git.sur5r.net Git - freertos/blob - Demo/WizNET_DEMO_GCC_ARM7/i2cISR.c

   1 /*\r
   2         FreeRTOS.org V4.5.0 - Copyright (C) 2003-2007 Richard Barry.\r
   3 \r
   4         This file is part of the FreeRTOS.org distribution.\r
   5 \r
   6         FreeRTOS.org is free software; you can redistribute it and/or modify\r
   7         it under the terms of the GNU General Public License as published by\r
   8         the Free Software Foundation; either version 2 of the License, or\r
   9         (at your option) any later version.\r
  10 \r
  11         FreeRTOS.org is distributed in the hope that it will be useful,\r
  12         but WITHOUT ANY WARRANTY; without even the implied warranty of\r
  13         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r
  14         GNU General Public License for more details.\r
  15 \r
  16         You should have received a copy of the GNU General Public License\r
  17         along with FreeRTOS.org; if not, write to the Free Software\r
  18         Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\r
  19 \r
  20         A special exception to the GPL can be applied should you wish to distribute\r
  21         a combined work that includes FreeRTOS.org, without being obliged to provide\r
  22         the source code for any proprietary components.  See the licensing section \r
  23         of http://www.FreeRTOS.org for full details of how and when the exception\r
  24         can be applied.\r
  25 \r
  26         ***************************************************************************\r
  27         See http://www.FreeRTOS.org for documentation, latest information, license \r
  28         and contact details.  Please ensure to read the configuration and relevant \r
  29         port sections of the online documentation.\r
  30 \r
  31         Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along\r
  32         with commercial development and support options.\r
  33         ***************************************************************************\r
  34 */\r
  35 \r
  36 \r
  37 /* Standard includes. */\r
  38 #include <stdlib.h>\r
  39 \r
  40 /* Scheduler include files. */\r
  41 #include "FreeRTOS.h"\r
  42 #include "task.h"\r
  43 #include "queue.h"\r
  44 #include "semphr.h"\r
  45 \r
  46 /* Application includes. */\r
  47 #include "i2c.h"\r
  48 \r
  49 /*-----------------------------------------------------------*/\r
  50 \r
  51 /* Bit definitions within the I2CONCLR register. */\r
  52 #define i2cSTA_BIT              ( ( unsigned portCHAR ) 0x20 )\r
  53 #define i2cSI_BIT               ( ( unsigned portCHAR ) 0x08 )\r
  54 #define i2cSTO_BIT              ( ( unsigned portCHAR ) 0x10 )\r
  55 #define i2cAA_BIT               ( ( unsigned portCHAR ) 0x04 )\r
  56 \r
  57 /* Status codes for the I2STAT register. */\r
  58 #define i2cSTATUS_START_TXED                    ( 0x08 )\r
  59 #define i2cSTATUS_REP_START_TXED                ( 0x10 )\r
  60 #define i2cSTATUS_TX_ADDR_ACKED                 ( 0x18 )\r
  61 #define i2cSTATUS_DATA_TXED                             ( 0x28 )\r
  62 #define i2cSTATUS_RX_ADDR_ACKED                 ( 0x40 )\r
  63 #define i2cSTATUS_DATA_RXED                             ( 0x50 )\r
  64 #define i2cSTATUS_LAST_BYTE_RXED                ( 0x58 )\r
  65 \r
  66 /* Constants for operation of the VIC. */\r
  67 #define i2cCLEAR_VIC_INTERRUPT  ( 0 )\r
  68 \r
  69 /* Misc constants. */\r
  70 #define i2cJUST_ONE_BYTE_TO_RX  ( 1 )\r
  71 #define i2cBUFFER_ADDRESS_BYTES ( 2 )\r
  72 \r
  73 /* End the current transmission and free the bus. */\r
  74 #define i2cEND_TRANSMISSION( lStatus )                                  \\r
  75 {                                                                                                               \\r
  76         I2C_I2CONCLR = i2cAA_BIT;                                                       \\r
  77         I2C_I2CONSET = i2cSTO_BIT;                                                      \\r
  78         eCurrentState = eSentStart;                                                     \\r
  79         lTransactionCompleted = lStatus;                                        \\r
  80 }\r
  81 /*-----------------------------------------------------------*/\r
  82 \r
  83 /* Valid i2c communication states. */\r
  84 typedef enum\r
  85 {\r
  86         eSentStart,                             /*<< Last action was the transmission of a start bit. */\r
  87         eSentAddressForWrite,   /*<< Last action was the transmission of the slave address we are to write to. */\r
  88         eSentAddressForRead,    /*<< Last action was the transmission of the slave address we are to read from. */\r
  89         eSentData,                              /*<< Last action was the transmission of a data byte. */\r
  90         eReceiveData                    /*<< We expected data to be received. */\r
  91 } I2C_STATE;\r
  92 /*-----------------------------------------------------------*/\r
  93 \r
  94 /* Points to the message currently being sent. */\r
  95 volatile xI2CMessage *pxCurrentMessage = NULL;  \r
  96 \r
  97 /* The queue of messages waiting to be transmitted. */\r
  98 static xQueueHandle xMessagesForTx;\r
  99 \r
 100 /* Flag used to indicate whether or not the ISR is amid sending a message. */\r
 101 unsigned portLONG ulBusFree = ( unsigned portLONG ) pdTRUE;\r
 102 \r
