion Board have two I2C devices.\\
You can use the devices via H/W I2C(I2C-A : HS-I2C).

{{:en:xu4:xu4_hsi2c_with_expansion.png?700|}}

**H/W I2C(I2C-A : HS-I2C)**
^  Kernel 3.10.y\\ (node name)  ^  Kernel 4.9.y\\ (node name)  ^  Pin Number\\ (XU4-CON11)  ^  Net Name            ^  Export Number  ^  Description  ^
|  /dev/i2c-1                   |  /dev/i2c-5                  |  4                         |  GPA2[2](I2C_5.SDA)  |  187            |  SDA          |
|  :::                          |  :::                         |  6                         |  GPA2[3](I2C_5.SCL)  |  188            |  SCL          |


<note warning>I2C-A(HS-I2C) doesn't work with i2cdetect command on Kenrnel 3.10.y</note>

  * Using the H/W I2C(I2C-A : HS-I2C) with Expansion Board. I2C Physical Address : 0x12CB0000


**HW-HSI2C Test Code**

<file c xu4_hsi2c.c>
//------------------------------------------------------------------------------------------------------------
//
// ODROID-XU4 with Shifter Shield I2C Test Application.
// I2C Node : /dev/i2c-3
//
// Compile : gcc -o <create excute file name> <source file name>
// Run : sudo ./<created excute file name>
//
//------------------------------------------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/ioctl.h>

#include <unistd.h>
#include <string.h>
#include <time.h>

//------------------------------------------------------------------------------------------------------------
//
// Global handle Define
//
//------------------------------------------------------------------------------------------------------------

// I2C definitions

#define I2C_SLAVE	0x0703
#define I2C_SMBUS	0x0720	/* SMBus-level access */

#define I2C_SMBUS_READ	1
#define I2C_SMBUS_WRITE	0

// SMBus transaction types

#define I2C_SMBUS_QUICK		    0
#define I2C_SMBUS_BYTE		    1
#define I2C_SMBUS_BYTE_DATA	    2 
#define I2C_SMBUS_WORD_DATA	    3
#define I2C_SMBUS_PROC_CALL	    4
#define I2C_SMBUS_BLOCK_DATA	    5
#define I2C_SMBUS_I2C_BLOCK_BROKEN  6
#define I2C_SMBUS_BLOCK_PROC_CALL   7		/* SMBus 2.0 */
#define I2C_SMBUS_I2C_BLOCK_DATA    8

// SMBus messages
#define I2C_SMBUS_BLOCK_MAX	    32	/* As specified in SMBus standard */	
#define I2C_SMBUS_I2C_BLOCK_MAX	32	/* Not specified but we use same structure */

// Structures used in the ioctl() calls

union i2c_smbus_data
{
  uint8_t   byte;
  uint16_t  word;
  uint8_t   block [I2C_SMBUS_BLOCK_MAX + 2] ;	// block [0] is used for length + one more for PEC
};

struct i2c_smbus_ioctl_data
{
  char                  read_write;
  uint8_t               command ;
  int                   size;
  union i2c_smbus_data  *data;
};

static inline int i2c_smbus_access (int fd, char rw, uint8_t command, int size, union i2c_smbus_data *data)
{
  struct i2c_smbus_ioctl_data args ;

  args.read_write = rw ;
  args.command    = command ;
  args.size       = size ;
  args.data       = data ;
  return ioctl (fd, I2C_SMBUS, &args) ;
}

int i2c_smbus_read_byte_data(int fd, int reg)
{
  union i2c_smbus_data data;

  if (i2c_smbus_access (fd, I2C_SMBUS_READ, reg, I2C_SMBUS_BYTE_DATA, &data))
    return -1 ;
  else
    return data.byte & 0xFF ;
}
//------------------------------------------------------------------------------------------------------------
//
// I2C:
//
//------------------------------------------------------------------------------------------------------------
// kernel 4.9.y device node
// const char *i2cHandleNode = "/dev/i2c-5";

// kernel 3.10.y device node
const char *i2cHandleNode = "/dev/i2c-1";
static  int i2c_fd = -1;

//------------------------------------------------------------------------------------------------------------
//------------------------------------------------------------------------------------------------------------
//
// LCD Update Function:
//
//------------------------------------------------------------------------------------------------------------
static void data_update (void)
{
    int val1, val2;
    static  unsigned long   count = 0;

    if(i2c_fd == -1)    return;
    
    // set BH1780 Sensor I2C Address
    if(ioctl(i2c_fd, I2C_SLAVE, 0x29) < 0)  {
        fprintf(stdout, "%s : ioctl BH1780 I2C_SLAVE Setup Error!\n", __func__);
        return;
    }
    
    // BH1780 Part ID Read
    val1 = i2c_smbus_read_byte_data(i2c_fd, 0x0A);
    
    // set Pressure Sensor I2C Address
    if(ioctl(i2c_fd, I2C_SLAVE, 0x77) < 0)  {
        fprintf(stdout, "%s : ioctl PRESSURE I2C_SLAVE Setup Error!\n", __func__);
        return;
    }

    // Pressure Sensor CHIP ID Read
    val2 = i2c_smbus_read_byte_data(i2c_fd, 0xD0);

    fprintf(stdout, "%s : count = %ld BH1780 ID = 0x%02X, PRESSURE ID = 0x%02X\n", __func__, count++, val1, val2);
}

//------------------------------------------------------------------------------------------------------------
//
// system init
//
//------------------------------------------------------------------------------------------------------------
int system_init(void)
{
    if((i2c_fd = open(i2cHandleNode, O_RDWR)) < 0)  {
        fprintf(stdout, "%s : %s Open Error!\n", __func__, i2cHandleNode);
        return  -1;
    }
    return  0;
 }

//------------------------------------------------------------------------------------------------------------
//
// Start Program
//
//------------------------------------------------------------------------------------------------------------
int main (int argc, char *argv[])
{
    if (system_init() < 0)
    {
        fprintf (stderr, "%s: System Init failed\n", __func__); fflush(stdout);
        return -1;
    }

    for(;;)    {
        usleep(100000);
        data_update();  fflush(stdout);
    }

    return 0 ;
}

//------------------------------------------------------------------------------------------------------------
//------------------------------------------------------------------------------------------------------------

</file>