bertos/drv/i2c_bitbang.c

   1 /**
   2  * \file
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  19  *
  20  * As a special exception, you may use this file as part of a free software
  21  * library without restriction.  Specifically, if other files instantiate
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  24  * file does not by itself cause the resulting executable to be covered by
  25  * the GNU General Public License.  This exception does not however
  26  * invalidate any other reasons why the executable file might be covered by
  27  * the GNU General Public License.
  28  *
  29  * Copyright 2005 Develer S.r.l. (http://www.develer.com/)
  30  *
  31  * -->
  32  *
  33  * \brief I2C bitbang driver (implementation)
  34  *
  35  * \author Francesco Sacchi <batt@develer.com>
  36  * \author Daniele Basile <asterix@develer.com>
  37  */
  38
  39 #include "hw/hw_i2c_bitbang.h"
  40
  41 #include "cfg/cfg_i2c.h"
  42
  43 #define LOG_LEVEL  I2C_LOG_LEVEL
  44 #define LOG_FORMAT I2C_LOG_FORMAT
  45
  46 #include <cfg/log.h>
  47 #include <cfg/macros.h>
  48 #include <cfg/module.h>
  49
  50 #include <drv/timer.h>
  51 #include <drv/i2c.h>
  52
  53 #include <cpu/irq.h>
  54
  55 #include <cpu/attr.h>
  56
  57 #if !CONFIG_I2C_DISABLE_OLD_API
  58
  59 INLINE bool i2c_bitbang_start(void)
  60 {
  61         SDA_HI;
  62         SCL_HI;
  63         I2C_HALFBIT_DELAY();
  64         SDA_LO;
  65         I2C_HALFBIT_DELAY();
  66
  67         return !SDA_IN;
  68 }
  69
  70 void i2c_bitbang_stop(void)
  71 {
  72         SDA_LO;
  73         SCL_HI;
  74         I2C_HALFBIT_DELAY();
  75         SDA_HI;
  76 }
  77
  78 bool i2c_bitbang_put(uint8_t _data)
  79 {
  80         /* Add ACK bit */
  81         uint16_t data = (_data << 1) | 1;
  82
  83         for (uint16_t i = 0x100; i != 0; i >>= 1)
  84         {
  85                 SCL_LO;
  86                 if (data & i)
  87                         SDA_HI;
  88                 else
  89                         SDA_LO;
  90                 I2C_HALFBIT_DELAY();
  91
  92                 SCL_HI;
  93                 I2C_HALFBIT_DELAY();
  94         }
  95
  96         bool ack = !SDA_IN;
  97         SCL_LO;
  98         I2C_HALFBIT_DELAY();
  99         return ack;
 100 }
 101
 102 bool i2c_bitbang_start_w(uint8_t id)
 103 {
 104         id &= ~I2C_READBIT;
 105         /*
 106          * Loop on the select write sequence: when the device is busy
 107          * writing previously sent data it will reply to the SLA_W
 108          * control byte with a NACK.  In this case, we must
 109          * keep trying until the deveice responds with an ACK.
 110          */
 111         ticks_t start = timer_clock();
 112         while (i2c_bitbang_start())
 113         {
 114                 if (i2c_bitbang_put(id))
 115                         return true;
 116                 else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
 117                 {
 118                         LOG_ERR("Timeout on I2C start write\n");
 119                         break;
 120                 }
 121                 //LOG_INFO("Rep start\n");
 122         }
 123
 124         return false;
 125 }
 126
 127 bool i2c_bitbang_start_r(uint8_t id)
 128 {
 129         id |= I2C_READBIT;
 130         if (i2c_bitbang_start())
 131         {
 132                 if (i2c_bitbang_put(id))
 133                         return true;
 134
 135                 LOG_ERR("NACK on I2c start read\n");
 136         }
 137
 138         return false;
 139 }
 140
 141 int i2c_bitbang_get(bool ack)
 142 {
 143         uint8_t data = 0;
 144         for (uint8_t i = 0x80; i != 0; i >>= 1)
 145         {
 146                 SCL_LO;
 147                 I2C_HALFBIT_DELAY();
 148                 SCL_HI;
 149                 if (SDA_IN)
 150                         data |= i;
 151                 else
 152                         data &= ~i;
 153
 154                 I2C_HALFBIT_DELAY();
 155         }
 156         SCL_LO;
 157
 158         if (ack)
 159                 SDA_LO;
 160         else
 161                 SDA_HI;
