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

   1 /*\r
   2         FreeRTOS.org V4.6.0 - 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 /* The ISR entry point. */\r
 123 void vI2C_ISR_Wrapper( void ) __attribute__ (( naked ));\r
 124 \r
 125 /* The ISR function to perform the actual work.  This must be a separate\r
 126 function from the wrapper to ensure the correct stack frame is set up. */\r
 127 void vI2C_ISR_Handler( void );\r
 128 \r
 129 /*-----------------------------------------------------------*/\r
 130 \r
 131 void vI2C_ISR_Wrapper( void )\r
 132 {\r
 133         /* Save the context of the interrupted task. */\r
 134         portSAVE_CONTEXT();\r
 135 \r
 136         /* Call the handler to perform the actual work.  This must be a\r
 137         separate function to ensure the correct stack frame is set up. */\r
 138         vI2C_ISR_Handler();\r
 139 \r
 140         /* Restore the context of whichever task is going to run next. */\r
 141         portRESTORE_CONTEXT();\r
 142 }\r
 143 /*-----------------------------------------------------------*/\r
 144 \r
 145 void vI2C_ISR_Handler( void )\r
 146 {\r
 147 /* Holds the current transmission state. */                                                     \r
 148 static I2C_STATE eCurrentState = eSentStart;\r
 149 static portLONG lMessageIndex = -i2cBUFFER_ADDRESS_BYTES; /* There are two address bytes to send prior to the data. */\r
 150 portBASE_TYPE xTaskWokenByTx = pdFALSE;\r
 151 portLONG lBytesLeft;\r
 152 \r
 153         /* The action taken for this interrupt depends on our current state. */\r
 154         switch( eCurrentState )\r
 155         {\r
 156                 case eSentStart :       \r
 157 \r
 158                                 /* We sent a start bit, if it was successful we can\r
 159                                 go on to send the slave address. */\r
 160                                 if( ( I2C_I2STAT == i2cSTATUS_START_TXED ) || ( I2C_I2STAT == i2cSTATUS_REP_START_TXED ) )\r
 161                                 {\r
 162                                         /* Send the slave address. */\r
 163                                         I2C_I2DAT = pxCurrentMessage->ucSlaveAddress;\r
 164 \r
 165                                         if( pxCurrentMessage->ucSlaveAddress & i2cREAD )\r
 166                                         {\r
 167                                                 /* We are then going to read bytes back from the \r
 168                                                 slave. */\r
 169                                                 eCurrentState = eSentAddressForRead;\r
 170                                                 \r
 171                                                 /* Initialise the buffer index so the first byte goes\r
 172                                                 into the first buffer position. */\r
 173                                                 lMessageIndex = 0;\r
 174                                         }\r
 175                                         else\r
 176                                         {\r
 177                                                 /* We are then going to write some data to the slave. */\r
 178                                                 eCurrentState = eSentAddressForWrite;\r
 179 \r
 180                                                 /* When writing bytes we first have to send the two\r
 181                                                 byte buffer address so lMessageIndex is set negative,\r
 182                                                 when it reaches 0 it is time to send the actual data. */\r
 183                                                 lMessageIndex = -i2cBUFFER_ADDRESS_BYTES;\r
 184                                         }\r
 185                                 }\r
 186                                 else\r
 187                                 {\r
 188                                         /* Could not send the start bit so give up. */\r
 189                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 190                                 }\r
 191 \r
 192                                 I2C_I2CONCLR = i2cSTA_BIT;                              \r
 193 \r
 194                                 break;\r
 195 \r
 196                 case eSentAddressForWrite :\r
 197 \r
 198                                 /* We sent the address of the slave we are going to write to.\r
 199                                 If this was acknowledged we     can go on to send the data. */\r
 200                                 if( I2C_I2STAT == i2cSTATUS_TX_ADDR_ACKED )\r
 201                                 {\r
 202                                         /* Start the first byte transmitting which is the \r
 203                                         first byte of the buffer address to which the data will \r
 204                                         be sent. */\r
 205                                         I2C_I2DAT = pxCurrentMessage->ucBufferAddressHighByte;\r
 206                                         eCurrentState = eSentData;\r
 207                                 }\r
 208                                 else\r
 209                                 {\r
 210                                         /* Address was not acknowledged so give up. */\r
