recipes/i2c/files/i2c.h

   1 /****************************************************************************
   2 *
   3 *   Copyright (c) 2006 Dave Hylands     <dhylands@gmail.com>
   4 *
   5 *   This program is free software; you can redistribute it and/or modify
   6 *   it under the terms of the GNU General Public License version 2 as
   7 *   published by the Free Software Foundation.
   8 *
   9 *   Alternatively, this software may be distributed under the terms of BSD
  10 *   license.
  11 *
  12 *   See README and COPYING for more details.
  13 *
  14 ****************************************************************************/
  15 /**
  16 *
  17 *   @file   i2c.h
  18 *
  19 *   @brief  Global definitions for interfacing with the AVR TWI (aka I2C)
  20 *           hardware
  21 *
  22 ****************************************************************************/
  23 /**
  24 *   @defgroup   xxx   Readable version of xxx.
  25 *
  26 *   @brief   Brief description of what xxx does.
  27 *
  28 *   Longer description of what xxx does.
  29 *
  30 ****************************************************************************/
  31
  32 #if !defined( I2C_H )
  33 #define I2C_H               /**< Include Guard                             */
  34
  35 /* ---- Include Files ---------------------------------------------------- */
  36
  37 #include <inttypes.h>
  38
  39 #if !defined( CONFIG_H )
  40 #   include "Config.h"
  41 #endif
  42
  43
  44 /**
  45  *  @addtogroup I2C
  46  *  @{
  47  */
  48
  49 /* ---- Constants and Types ---------------------------------------------- */
  50
  51 /**
  52  *  Error Codes
  53  */
  54
  55 #define I2C_ERROR_NONE               0  // No Error
  56 #define I2C_ERROR_ADDR_NACK         -1  // No response to SLA+R/W
  57 #define I2C_ERROR_DATA_NACK         -2  // NACK during data transmission
  58 #define I2C_ERROR_ARBITRATION_LOST  -3  // Lost arbitration
  59 #define I2C_ERROR_BAD_LEN           -4  // Length is wonky
  60 #define I2C_ERROR_BAD_CRC           -5  // CRC failed
  61 #define I2C_ERROR_BUS_ERROR         -6  // Someting weird on the i2c bus
  62
  63 typedef int8_t  I2C_Error_t;
  64
  65 /**
  66  *  Since we're loosely following the SMBus spec, we restrict the amount
  67  *  of data in each transaction to 32 bytes.
  68  */
  69
  70 #define I2C_MAX_DATA_LEN    32
  71
  72 /**
  73  *  I2C_Addr_t can contain the address of any device on the bus. This
  74  *  module only supports 7 bit addressing.
  75  */
  76
  77 typedef uint8_t I2C_Addr_t;
  78
  79 /**
  80  *  The I2C_CRC macro can be used to remove all CRC support at compile time.
  81  */
  82
  83 #if CFG_I2C_USE_CRC
  84 #   define  I2C_CRC(x)  x
  85 #else
  86
  87 #   define  I2C_CRC(x)
  88 #endif
  89
  90
  91 /**
  92  *  I2C_Data_t encapsulates the data being read or written on the i2c bus.
  93  *  This module follows the SMBus spec, whihch specifies a maximum payload
  94  *  of 32 bytes.
  95  */
  96
  97 typedef struct
  98 {
  99 #if CFG_I2C_USE_CRC
 100     uint8_t     m_crc;
 101 #endif
 102
 103
 104     //  For reads, m_len is the number of bytes actually read (doesn't include
 105     //  the CRC - if present). If a block transfer was performed which has a
 106     //  length byte, this length will include the length byte.
 107
 108     uint8_t     m_len;
 109
 110     // Note: Under SMBus, a block write can consist of a command, a length,
 111     //       32 bytes of payload, and a CRC.
 112     //
 113     // A read response can consist of a length, 32 bytes of data, and a CRC.
 114
 115     uint8_t     m_data[ I2C_MAX_DATA_LEN  + 2]; // +1 for the command, +1 for length
 116
 117 } I2C_Data_t;
 118
 119 /* ---- Variable Externs ------------------------------------------------- */
 120
 121 /**
 122  *  Description of variable.
 123  */
 124
 125 /* ---- Function Prototypes ---------------------------------------------- */
 126
 127 /*
 128  *  Just include prototypes here. Put full descriptions in the .c files.
 129  */
 130
 131 /** @} */
 132
 133 #endif /* I2C_H */
 134
 135