core/i2c/i2c.c

   1 /*****************************************************************************
   2  *   i2c.c:  I2C C file for NXP LPC11xx/13xx Family Microprocessors
   3  *
   4  *   Copyright(C) 2008, NXP Semiconductor
   5  *   Parts of this code are (C) 2010, MyVoice CAD/CAM Services
   6  *   All rights reserved.
   7  *
   8  *   History
   9  *   2009.12.07  ver 1.00    Preliminary version, first Release
  10  *   2010.07.19  ver 1.10    Rob Jansen - MyVoice CAD/CAM Services:
  11  *                           Major cleaning and a rewrite of some functions
  12  *                           - adding ACK/NACK handling to the state machine
  13  *                           - adding a return result to the I2CEngine()
  14  *
  15 *****************************************************************************/
  16 #include "i2c.h"
  17
  18 volatile uint32_t I2CMasterState = I2CSTATE_IDLE;
  19 volatile uint32_t I2CSlaveState = I2CSTATE_IDLE;
  20
  21 volatile uint8_t I2CMasterBuffer[I2C_BUFSIZE];
  22 volatile uint8_t I2CSlaveBuffer[I2C_BUFSIZE];
  23 volatile uint32_t I2CReadLength;
  24 volatile uint32_t I2CWriteLength;
  25
  26 volatile uint32_t RdIndex = 0;
  27 volatile uint32_t WrIndex = 0;
  28
  29
  30 /*****************************************************************************
  31 ** Function name:               I2C_IRQHandler
  32 **
  33 ** Descriptions:                I2C interrupt handler, deal with master mode only.
  34 **
  35 ** parameters:                  None
  36 ** Returned value:              None
  37 **
  38 *****************************************************************************/
  39 void I2C_IRQHandler(void)
  40 {
  41         uint8_t StatValue;
  42
  43         /* this handler deals with master read and master write only */
  44         StatValue = I2C_I2CSTAT;
  45         switch ( StatValue )
  46         {
  47         case 0x08:
  48                 /*
  49                  * A START condition has been transmitted.
  50                  * We now send the slave address and initialize
  51                  * the write buffer
  52                  * (we always start with a write after START+SLA)
  53                  */
  54                 WrIndex = 0;
  55                 I2C_I2CDAT = I2CMasterBuffer[WrIndex++];
  56                 I2C_I2CCONCLR = (I2CONCLR_SIC | I2CONCLR_STAC);
  57                 I2CMasterState = I2CSTATE_PENDING;
  58                 break;
  59
  60         case 0x10:
  61                 /*
  62                  * A repeated START condition has been transmitted.
  63                  * Now a second, read, transaction follows so we
  64                  * initialize the read buffer.
  65                  */
  66                 RdIndex = 0;
  67                 /* Send SLA with R bit set, */
  68                 I2C_I2CDAT = I2CMasterBuffer[WrIndex++];
  69                 I2C_I2CCONCLR = (I2CONCLR_SIC | I2CONCLR_STAC);
  70         break;
  71
  72         case 0x18:
  73                 /*
  74                  * SLA+W has been transmitted; ACK has been received.
  75                  * We now start writing bytes.
  76                  */
  77                 I2C_I2CDAT = I2CMasterBuffer[WrIndex++];
  78                 I2C_I2CCONCLR = I2CONCLR_SIC;
  79                 break;
  80
  81         case 0x20:
  82                 /*
  83                  * SLA+W has been transmitted; NOT ACK has been received.
  84                  * Send a stop condition to terminate the transaction
  85                  * and signal I2CEngine the transaction is aborted.
  86                  */
  87                 I2C_I2CCONSET = I2CONSET_STO;
  88                 I2C_I2CCONCLR = I2CONCLR_SIC;
  89                 I2CMasterState = I2CSTATE_SLA_NACK;
  90                 break;
  91
  92         case 0x28:
  93                 /*
  94                  * Data in I2DAT has been transmitted; ACK has been received.
  95                  * Continue sending more bytes as long as there are bytes to send
  96                  * and after this check if a read transaction should follow.
  97                  */
  98                 if ( WrIndex < I2CWriteLength )
  99                 {
 100                         /* Keep writing as long as bytes avail */
 101                         I2C_I2CDAT = I2CMasterBuffer[WrIndex++];
 102                 }
 103                 else
 104                 {
 105                         if ( I2CReadLength != 0 )
 106                         {
 107                                 /* Send a Repeated START to initialize a read transaction */
 108                                 /* (handled in state 0x10)                                */
 109                                 I2C_I2CCONSET = I2CONSET_STA;   /* Set Repeated-start flag */
 110                         }
 111                         else
 112                         {
 113                                 I2CMasterState = I2CSTATE_ACK;
 114                                 I2C_I2CCONSET = I2CONSET_STO;      /* Set Stop flag */
 115                         }
 116                 }
 117                 I2C_I2CCONCLR = I2CONCLR_SIC;
 118                 break;
 119
 120         case 0x30:
 121                 /*
 122                  * Data byte in I2DAT has been transmitted; NOT ACK has been received
 123                  * Send a STOP condition to terminate the transaction and inform the
 124                  * I2CEngine that the transaction failed.