 162
 163         I2C_HALFBIT_DELAY();
 164         SCL_HI;
 165         I2C_HALFBIT_DELAY();
 166         SCL_LO;
 167         SDA_HI;
 168         /* avoid sign extension */
 169         return (int)(uint8_t)data;
 170 }
 171
 172 #endif /* !CONFIG_I2C_DISABLE_OLD_API */
 173
 174 /*
 175  * New I2C API
 176  */
 177 static bool old_api = false;
 178 #define I2C_DEV(i2c)            ((int)((i2c)->hw))
 179
 180 static void i2c_bitbang_stop_1(struct I2c *i2c)
 181 {
 182         if (old_api)
 183         {
 184                 SDA_LO;
 185                 SCL_HI;
 186                 I2C_HALFBIT_DELAY();
 187                 SDA_HI;
 188         }
 189         else
 190         {
 191                 i2c_sdaLo(I2C_DEV(i2c));
 192                 i2c_sclHi(I2C_DEV(i2c));
 193                 i2c_halfbitDelay(I2C_DEV(i2c));
 194                 i2c_sdaHi(I2C_DEV(i2c));
 195         }
 196 }
 197
 198 INLINE bool i2c_bitbang_start_1(struct I2c *i2c)
 199 {
 200         bool ret;
 201         if (old_api)
 202         {
 203                 SDA_HI;
 204                 SCL_HI;
 205                 I2C_HALFBIT_DELAY();
 206                 SDA_LO;
 207                 I2C_HALFBIT_DELAY();
 208
 209                 ret = !SDA_IN;
 210         }
 211         else
 212         {
 213                 i2c_sdaHi(I2C_DEV(i2c));
 214                 i2c_sclHi(I2C_DEV(i2c));
 215                 i2c_halfbitDelay(I2C_DEV(i2c));
 216                 i2c_sdaLo(I2C_DEV(i2c));
 217                 i2c_halfbitDelay(I2C_DEV(i2c));
 218                 ret = !i2c_sdaIn(I2C_DEV(i2c));
 219         }
 220
 221         return ret;
 222 }
 223
 224
 225 static uint8_t i2c_bitbang_getc(struct I2c *i2c)
 226 {
 227         uint8_t data = 0;
 228         if (old_api)
 229         {
 230                 for (uint8_t i = 0x80; i != 0; i >>= 1)
 231                 {
 232                         SCL_LO;
 233                         I2C_HALFBIT_DELAY();
 234                         SCL_HI;
 235                         if (SDA_IN)
 236                                 data |= i;
 237                         else
 238                                 data &= ~i;
 239
 240                         I2C_HALFBIT_DELAY();
 241                 }
 242                 SCL_LO;
 243
 244                 /* Generate ACK/NACK */
 245                 if (i2c->xfer_size > 1)
 246                         SDA_LO;
 247                 else
 248                         SDA_HI;
 249
 250                 I2C_HALFBIT_DELAY();
 251                 SCL_HI;
 252                 I2C_HALFBIT_DELAY();
 253                 SCL_LO;
 254                 SDA_HI;
 255         }
 256         else
 257         {
 258                 for (uint8_t i = 0x80; i != 0; i >>= 1)
 259                 {
 260                         i2c_sclLo(I2C_DEV(i2c));
 261                         i2c_halfbitDelay(I2C_DEV(i2c));
 262                         i2c_sclHi(I2C_DEV(i2c));
 263                         if (i2c_sdaIn(I2C_DEV(i2c)))
 264                                 data |= i;
 265                         else
 266                                 data &= ~i;
 267
 268                         i2c_halfbitDelay(I2C_DEV(i2c));
 269                 }
 270                 i2c_sclLo(I2C_DEV(i2c));
 271
 272                 /* Generate ACK/NACK */
 273                 if (i2c->xfer_size > 1)
 274                         i2c_sdaLo(I2C_DEV(i2c));
 275                 else
 276                         i2c_sdaHi(I2C_DEV(i2c));
 277
 278                 i2c_halfbitDelay(I2C_DEV(i2c));
 279                 i2c_sclHi(I2C_DEV(i2c));
 280                 i2c_halfbitDelay(I2C_DEV(i2c));
 281                 i2c_sclLo(I2C_DEV(i2c));
 282                 i2c_sdaHi(I2C_DEV(i2c));
 283         }
 284
 285         /* Generate stop condition (if requested) */
 286         if ((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP))
 287                 i2c_bitbang_stop_1(i2c);
 288
 289         return data;
 290 }
 291
 292 static void i2c_bitbang_putc(struct I2c *i2c, uint8_t _data)
 293 {
 294         /* Add ACK bit */
 295         uint16_t data = (_data << 1) | 1;
