bertos/drv/i2c_bitbang.c

   1 /**
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  25  * the GNU General Public License.  This exception does not however
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  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 MOD_DEFINE(i2c);
 173
 174 /**
 175  * Initialize i2c module.
 176  */
 177 void i2c_bitbang_init(void)
 178 {
 179         MOD_CHECK(timer);
 180         I2C_BITBANG_HW_INIT;
 181         SDA_HI;
 182         SCL_HI;
 183         MOD_INIT(i2c);
 184 }
 185 #endif /* !CONFIG_I2C_DISABLE_OLD_API */
 186
 187 /*
 188  * New I2C API
 189  */
 190 #define I2C_DEV(i2c)            ((int)((i2c)->hw))
 191
 192 static void i2c_bitbang_stop_1(struct I2c *i2c)
 193 {
 194         i2c_sdaLo(I2C_DEV(i2c));
 195         i2c_sclHi(I2C_DEV(i2c));
 196         i2c_halfbitDelay(I2C_DEV(i2c));
 197         i2c_sdaHi(I2C_DEV(i2c));
 198 }
 199
 200 INLINE bool i2c_bitbang_start_1(struct I2c *i2c)
 201 {
 202         i2c_sdaHi(I2C_DEV(i2c));
 203         i2c_sclHi(I2C_DEV(i2c));
 204         i2c_halfbitDelay(I2C_DEV(i2c));
 205         i2c_sdaLo(I2C_DEV(i2c));
 206         i2c_halfbitDelay(I2C_DEV(i2c));
 207
 208         return !i2c_sdaIn(I2C_DEV(i2c));
 209 }
 210
 211
 212 static uint8_t i2c_bitbang_getc(struct I2c *i2c)
 213 {
 214         uint8_t data = 0;
 215         for (uint8_t i = 0x80; i != 0; i >>= 1)
 216         {
 217                 i2c_sclLo(I2C_DEV(i2c));
 218                 i2c_halfbitDelay(I2C_DEV(i2c));
 219                 i2c_sclHi(I2C_DEV(i2c));
 220                 if (i2c_sdaIn(I2C_DEV(i2c)))
 221                         data |= i;
 222                 else
 223                         data &= ~i;
 224
 225                 i2c_halfbitDelay(I2C_DEV(i2c));
 226         }
 227         i2c_sclLo(I2C_DEV(i2c));
 228
 229         /* Generate ACK/NACK */
 230         if (i2c->xfer_size > 1)
 231                 i2c_sdaLo(I2C_DEV(i2c));
 232         else
 233                 i2c_sdaHi(I2C_DEV(i2c));
 234
 235         i2c_halfbitDelay(I2C_DEV(i2c));
 236         i2c_sclHi(I2C_DEV(i2c));
 237         i2c_halfbitDelay(I2C_DEV(i2c));
 238         i2c_sclLo(I2C_DEV(i2c));
 239         i2c_sdaHi(I2C_DEV(i2c));
 240
 241         /* Generate stop condition (if requested) */
 242         if ((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP))
 243                 i2c_bitbang_stop_1(i2c);
 244
 245         return data;
 246 }
 247
 248 static void i2c_bitbang_putc(struct I2c *i2c, uint8_t _data)
 249 {
 250         /* Add ACK bit */
 251         uint16_t data = (_data << 1) | 1;
 252
 253         for (uint16_t i = 0x100; i != 0; i >>= 1)
 254         {
 255                 i2c_sclLo(I2C_DEV(i2c));
 256                 if (data & i)
 257                         i2c_sdaHi(I2C_DEV(i2c));
 258                 else
 259                         i2c_sdaLo(I2C_DEV(i2c));
 260                 i2c_halfbitDelay(I2C_DEV(i2c));
 261
 262                 i2c_sclHi(I2C_DEV(i2c));
 263                 i2c_halfbitDelay(I2C_DEV(i2c));
 264         }
 265
 266         bool ack = !i2c_sdaIn(I2C_DEV(i2c));
 267         i2c_sclLo(I2C_DEV(i2c));
 268         i2c_halfbitDelay(I2C_DEV(i2c));
 269
 270         if (!ack)
 271         {
 272                 LOG_ERR("NO ACK received\n");
 273                 i2c->errors |= I2C_NO_ACK;
 274         }
 275
 276         /* Generate stop condition (if requested) */
 277         if (((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP)) || i2c->errors)
 278                 i2c_bitbang_stop_1(i2c);
 279 }
 280
 281
 282 static void i2c_bitbang_start_2(struct I2c *i2c, uint16_t slave_addr)
 283 {
 284         if (i2c->flags & I2C_START_R)
 285                 slave_addr |= I2C_READBIT;
 286         else
 287                 slave_addr &= ~I2C_READBIT;
 288
 289         /*
 290          * Loop on the select write sequence: when the device is busy
 291          * writing previously sent data it will reply to the SLA_W
 292          * control byte with a NACK.  In this case, we must
 293          * keep trying until the deveice responds with an ACK.
 294          */
 295         ticks_t start = timer_clock();
 296         while (i2c_bitbang_start_1(i2c))
 297         {
 298                 i2c_bitbang_putc(i2c, slave_addr);
 299
 300                 if (!(i2c->errors & I2C_NO_ACK))
 301                         return;
 302                 else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
 303                 {
 304                         LOG_ERR("Timeout on I2C start\n");
 305                         i2c->errors |= I2C_START_TIMEOUT;
 306                         i2c_bitbang_stop_1(i2c);
 307                         return;
 308                 }
 309         }
 310
 311         LOG_ERR("START arbitration lost\n");
 312         i2c->errors |= I2C_ARB_LOST;
 313         i2c_bitbang_stop_1(i2c);
 314         return;
 315 }
 316
 317
 318 static const I2cVT i2c_bitbang_vt =
 319 {
 320         .start = i2c_bitbang_start_2,
 321         .getc = i2c_bitbang_getc,
 322         .putc = i2c_bitbang_putc,
 323         .write = i2c_genericWrite,
 324         .read = i2c_genericRead,
 325 };
 326
 327
 328 /**
 329  * Initialize i2c module.
 330  */
 331 void i2c_hw_bitbangInit(I2c *i2c, int dev)
 332 {
 333         MOD_CHECK(timer);
 334         i2c->hw = (struct I2cHardware *)(dev - I2C_BITBANG0);
 335         i2c->vt = &i2c_bitbang_vt;
 336
 337         i2c_bitbang_init(I2C_DEV(i2c));
 338         i2c_sdaHi(I2C_DEV(i2c));
 339         i2c_sclHi(I2C_DEV(i2c));
 340 }
 341