 125                  */
 126                 I2C_I2CCONSET = I2CONSET_STO;
 127                 I2C_I2CCONCLR = I2CONCLR_SIC;
 128                 I2CMasterState = I2CSTATE_NACK;
 129                 break;
 130
 131         case 0x38:
 132                 /*
 133                  * Arbitration loss in SLA+R/W or Data bytes.
 134                  * This is a fatal condition, the transaction did not complete due
 135                  * to external reasons (e.g. hardware system failure).
 136                  * Inform the I2CEngine of this and cancel the transaction
 137                  * (this is automatically done by the I2C hardware)
 138                  */
 139                 I2CMasterState = I2CSTATE_ARB_LOSS;
 140                 I2C_I2CCONCLR = I2CONCLR_SIC;
 141                 break;
 142
 143         case 0x40:
 144                 /*
 145                  * SLA+R has been transmitted; ACK has been received.
 146                  * Initialize a read.
 147                  * Since a NOT ACK is sent after reading the last byte,
 148                  * we need to prepare a NOT ACK in case we only read 1 byte.
 149                  */
 150                 if ( I2CReadLength == 1 )
 151                 {
 152                         /* last (and only) byte: send a NACK after data is received */
 153                         I2C_I2CCONCLR = I2CONCLR_AAC;
 154                 }
 155                 else
 156                 {
 157                         /* more bytes to follow: send an ACK after data is received */
 158                         I2C_I2CCONSET = I2CONSET_AA;
 159                 }
 160                 I2C_I2CCONCLR = I2CONCLR_SIC;
 161                 break;
 162
 163         case 0x48:
 164                 /*
 165                  * SLA+R has been transmitted; NOT ACK has been received.
 166                  * Send a stop condition to terminate the transaction
 167                  * and signal I2CEngine the transaction is aborted.
 168                  */
 169                 I2C_I2CCONSET = I2CONSET_STO;
 170                 I2C_I2CCONCLR = I2CONCLR_SIC;
 171                 I2CMasterState = I2CSTATE_SLA_NACK;
 172                 break;
 173
 174         case 0x50:
 175                 /*
 176                  * Data byte has been received; ACK has been returned.
 177                  * Read the byte and check for more bytes to read.
 178                  * Send a NOT ACK after the last byte is received
 179                  */
 180                 I2CSlaveBuffer[RdIndex++] = I2C_I2CDAT;
 181                 if ( RdIndex < (I2CReadLength-1) )
 182                 {
 183                         /* lmore bytes to follow: send an ACK after data is received */
 184                         I2C_I2CCONSET = I2CONSET_AA;
 185                 }
 186                 else
 187                 {
 188                         /* last byte: send a NACK after data is received */
 189                         I2C_I2CCONCLR = I2CONCLR_AAC;
 190                 }
 191                 I2C_I2CCONCLR = I2CONCLR_SIC;
 192                 break;
 193
 194         case 0x58:
 195                 /*
 196                  * Data byte has been received; NOT ACK has been returned.
 197                  * This is the last byte to read.
 198                  * Generate a STOP condition and flag the I2CEngine that the
 199                  * transaction is finished.
 200                  */
 201                 I2CSlaveBuffer[RdIndex++] = I2C_I2CDAT;
 202                 I2CMasterState = I2CSTATE_ACK;
 203                 I2C_I2CCONSET = I2CONSET_STO;   /* Set Stop flag */
 204                 I2C_I2CCONCLR = I2CONCLR_SIC;   /* Clear SI flag */
 205                 break;
 206
 207
 208         default:
 209                 I2C_I2CCONCLR = I2CONCLR_SIC;
 210         break;
 211   }
 212   return;
 213 }
 214
 215 /*****************************************************************************
 216 ** Function name:       I2CStart
 217 **
 218 ** Descriptions:        Create I2C start condition, a timeout
 219 **                                      value is set if the I2C never gets started,
 220 **                                      and timed out. It's a fatal error.