 211                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 212                                 }                                       \r
 213                                 break;\r
 214 \r
 215                 case eSentAddressForRead :\r
 216 \r
 217                                 /* We sent the address of the slave we are going to read from.\r
 218                                 If this was acknowledged we can go on to read the data. */\r
 219                                 if( I2C_I2STAT == i2cSTATUS_RX_ADDR_ACKED )\r
 220                                 {\r
 221                                         eCurrentState = eReceiveData;\r
 222                                         if( pxCurrentMessage->lMessageLength > i2cJUST_ONE_BYTE_TO_RX )\r
 223                                         {\r
 224                                                 /* Don't ack the last byte of the message. */\r
 225                                                 I2C_I2CONSET = i2cAA_BIT;\r
 226                                         }                                       \r
 227                                 }\r
 228                                 else\r
 229                                 {\r
 230                                         /* Something unexpected happened - give up. */\r
 231                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 232                                 }\r
 233                                 break;\r
 234 \r
 235                 case eReceiveData :\r
 236                                 \r
 237                                 /* We have just received a byte from the slave. */\r
 238                                 if( ( I2C_I2STAT == i2cSTATUS_DATA_RXED ) || ( I2C_I2STAT == i2cSTATUS_LAST_BYTE_RXED ) )\r
 239                                 {\r
 240                                         /* Buffer the byte just received then increment the index \r
 241                                         so it points to the next free space. */\r
 242                                         pxCurrentMessage->pucBuffer[ lMessageIndex ] = I2C_I2DAT;\r
 243                                         lMessageIndex++;\r
 244 \r
 245                                         /* How many more bytes are we expecting to receive? */\r
 246                                         lBytesLeft = pxCurrentMessage->lMessageLength - lMessageIndex;\r
 247                                         if( lBytesLeft == ( unsigned portLONG ) 0 )\r
 248                                         {\r
 249                                                 /* This was the last byte in the message. */\r
 250                                                 i2cEND_TRANSMISSION( pdPASS );\r
 251 \r
 252                                                 /* If xMessageCompleteSemaphore is not null then there\r
 253                                                 is a task waiting for this message to complete and we\r
 254                                                 must 'give' the semaphore so the task is woken.*/\r
 255                                                 if( pxCurrentMessage->xMessageCompleteSemaphore )\r
 256                                                 {\r
 257                                                         xTaskWokenByTx = xSemaphoreGiveFromISR( pxCurrentMessage->xMessageCompleteSemaphore, xTaskWokenByTx );\r
 258                                                 }\r
 259 \r
 260                                                 /* Are there any other messages to transact? */\r
 261                                                 if( xQueueReceiveFromISR( xMessagesForTx, &pxCurrentMessage, &xTaskWokenByTx ) == pdTRUE )\r
 262                                                 {\r
 263                                                         /* Start the next message - which was\r
 264                                                         retrieved from the queue. */\r
 265                                                         I2C_I2CONSET = i2cSTA_BIT;\r
 266                                                 }\r
 267                                                 else\r
 268                                                 {\r
 269                                                         /* No more messages were found to be waiting for\r
 270                                                         transaction so the bus is free. */\r
 271                                                         ulBusFree = ( unsigned portLONG ) pdTRUE;                       \r
 272                                                 }                                               \r
 273                                         }\r
 274                                         else\r
 275                                         {\r
 276                                                 /* There are more bytes to receive but don't ack the \r
 277                                                 last byte. */\r
 278                                                 if( lBytesLeft <= i2cJUST_ONE_BYTE_TO_RX )\r
 279                                                 {\r
 280                                                         I2C_I2CONCLR = i2cAA_BIT;\r
 281                                                 }                                                        \r
 282                                         }\r
 283                                 }\r
 284                                 else\r
