bertos/drv/i2c_bitbang.c

   1 /**
   2  * \file
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  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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  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         /* Clear all error, we restart */
 202         i2c->errors &= ~(I2C_NO_ACK | I2C_ARB_LOST);
 203
 204         if (old_api)
 205         {
 206                 SDA_HI;
 207                 SCL_HI;
 208                 I2C_HALFBIT_DELAY();
 209                 SDA_LO;
 210                 I2C_HALFBIT_DELAY();
 211
 212                 ret = !SDA_IN;
 213         }
 214         else
 215         {
 216                 i2c_sdaHi(I2C_DEV(i2c));
 217                 i2c_sclHi(I2C_DEV(i2c));
 218                 i2c_halfbitDelay(I2C_DEV(i2c));
 219                 i2c_sdaLo(I2C_DEV(i2c));
 220                 i2c_halfbitDelay(I2C_DEV(i2c));
 221
 222                 ret = !i2c_sdaIn(I2C_DEV(i2c));
 223         }
 224
 225         return ret;
 226 }
 227
 228
 229 static uint8_t i2c_bitbang_getc(struct I2c *i2c)
 230 {
 231         uint8_t data = 0;
 232         if (old_api)
 233         {
 234                 for (uint8_t i = 0x80; i != 0; i >>= 1)
 235                 {
 236                         SCL_LO;
 237                         I2C_HALFBIT_DELAY();
 238                         SCL_HI;
 239                         if (SDA_IN)
 240                                 data |= i;
 241                         else
 242                                 data &= ~i;
 243
 244                         I2C_HALFBIT_DELAY();
 245                 }
 246                 SCL_LO;
 247
 248                 /* Generate ACK/NACK */
 249                 if (i2c->xfer_size > 1)
 250                         SDA_LO;
 251                 else
 252                         SDA_HI;
 253
 254                 I2C_HALFBIT_DELAY();
 255                 SCL_HI;
 256                 I2C_HALFBIT_DELAY();
 257                 SCL_LO;
 258                 SDA_HI;
 259         }
 260         else
 261         {
 262                 for (uint8_t i = 0x80; i != 0; i >>= 1)
 263                 {
 264                         i2c_sclLo(I2C_DEV(i2c));
 265                         i2c_halfbitDelay(I2C_DEV(i2c));
 266                         i2c_sclHi(I2C_DEV(i2c));
 267                         if (i2c_sdaIn(I2C_DEV(i2c)))
 268                                 data |= i;
 269                         else
 270                                 data &= ~i;
 271
 272                         i2c_halfbitDelay(I2C_DEV(i2c));
 273                 }
 274                 i2c_sclLo(I2C_DEV(i2c));
 275
 276                 /* Generate ACK/NACK */
 277                 if (i2c->xfer_size > 1)
 278                         i2c_sdaLo(I2C_DEV(i2c));
 279                 else
 280                         i2c_sdaHi(I2C_DEV(i2c));
 281
 282                 i2c_halfbitDelay(I2C_DEV(i2c));
 283                 i2c_sclHi(I2C_DEV(i2c));
 284                 i2c_halfbitDelay(I2C_DEV(i2c));
 285                 i2c_sclLo(I2C_DEV(i2c));
 286                 i2c_sdaHi(I2C_DEV(i2c));
 287         }
 288
 289         /* Generate stop condition (if requested) */
 290         if ((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP))
 291                 i2c_bitbang_stop_1(i2c);
 292
 293         return data;
 294 }
 295
 296 INLINE void i2c_bitbang_putcStop(struct I2c *i2c, uint8_t _data, bool stop)
 297 {
 298         /* Add ACK bit */
 299         uint16_t data = (_data << 1) | 1;
 300         bool ack;
 301
 302         if (old_api)
 303         {
 304                 for (uint16_t i = 0x100; i != 0; i >>= 1)
 305                 {
 306                         SCL_LO;
 307                         if (data & i)
 308                                 SDA_HI;
 309                         else
