LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2011.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2011  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 #define  __INCLUDE_FROM_TWI_C
  32 #include "../TWI.h"
  33
  34 uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
  35                               const uint8_t TimeoutMS)
  36 {
  37         for (;;)
  38         {
  39                 bool     BusCaptured = false;
  40                 uint16_t TimeoutRemaining;
  41
  42                 TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
  43
  44                 TimeoutRemaining = (TimeoutMS * 100);
  45                 while (TimeoutRemaining-- && !(BusCaptured))
  46                 {
  47                         if (TWCR & (1 << TWINT))
  48                         {
  49                                 switch (TWSR & TW_STATUS_MASK)
  50                                 {
  51                                         case TW_START:
  52                                         case TW_REP_START:
  53                                                 BusCaptured = true;
  54                                                 break;
  55                                         case TW_MT_ARB_LOST:
  56                                                 TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
  57                                                 continue;
  58                                         default:
  59                                                 TWCR = (1 << TWEN);
  60                                                 return TWI_ERROR_BusFault;
  61                                 }
  62                         }
  63
  64                         _delay_us(10);
  65                 }
  66
  67                 if (!(TimeoutRemaining))
  68                 {
  69                         TWCR = (1 << TWEN);
  70                         return TWI_ERROR_BusCaptureTimeout;
  71                 }
  72
  73                 TWDR = SlaveAddress;
  74                 TWCR = ((1 << TWINT) | (1 << TWEN));
  75
  76                 TimeoutRemaining = (TimeoutMS * 100);
  77                 while (TimeoutRemaining--)
  78                 {
  79                         if (TWCR & (1 << TWINT))
  80                           break;
  81
  82                         _delay_us(10);
  83                 }
  84
  85                 if (!(TimeoutRemaining))
  86                   return TWI_ERROR_SlaveResponseTimeout;
  87
  88                 switch (TWSR & TW_STATUS_MASK)
  89                 {
  90                         case TW_MT_SLA_ACK:
  91                         case TW_MR_SLA_ACK:
  92                                 return TWI_ERROR_NoError;
  93                         default:
  94                                 TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
  95                                 return TWI_ERROR_SlaveNotReady;
  96                 }
  97         }
  98 }
  99
 100 uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
 101                        const uint8_t TimeoutMS,
 102                        const uint8_t* InternalAddress,
 103                        const uint8_t InternalAddressLen,
 104                        uint8_t* Buffer,
 105                        uint8_t Length)
 106 {
 107         uint8_t ErrorCode;
 108
 109         if ((ErrorCode = TWI_WritePacket(SlaveAddress, TimeoutMS, InternalAddress, InternalAddressLen,
 110                                          NULL, 0)) != TWI_ERROR_NoError)
 111         {
 112                 return ErrorCode;
 113         }
 114
 115         if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_READ,
 116                                                                                    TimeoutMS)) == TWI_ERROR_NoError)
 117         {
 118                 while (Length--)
 119                 {
 120                         if (!(TWI_ReceiveByte(Buffer++, (Length == 0))))
 121                         {
 122                                 ErrorCode = TWI_ERROR_SlaveNAK;
 123                                 break;
 124                         }
 125                 }
 126
 127                 TWI_StopTransmission();
 128         }
 129
 130         return ErrorCode;
 131 }
 132
 133 uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
 134                         const uint8_t TimeoutMS,
 135                         const uint8_t* InternalAddress,
 136                         uint8_t InternalAddressLen,
 137                         const uint8_t* Buffer,
 138                         uint8_t Length)
 139 {
 140         uint8_t ErrorCode;
 141
 142         if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
 143                                                TimeoutMS)) == TWI_ERROR_NoError)
 144         {
 145                 while (InternalAddressLen--)
 146                 {
 147                         if (!(TWI_SendByte(*(InternalAddress++))))
 148                         {
 149                                 ErrorCode = TWI_ERROR_SlaveNAK;
 150                                 break;
 151                         }
 152                 }
 153
 154                 while (Length--)
 155                 {
 156                         if (!(TWI_SendByte(*(Buffer++))))
 157                         {
 158                                 ErrorCode = TWI_ERROR_SlaveNAK;
 159                                 break;
 160                         }
 161                 }
 162
 163                 TWI_StopTransmission();
 164         }
 165
 166         return ErrorCode;
 167 }