LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2012.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2012  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 bool TWI_SendByte(const uint8_t Byte)
 101 {
 102         TWDR = Byte;
 103         TWCR = ((1 << TWINT) | (1 << TWEN));
 104         while (!(TWCR & (1 << TWINT)));
 105
 106         return ((TWSR & TW_STATUS_MASK) == TW_MT_DATA_ACK);
 107 }
 108
 109 bool TWI_ReceiveByte(uint8_t* const Byte,
 110                                          const bool LastByte)
 111 {
 112         uint8_t TWCRMask;
 113
 114         if (LastByte)
 115           TWCRMask = ((1 << TWINT) | (1 << TWEN));
 116         else
 117           TWCRMask = ((1 << TWINT) | (1 << TWEN) | (1 << TWEA));
 118
 119         TWCR = TWCRMask;
 120         while (!(TWCR & (1 << TWINT)));
 121         *Byte = TWDR;
 122
 123         uint8_t Status = (TWSR & TW_STATUS_MASK);
 124
 125         return ((LastByte) ? (Status == TW_MR_DATA_NACK) : (Status == TW_MR_DATA_ACK));
 126 }
 127
 128 uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
 129                        const uint8_t TimeoutMS,
 130                        const uint8_t* InternalAddress,
 131                        uint8_t InternalAddressLen,
 132                        uint8_t* Buffer,
 133                        uint8_t Length)
 134 {
 135         uint8_t ErrorCode;
 136
 137         if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
 138                                                TimeoutMS)) == TWI_ERROR_NoError)
 139         {
 140                 while (InternalAddressLen--)
 141                 {
 142                         if (!(TWI_SendByte(*(InternalAddress++))))
 143                         {
 144                                 ErrorCode = TWI_ERROR_SlaveNAK;
 145                                 break;
 146                         }
 147                 }
 148
 149                 if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_READ,
 150                                                                                            TimeoutMS)) == TWI_ERROR_NoError)
 151                 {
 152                         while (Length--)
 153                         {
 154                                 if (!(TWI_ReceiveByte(Buffer++, (Length == 0))))
 155                                 {
 156                                         ErrorCode = TWI_ERROR_SlaveNAK;
 157                                         break;
 158                                 }
 159                         }
 160
 161                         TWI_StopTransmission();
 162                 }
 163         }
 164
 165         return ErrorCode;
 166 }
 167
 168 uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
 169                         const uint8_t TimeoutMS,
 170                         const uint8_t* InternalAddress,
 171                         uint8_t InternalAddressLen,
 172                         const uint8_t* Buffer,
 173                         uint8_t Length)
 174 {
 175         uint8_t ErrorCode;
 176
 177         if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
 178                                                TimeoutMS)) == TWI_ERROR_NoError)
 179         {
 180                 while (InternalAddressLen--)
 181                 {
 182                         if (!(TWI_SendByte(*(InternalAddress++))))
 183                         {
 184                                 ErrorCode = TWI_ERROR_SlaveNAK;
 185                                 break;
 186                         }
 187                 }
 188
 189                 while (Length--)
 190                 {
 191                         if (!(TWI_SendByte(*(Buffer++))))
 192                         {
 193                                 ErrorCode = TWI_ERROR_SlaveNAK;
 194                                 break;
 195                         }
 196                 }
 197
 198                 TWI_StopTransmission();
 199         }
 200
 201         return ErrorCode;
 202 }
 203