 310                                 SDA_LO;
 311                         I2C_HALFBIT_DELAY();
 312
 313                         SCL_HI;
 314                         I2C_HALFBIT_DELAY();
 315                 }
 316
 317                 ack = !SDA_IN;
 318                 SCL_LO;
 319                 I2C_HALFBIT_DELAY();
 320         }
 321         else
 322         {
 323                 for (uint16_t i = 0x100; i != 0; i >>= 1)
 324                 {
 325                         i2c_sclLo(I2C_DEV(i2c));
 326                         if (data & i)
 327                                 i2c_sdaHi(I2C_DEV(i2c));
 328                         else
 329                                 i2c_sdaLo(I2C_DEV(i2c));
 330                         i2c_halfbitDelay(I2C_DEV(i2c));
 331
 332                         i2c_sclHi(I2C_DEV(i2c));
 333                         i2c_halfbitDelay(I2C_DEV(i2c));
 334                 }
 335                 ack = !i2c_sdaIn(I2C_DEV(i2c));
 336
 337                 i2c_sclLo(I2C_DEV(i2c));
 338                 i2c_halfbitDelay(I2C_DEV(i2c));
 339         }
 340
 341         if (!ack)
 342                 i2c->errors |= I2C_NO_ACK;
 343
 344         /* Generate stop condition (if requested) */
 345         if (stop || i2c->errors)
 346                 i2c_bitbang_stop_1(i2c);
 347 }
 348
 349 static void i2c_bitbang_putc(struct I2c *i2c, uint8_t data)
 350 {
 351         i2c_bitbang_putcStop(i2c, data,
 352                 (i2c->xfer_size == 1) && (i2c->flags & I2C_STOP));
 353 }
 354
 355 static void i2c_bitbang_start_2(struct I2c *i2c, uint16_t slave_addr)
 356 {
 357         if (i2c->flags & I2C_START_R)
 358                 slave_addr |= I2C_READBIT;
 359         else
 360                 slave_addr &= ~I2C_READBIT;
 361
 362         /*
 363          * Loop on the select write sequence: when the device is busy
 364          * writing previously sent data it will reply to the SLA_W
 365          * control byte with a NACK.  In this case, we must
 366          * keep trying until the device responds with an ACK.
 367          */
 368         ticks_t start = timer_clock();
 369         while (i2c_bitbang_start_1(i2c))
 370         {
 371                 i2c_bitbang_putcStop(i2c, slave_addr, false);
 372
 373                 if (!(i2c->errors & I2C_NO_ACK))
 374                         return;
 375                 else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
 376                 {
 377                         LOG_ERR("Timeout on I2C start\n");
 378                         i2c->errors |= I2C_START_TIMEOUT;
 379                         i2c_bitbang_stop_1(i2c);
 380                         return;
 381                 }
 382         }
 383
 384         LOG_ERR("START arbitration lost\n");
 385         i2c->errors |= I2C_ARB_LOST;
 386         i2c_bitbang_stop_1(i2c);
 387         return;
 388 }
 389
 390
 391 static const I2cVT i2c_bitbang_vt =
 392 {
 393         .start = i2c_bitbang_start_2,
 394         .getc = i2c_bitbang_getc,
 395         .putc = i2c_bitbang_putc,
 396         .write = i2c_genericWrite,
 397         .read = i2c_genericRead,
 398 };
 399
 400
 401 /**
 402  * Initialize i2c module.
 403  */
 404 void i2c_hw_bitbangInit(I2c *i2c, int dev)
 405 {
 406         MOD_CHECK(timer);
 407         if (dev == I2C_BITBANG_OLD)
 408                 old_api = true;
 409         else
 410                 i2c->hw = (struct I2cHardware *)(dev - I2C_BITBANG0);
 411
 412         i2c->vt = &i2c_bitbang_vt;
 413
 414         if (old_api)
 415         {
 416                 I2C_BITBANG_HW_INIT;
 417                 SDA_HI;
 418                 SCL_HI;
 419         }
 420         else
 421         {
 422                 i2c_bitbangInit(I2C_DEV(i2c));
 423                 i2c_sdaHi(I2C_DEV(i2c));
 424                 i2c_sclHi(I2C_DEV(i2c));
 425         }
 426 }
 427