 103 /* Setting this to true will cause the TCP task to think a message is \r
 104 complete and thus restart.  It can therefore be used under error states\r
 105 to force a restart. */\r
 106 volatile portLONG lTransactionCompleted = pdTRUE;\r
 107 \r
 108 /*-----------------------------------------------------------*/\r
 109 \r
 110 void vI2CISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxTxMessages, unsigned portLONG **ppulBusFree )\r
 111 {\r
 112         /* Create the queues used to hold Rx and Tx characters. */\r
 113         xMessagesForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( xI2CMessage * ) );\r
 114 \r
 115         /* Pass back a reference to the queue and bus free flag so the I2C API file \r
 116         can post messages. */\r
 117         *pxTxMessages = xMessagesForTx;\r
 118         *ppulBusFree = &ulBusFree;\r
 119 }\r
 120 /*-----------------------------------------------------------*/\r
 121 \r
 122 void vI2C_ISR( void ) __attribute__ (( naked ));\r
 123 void vI2C_ISR( void )\r
 124 {\r
 125         portENTER_SWITCHING_ISR();\r
 126 \r
 127         /* Variables must be static. */\r
 128 \r
 129         /* Holds the current transmission state. */                                                     \r
 130         static I2C_STATE eCurrentState = eSentStart;\r
 131         static portLONG lMessageIndex = -i2cBUFFER_ADDRESS_BYTES; /* There are two address bytes to send prior to the data. */\r
 132         static portBASE_TYPE xTaskWokenByTx;\r
 133         static portLONG lBytesLeft;\r
 134 \r
 135         xTaskWokenByTx = pdFALSE;\r
 136 \r
 137 \r
 138         /* The action taken for this interrupt depends on our current state. */\r
 139         switch( eCurrentState )\r
 140         {\r
 141                 case eSentStart :       \r
 142 \r
 143                                 /* We sent a start bit, if it was successful we can\r
 144                                 go on to send the slave address. */\r
 145                                 if( ( I2C_I2STAT == i2cSTATUS_START_TXED ) || ( I2C_I2STAT == i2cSTATUS_REP_START_TXED ) )\r
 146                                 {\r
 147                                         /* Send the slave address. */\r
 148                                         I2C_I2DAT = pxCurrentMessage->ucSlaveAddress;\r
 149 \r
 150                                         if( pxCurrentMessage->ucSlaveAddress & i2cREAD )\r
 151                                         {\r
 152                                                 /* We are then going to read bytes back from the \r
 153                                                 slave. */\r
 154                                                 eCurrentState = eSentAddressForRead;\r
 155                                                 \r
 156                                                 /* Initialise the buffer index so the first byte goes\r
 157                                                 into the first buffer position. */\r
 158                                                 lMessageIndex = 0;\r
 159                                         }\r
 160                                         else\r
 161                                         {\r
 162                                                 /* We are then going to write some data to the slave. */\r
 163                                                 eCurrentState = eSentAddressForWrite;\r
 164 \r
 165                                                 /* When writing bytes we first have to send the two\r
 166                                                 byte buffer address so lMessageIndex is set negative,\r
 167                                                 when it reaches 0 it is time to send the actual data. */\r
 168                                                 lMessageIndex = -i2cBUFFER_ADDRESS_BYTES;\r
 169                                         }\r
 170                                 }\r
 171                                 else\r
 172                                 {\r
 173                                         /* Could not send the start bit so give up. */\r
 174                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 175                                 }\r
 176 \r
 177                                 I2C_I2CONCLR = i2cSTA_BIT;                              \r
 178 \r
 179                                 break;\r
 180 \r
 181                 case eSentAddressForWrite :\r
 182 \r
 183                                 /* We sent the address of the slave we are going to write to.\r
 184                                 If this was acknowledged we     can go on to send the data. */\r
 185                                 if( I2C_I2STAT == i2cSTATUS_TX_ADDR_ACKED )\r
 186                                 {\r
 187                                         /* Start the first byte transmitting which is the \r
 188                                         first byte of the buffer address to which the data will \r
 189                                         be sent. */\r
 190                                         I2C_I2DAT = pxCurrentMessage->ucBufferAddressHighByte;\r
 191                                         eCurrentState = eSentData;\r
 192                                 }\r
 193                                 else\r
 194                                 {\r
 195                                         /* Address was not acknowledged so give up. */\r