 296         bool ack;
 297
 298         if (old_api)
 299         {
 300                 for (uint16_t i = 0x100; i != 0; i >>= 1)
 301                 {
 302                         SCL_LO;
 303                         if (data & i)
 304                                 SDA_HI;
 305                         else
 306                                 SDA_LO;
 307                         I2C_HALFBIT_DELAY();
 308
 309                         SCL_HI;
 310                         I2C_HALFBIT_DELAY();
 311                 }
 312
 313                 ack = !SDA_IN;
 314                 SCL_LO;
 315                 I2C_HALFBIT_DELAY();
 316         }
 317         else
 318         {
 319                 for (uint16_t i = 0x100; i != 0; i >>= 1)
 320                 {
 321                         i2c_sclLo(I2C_DEV(i2c));
 322                         if (data & i)
 323                                 i2c_sdaHi(I2C_DEV(i2c));
 324                         else
 325                                 i2c_sdaLo(I2C_DEV(i2c));
 326                         i2c_halfbitDelay(I2C_DEV(i2c));
 327
 328                         i2c_sclHi(I2C_DEV(i2c));
 329                         i2c_halfbitDelay(I2C_DEV(i2c));
 330                 }
 331
 332                 ack = !i2c_sdaIn(I2C_DEV(i2c));
 333                 i2c_sclLo(I2C_DEV(i2c));
 334                 i2c_halfbitDelay(I2C_DEV(i2c));
 335         }
 336
 337         if (!ack)
 338         {
 339                 LOG_ERR("NO ACK received\n");
 340                 i2c->errors |= I2C_NO_ACK;
 341         }
 342
 343         /* Generate stop condition (if requested) */
 344         if (((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP)) || i2c->errors)
 345                 i2c_bitbang_stop_1(i2c);
 346 }
 347
 348
 349 static void i2c_bitbang_start_2(struct I2c *i2c, uint16_t slave_addr)
 350 {
 351         if (i2c->flags & I2C_START_R)
 352                 slave_addr |= I2C_READBIT;
 353         else
 354                 slave_addr &= ~I2C_READBIT;
 355
 356         /*
 357          * Loop on the select write sequence: when the device is busy
 358          * writing previously sent data it will reply to the SLA_W
 359          * control byte with a NACK.  In this case, we must
 360          * keep trying until the deveice responds with an ACK.
 361          */
 362         ticks_t start = timer_clock();
 363         while (i2c_bitbang_start_1(i2c))
 364         {
 365                 i2c_bitbang_putc(i2c, slave_addr);
 366
 367                 if (!(i2c->errors & I2C_NO_ACK))
 368                         return;
 369                 else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
 370                 {
 371                         LOG_ERR("Timeout on I2C start\n");
 372                         i2c->errors |= I2C_START_TIMEOUT;
 373                         i2c_bitbang_stop_1(i2c);
 374                         return;
 375                 }
 376         }
 377
 378         LOG_ERR("START arbitration lost\n");
 379         i2c->errors |= I2C_ARB_LOST;
 380         i2c_bitbang_stop_1(i2c);
 381         return;
 382 }
 383
 384
 385 static const I2cVT i2c_bitbang_vt =
 386 {
 387         .start = i2c_bitbang_start_2,
 388         .getc = i2c_bitbang_getc,
 389         .putc = i2c_bitbang_putc,
 390         .write = i2c_genericWrite,
 391         .read = i2c_genericRead,
 392 };
 393
 394
 395 /**
 396  * Initialize i2c module.
 397  */
 398 void i2c_hw_bitbangInit(I2c *i2c, int dev)
 399 {
 400         MOD_CHECK(timer);
 401         if (dev == I2C_BITBANG_OLD)
 402                 old_api = true;
 403         else
 404                 i2c->hw = (struct I2cHardware *)(dev - I2C_BITBANG0);
 405
 406         i2c->vt = &i2c_bitbang_vt;
 407
 408         if (old_api)
 409         {
 410                 I2C_BITBANG_HW_INIT;
 411                 SDA_HI;
 412                 SCL_HI;
 413         }
 414         else
 415         {
 416                 i2c_bitbangInit(I2C_DEV(i2c));
 417                 i2c_sdaHi(I2C_DEV(i2c));
 418                 i2c_sclHi(I2C_DEV(i2c));
 419         }
 420 }
 421