 221 **
 222 ** parameters:          None
 223 ** Returned value:      true or false, return false if timed out
 224 **
 225 *****************************************************************************/
 226 static uint32_t I2CStart( void )
 227 {
 228         uint32_t timeout = 0;
 229
 230         /*--- Issue a start condition ---*/
 231         I2C_I2CCONSET = I2CONSET_STA;   /* Set Start flag */
 232
 233         while((I2CMasterState != I2CSTATE_PENDING) && (timeout < MAX_TIMEOUT))
 234         {
 235                 timeout++;
 236         }
 237
 238         return (timeout < MAX_TIMEOUT);
 239 }
 240
 241 /*****************************************************************************
 242 ** Function name:       I2CStop
 243 **
 244 ** Descriptions:        Set the I2C stop condition
 245 **
 246 ** parameters:          None
 247 ** Returned value:      true or never return
 248 **
 249 *****************************************************************************/
 250 static uint32_t I2CStop( void )
 251 {
 252         uint32_t timeout = 0;
 253
 254         I2C_I2CCONSET = I2CONSET_STO;      /* Set Stop flag */
 255         I2C_I2CCONCLR = I2CONCLR_SIC;  /* Clear SI flag */
 256
 257         /*--- Wait for STOP detected ---*/
 258         while((I2C_I2CCONSET & I2CONSET_STO) && (timeout < MAX_TIMEOUT))
 259         {
 260                 timeout++;
 261         }
 262         return (timeout >= MAX_TIMEOUT);
 263 }
 264
 265 /*****************************************************************************
 266 ** Function name:       I2CInit
 267 **
 268 ** Descriptions:        Initialize I2C controller
 269 **
 270 ** parameters:          I2c mode is either MASTER or SLAVE
 271 ** Returned value:      true or false, return false if the I2C
 272 **                                      interrupt handler was not installed correctly
 273 **
 274 *****************************************************************************/
 275 uint32_t i2cInit( uint32_t I2cMode )
 276 {
 277         SCB_PRESETCTRL |= (0x1<<1);
 278
 279   // Enable I2C clock
 280   SCB_SYSAHBCLKCTRL |= (SCB_SYSAHBCLKCTRL_I2C);
 281
 282   // Configure pin 0.4 for SCL
 283   IOCON_PIO0_4 &= ~(IOCON_PIO0_4_FUNC_MASK | IOCON_PIO0_4_I2CMODE_MASK);
 284   IOCON_PIO0_4 |= (IOCON_PIO0_4_FUNC_I2CSCL);
 285
 286   // Configure pin 0.5 for SDA
 287   IOCON_PIO0_5 &= ~(IOCON_PIO0_5_FUNC_MASK | IOCON_PIO0_5_I2CMODE_MASK);
 288   IOCON_PIO0_5 |= IOCON_PIO0_5_FUNC_I2CSDA;
 289
 290   // Clear flags
 291   I2C_I2CCONCLR = I2C_I2CCONCLR_AAC |
 292                   I2C_I2CCONCLR_SIC |
 293                   I2C_I2CCONCLR_STAC |
 294                   I2C_I2CCONCLR_I2ENC;
 295
 296   // See p.128 for appropriate values for SCLL and SCLH
 297 #if I2C_FAST_MODE_PLUS
 298   IOCON_PIO0_4 |= (IOCON_PIO0_4_I2CMODE_FASTPLUSI2C);
 299   IOCON_PIO0_5 |= (IOCON_PIO0_5_I2CMODE_FASTPLUSI2C);
 300   I2C_I2CSCLL   = I2C_SCLL_HS_SCLL;
 301   I2C_I2CSCLH   = I2C_SCLH_HS_SCLH;
 302 #else
 303   I2C_I2CSCLL   = I2SCLL_SCLL;
 304   I2C_I2CSCLH   = I2SCLH_SCLH;
 305 #endif
 306
 307   if ( I2cMode == I2CSLAVE )
 308   {
 309     I2C_I2CADR0 = SLAVE_ADDR;
 310   }
 311
 312   /* Enable the I2C Interrupt */
 313   NVIC_EnableIRQ(I2C_IRQn);
 314   I2C_I2CCONSET = I2C_I2CCONSET_I2EN;
 315
 316   return( TRUE );
 317 }
 318
 319 /*****************************************************************************
 320 ** Function name:       I2CEngine
 321 **
 322 ** Descriptions:        The routine to complete a I2C transaction
 323 **                                      from start to stop. All the intermitten
 324 **                                      steps are handled in the interrupt handler.
 325 **                                      Before this routine is called, the read
 326 **                                      length, write length and I2C master buffer
 327 **                                      need to be filled.
 328 **
 329 ** parameters:          None
 330 ** Returned value:      Any of the I2CSTATE_... values. See i2c.h
 331 **
 332 *****************************************************************************/
 333 uint32_t i2cEngine( void )
 334 {
 335   I2CMasterState = I2CSTATE_IDLE;
 336   RdIndex = 0;
 337   WrIndex = 0;
 338   if ( I2CStart() != TRUE )
 339   {
 340         I2CStop();
 341         return ( FALSE );
 342   }
 343
 344   /* wait until the state is a terminal state */
 345   while (I2CMasterState < 0x100);
 346
 347   return ( I2CMasterState );
 348 }
 349
 350 /******************************************************************************
 351 **                            End Of File
 352 ******************************************************************************/
 353