 196                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 197                                 }                                       \r
 198                                 break;\r
 199 \r
 200                 case eSentAddressForRead :\r
 201 \r
 202                                 /* We sent the address of the slave we are going to read from.\r
 203                                 If this was acknowledged we can go on to read the data. */\r
 204                                 if( I2C_I2STAT == i2cSTATUS_RX_ADDR_ACKED )\r
 205                                 {\r
 206                                         eCurrentState = eReceiveData;\r
 207                                         if( pxCurrentMessage->lMessageLength > i2cJUST_ONE_BYTE_TO_RX )\r
 208                                         {\r
 209                                                 /* Don't ack the last byte of the message. */\r
 210                                                 I2C_I2CONSET = i2cAA_BIT;\r
 211                                         }                                       \r
 212                                 }\r
 213                                 else\r
 214                                 {\r
 215                                         /* Something unexpected happened - give up. */\r
 216                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 217                                 }\r
 218                                 break;\r
 219 \r
 220                 case eReceiveData :\r
 221                                 \r
 222                                 /* We have just received a byte from the slave. */\r
 223                                 if( ( I2C_I2STAT == i2cSTATUS_DATA_RXED ) || ( I2C_I2STAT == i2cSTATUS_LAST_BYTE_RXED ) )\r
 224                                 {\r
 225                                         /* Buffer the byte just received then increment the index \r
 226                                         so it points to the next free space. */\r
 227                                         pxCurrentMessage->pucBuffer[ lMessageIndex ] = I2C_I2DAT;\r
 228                                         lMessageIndex++;\r
 229 \r
 230                                         /* How many more bytes are we expecting to receive? */\r
 231                                         lBytesLeft = pxCurrentMessage->lMessageLength - lMessageIndex;\r
 232                                         if( lBytesLeft == ( unsigned portLONG ) 0 )\r
 233                                         {\r
 234                                                 /* This was the last byte in the message. */\r
 235                                                 i2cEND_TRANSMISSION( pdPASS );\r
 236 \r
 237                                                 /* If xMessageCompleteSemaphore is not null then there\r
 238                                                 is a task waiting for this message to complete and we\r
 239                                                 must 'give' the semaphore so the task is woken.*/\r
 240                                                 if( pxCurrentMessage->xMessageCompleteSemaphore )\r
 241                                                 {\r
 242                                                         xTaskWokenByTx = xSemaphoreGiveFromISR( pxCurrentMessage->xMessageCompleteSemaphore, xTaskWokenByTx );\r
 243                                                 }\r
 244 \r
 245                                                 /* Are there any other messages to transact? */\r
 246                                                 if( xQueueReceiveFromISR( xMessagesForTx, &pxCurrentMessage, &xTaskWokenByTx ) == pdTRUE )\r
 247                                                 {\r
 248                                                         /* Start the next message - which was\r
 249                                                         retrieved from the queue. */\r
 250                                                         I2C_I2CONSET = i2cSTA_BIT;\r
 251                                                 }\r
 252                                                 else\r
 253                                                 {\r
 254                                                         /* No more messages were found to be waiting for\r
 255                                                         transaction so the bus is free. */\r
 256                                                         ulBusFree = ( unsigned portLONG ) pdTRUE;                       \r
 257                                                 }                                               \r
 258                                         }\r
 259                                         else\r
 260                                         {\r
 261                                                 /* There are more bytes to receive but don't ack the \r
 262                                                 last byte. */\r
 263                                                 if( lBytesLeft <= i2cJUST_ONE_BYTE_TO_RX )\r
 264                                                 {\r
 265                                                         I2C_I2CONCLR = i2cAA_BIT;\r
 266                                                 }                                                        \r
 267                                         }\r
