LUFA/Drivers/Peripheral/TWI.c

   1 /*
   2      Copyright (C) Dean Camera, 2011.
   3
   4   dean [at] fourwalledcubicle [dot] com
   5            www.lufa-lib.org
   6 */
   7
   8 #include "TWI.h"
   9
  10 uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
  11                               const uint8_t TimeoutMS)
  12 {
  13         for (;;)
  14         {
  15                 bool     BusCaptured = false;
  16                 uint16_t TimeoutRemaining;
  17
  18                 TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
  19
  20                 TimeoutRemaining = (TimeoutMS * 100);
  21                 while (TimeoutRemaining-- && !(BusCaptured))
  22                 {
  23                         if (TWCR & (1 << TWINT))
  24                         {
  25                                 switch (TWSR & TW_STATUS_MASK)
  26                                 {
  27                                         case TW_START:
  28                                         case TW_REP_START:
  29                                                 BusCaptured = true;
  30                                                 break;
  31                                         case TW_MT_ARB_LOST:
  32                                                 TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
  33                                                 continue;
  34                                         default:
  35                                                 TWCR = (1 << TWEN);
  36                                                 return TWI_ERROR_BusFault;
  37                                 }
  38                         }
  39
  40                         _delay_us(10);
  41                 }
  42
  43                 if (!(TimeoutRemaining))
  44                 {
  45                         TWCR = (1 << TWEN);
  46                         return TWI_ERROR_BusCaptureTimeout;
  47                 }
  48
  49                 TWDR = SlaveAddress;
  50                 TWCR = ((1 << TWINT) | (1 << TWEN));
  51
  52                 TimeoutRemaining = (TimeoutMS * 100);
  53                 while (TimeoutRemaining--)
  54                 {
  55                         if (TWCR & (1 << TWINT))
  56                           break;
  57
  58                         _delay_us(10);
  59                 }
  60
  61                 if (!(TimeoutRemaining))
  62                   return TWI_ERROR_SlaveResponseTimeout;
  63
  64                 switch (TWSR & TW_STATUS_MASK)
  65                 {
  66                         case TW_MT_SLA_ACK:
  67                         case TW_MR_SLA_ACK:
  68                                 return TWI_ERROR_NoError;
  69                         default:
  70                                 TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
  71                                 return TWI_ERROR_SlaveNotReady;
  72                 }
  73         }
  74 }
  75
  76 uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
  77                        const uint8_t TimeoutMS,
  78                        const uint8_t* InternalAddress,
  79                        uint8_t InternalAddressLen,
  80                        uint8_t* Buffer,
  81                        uint8_t Length)
  82 {
  83         uint8_t ErrorCode;
  84
  85         if ((ErrorCode = TWI_WritePacket(SlaveAddress, TimeoutMS, InternalAddress, InternalAddressLen,
  86                                          NULL, 0)) != TWI_ERROR_NoError)
  87         {
  88                 return ErrorCode;
  89         }
  90
  91         if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_READ,
  92                                                                                    TimeoutMS)) == TWI_ERROR_NoError)
  93         {
  94                 while (Length--)
  95                 {
  96                         if (!(TWI_ReceiveByte(Buffer++, (Length == 0))))
  97                         {
  98                                 ErrorCode = TWI_ERROR_SlaveNAK;
  99                                 break;
 100                         }
 101                 }
 102
 103                 TWI_StopTransmission();
 104         }
 105
 106         return ErrorCode;
 107 }
 108
 109 uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
 110                         const uint8_t TimeoutMS,
 111                         const uint8_t* InternalAddress,
 112                         uint8_t InternalAddressLen,
 113                         const uint8_t* Buffer,
 114                         uint8_t Length)
 115 {
 116         uint8_t ErrorCode;
 117
 118         if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
 119                                                TimeoutMS)) == TWI_ERROR_NoError)
 120         {
 121                 while (InternalAddressLen--)
 122                 {
 123                         if (!(TWI_SendByte(*(InternalAddress++))))
 124                         {
 125                                 ErrorCode = TWI_ERROR_SlaveNAK;
 126                                 break;
 127                         }
 128                 }
 129
 130                 while (Length--)
 131                 {
 132                         if (!(TWI_SendByte(*(Buffer++))))
 133                         {
 134                                 ErrorCode = TWI_ERROR_SlaveNAK;
 135                                 break;
 136                         }
 137                 }
 138
 139                 TWI_StopTransmission();
 140         }
 141
 142         return ErrorCode;
 143 }