 285                                 {\r
 286                                         /* Something unexpected happened - give up. */\r
 287                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 288                                 }\r
 289 \r
 290                                 break;\r
 291                                 \r
 292                 case eSentData  :       \r
 293 \r
 294                                 /* We sent a data byte, if successful send the  next byte in \r
 295                                 the message. */\r
 296                                 if( I2C_I2STAT == i2cSTATUS_DATA_TXED )\r
 297                                 {\r
 298                                         /* Index to the next byte to send. */\r
 299                                         lMessageIndex++;\r
 300                                         if( lMessageIndex < 0 )\r
 301                                         {\r
 302                                                 /* lMessage index is still negative so we have so far \r
 303                                                 only sent the first byte of the buffer address.  Send \r
 304                                                 the second byte now, then initialise the buffer index\r
 305                                                 to zero so the next byte sent comes from the actual \r
 306                                                 data buffer. */\r
 307                                                 I2C_I2DAT = pxCurrentMessage->ucBufferAddressLowByte;\r
 308                                         }\r
 309                                         else if( lMessageIndex < pxCurrentMessage->lMessageLength )\r
 310                                         {\r
 311                                                 /* Simply send the next byte in the tx buffer. */\r
 312                                                 I2C_I2DAT = pxCurrentMessage->pucBuffer[ lMessageIndex ];                                                                               \r
 313                                         }\r
 314                                         else\r
 315                                         {\r
 316                                                 /* No more bytes in this message to be send.  Finished \r
 317                                                 sending message - send a stop bit. */\r
 318                                                 i2cEND_TRANSMISSION( pdPASS );\r
 319 \r
 320                                                 /* If xMessageCompleteSemaphore is not null then there\r
 321                                                 is a task waiting for this message to be sent and the\r
 322                                                 semaphore must be 'given' to wake the task. */\r
 323                                                 if( pxCurrentMessage->xMessageCompleteSemaphore )\r
 324                                                 {\r
 325                                                         xTaskWokenByTx = xSemaphoreGiveFromISR( pxCurrentMessage->xMessageCompleteSemaphore, xTaskWokenByTx );\r
 326                                                 }\r
 327 \r
 328                                                 /* Are there any other messages to transact? */\r
 329                                                 if( xQueueReceiveFromISR( xMessagesForTx, &pxCurrentMessage, &xTaskWokenByTx ) == pdTRUE )\r
 330                                                 {\r
 331                                                         /* Start the next message from the Tx queue. */\r
 332                                                         I2C_I2CONSET = i2cSTA_BIT;\r
 333                                                 }\r
 334                                                 else\r
 335                                                 {\r
 336                                                         /* No more message were queues for transaction so \r
 337                                                         the bus is free. */\r
 338                                                         ulBusFree = ( unsigned portLONG ) pdTRUE;                       \r
 339                                                 }\r
 340                                         }\r
 341                                 }\r
 342                                 else\r
 343                                 {\r
 344                                         /* Something unexpected happened, give up. */\r
 345                                         i2cEND_TRANSMISSION( pdFAIL );                                  \r
 346                                 }\r
 347                                 break;\r
 348 \r
 349                 default :       \r
 350                 \r
 351                                 /* Should never get here. */\r
 352                                 eCurrentState = eSentStart;\r
 353                                 break;\r
 354         }       \r
 355 \r
 356         /* Clear the interrupt. */\r
 357         I2C_I2CONCLR = i2cSI_BIT;\r
 358         VICVectAddr = i2cCLEAR_VIC_INTERRUPT;\r
 359 \r
 360         if( xTaskWokenByTx )\r
 361         {\r
 362                 portYIELD_FROM_ISR();\r
 363         }\r
 364 }\r
 365 /*-----------------------------------------------------------*/\r
 366 \r