 268                                 }\r
 269                                 else\r
 270                                 {\r
 271                                         /* Something unexpected happened - give up. */\r
 272                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 273                                 }\r
 274 \r
 275                                 break;\r
 276                                 \r
 277                 case eSentData  :       \r
 278 \r
 279                                 /* We sent a data byte, if successful send the  next byte in \r
 280                                 the message. */\r
 281                                 if( I2C_I2STAT == i2cSTATUS_DATA_TXED )\r
 282                                 {\r
 283                                         /* Index to the next byte to send. */\r
 284                                         lMessageIndex++;\r
 285                                         if( lMessageIndex < 0 )\r
 286                                         {\r
 287                                                 /* lMessage index is still negative so we have so far \r
 288                                                 only sent the first byte of the buffer address.  Send \r
 289                                                 the second byte now, then initialise the buffer index\r
 290                                                 to zero so the next byte sent comes from the actual \r
 291                                                 data buffer. */\r
 292                                                 I2C_I2DAT = pxCurrentMessage->ucBufferAddressLowByte;\r
 293                                         }\r
 294                                         else if( lMessageIndex < pxCurrentMessage->lMessageLength )\r
 295                                         {\r
 296                                                 /* Simply send the next byte in the tx buffer. */\r
 297                                                 I2C_I2DAT = pxCurrentMessage->pucBuffer[ lMessageIndex ];                                                                               \r
 298                                         }\r
 299                                         else\r
 300                                         {\r
 301                                                 /* No more bytes in this message to be send.  Finished \r
 302                                                 sending message - send a stop bit. */\r
 303                                                 i2cEND_TRANSMISSION( pdPASS );\r
 304 \r
 305                                                 /* If xMessageCompleteSemaphore is not null then there\r
 306                                                 is a task waiting for this message to be sent and the\r
 307                                                 semaphore must be 'given' to wake the task. */\r
 308                                                 if( pxCurrentMessage->xMessageCompleteSemaphore )\r
 309                                                 {\r
 310                                                         xTaskWokenByTx = xSemaphoreGiveFromISR( pxCurrentMessage->xMessageCompleteSemaphore, xTaskWokenByTx );\r
 311                                                 }\r
 312 \r
 313                                                 /* Are there any other messages to transact? */\r
 314                                                 if( xQueueReceiveFromISR( xMessagesForTx, &pxCurrentMessage, &xTaskWokenByTx ) == pdTRUE )\r
 315                                                 {\r
 316                                                         /* Start the next message from the Tx queue. */\r
 317                                                         I2C_I2CONSET = i2cSTA_BIT;\r
 318                                                 }\r
 319                                                 else\r
 320                                                 {\r
 321                                                         /* No more message were queues for transaction so \r
 322                                                         the bus is free. */\r
 323                                                         ulBusFree = ( unsigned portLONG ) pdTRUE;                       \r
 324                                                 }\r
 325                                         }\r
 326                                 }\r
 327                                 else\r
 328                                 {\r
 329                                         /* Something unexpected happened, give up. */\r
 330                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 331                                 }\r
 332                                 break;\r
 333 \r
 334                 default :       \r
 335                 \r
 336                                 /* Should never get here. */\r
 337                                 eCurrentState = eSentStart;\r
 338                                 break;\r
 339         }       \r
 340 \r
 341         /* Clear the interrupt. */\r
 342         I2C_I2CONCLR = i2cSI_BIT;\r
 343         VICVectAddr = i2cCLEAR_VIC_INTERRUPT;\r
 344 \r
 345         portEXIT_SWITCHING_ISR( ( xTaskWokenByTx ) );\r
 346 }\r
 347 /*-----------------------------------------------------------*/\r
 348 \r