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
  58 INLINE bool i2c_bitbang_start(void)
  59 {
  60         SDA_HI;
  61         SCL_HI;
  62         I2C_HALFBIT_DELAY();
  63         SDA_LO;
  64         I2C_HALFBIT_DELAY();
  65
  66         return !SDA_IN;
  67 }
  68
  69 void i2c_bitbang_stop(void)
  70 {
  71         SDA_LO;
  72         SCL_HI;
  73         I2C_HALFBIT_DELAY();
  74         SDA_HI;
  75 }
  76
  77 bool i2c_bitbang_put(uint8_t _data)
  78 {
  79         /* Add ACK bit */
  80         uint16_t data = (_data << 1) | 1;
  81
  82         for (uint16_t i = 0x100; i != 0; i >>= 1)
  83         {
  84                 SCL_LO;
  85                 if (data & i)
  86                         SDA_HI;
  87                 else
  88                         SDA_LO;
  89                 I2C_HALFBIT_DELAY();
  90
  91                 SCL_HI;
  92                 I2C_HALFBIT_DELAY();
  93         }
  94
  95         bool ack = !SDA_IN;
  96         SCL_LO;
  97         I2C_HALFBIT_DELAY();
  98         return ack;
  99 }
 100
 101 bool i2c_bitbang_start_w(uint8_t id)
 102 {
 103         id &= ~I2C_READBIT;
 104         /*
 105          * Loop on the select write sequence: when the device is busy
 106          * writing previously sent data it will reply to the SLA_W
 107          * control byte with a NACK.  In this case, we must
 108          * keep trying until the deveice responds with an ACK.
 109          */
 110         ticks_t start = timer_clock();
 111         while (i2c_bitbang_start())
 112         {
 113                 if (i2c_bitbang_put(id))
 114                         return true;
 115                 else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
 116                 {
 117                         LOG_ERR("Timeout on I2C start write\n");
 118                         break;
 119                 }
 120                 //LOG_INFO("Rep start\n");
 121         }
 122
 123         return false;
 124 }
 125
 126 bool i2c_bitbang_start_r(uint8_t id)
 127 {
 128         id |= I2C_READBIT;
 129         if (i2c_bitbang_start())
 130         {
 131                 if (i2c_bitbang_put(id))
 132                         return true;
 133
 134                 LOG_ERR("NACK on I2c start read\n");
 135         }
 136
 137         return false;
 138 }
 139
 140 int i2c_bitbang_get(bool ack)
 141 {
 142         uint8_t data = 0;
 143         for (uint8_t i = 0x80; i != 0; i >>= 1)
 144         {
 145                 SCL_LO;
 146                 I2C_HALFBIT_DELAY();
 147                 SCL_HI;
 148                 if (SDA_IN)
 149                         data |= i;
 150                 else
 151                         data &= ~i;
 152
 153                 I2C_HALFBIT_DELAY();
 154         }
 155         SCL_LO;
 156
 157         if (ack)
 158                 SDA_LO;
 159         else
 160                 SDA_HI;
 161
 162         I2C_HALFBIT_DELAY();
 163         SCL_HI;
 164         I2C_HALFBIT_DELAY();
 165         SCL_LO;
 166         SDA_HI;
 167         /* avoid sign extension */
 168         return (int)(uint8_t)data;
 169 }
 170
 171 MOD_DEFINE(i2c);
 172
 173 /**
 174  * Initialize i2c module.
 175  */
 176 void i2c_bitbang_init(void)
 177 {
 178         MOD_CHECK(timer);
 179         I2C_BITBANG_HW_INIT;
 180         SDA_HI;
 181         SCL_HI;
 182         MOD_INIT(i2c);
 183 }
 184
 185
 186 /*
 187  * New I2C API
 188  */
 189 #define I2C_DEV(i2c)            ((int)((i2c)->hw))
 190
 191 static void i2c_bitbang_stop_1(struct I2c *i2c)
 192 {
 193         i2c_hw_sdaLo(I2C_DEV(i2c));
 194         i2c_hw_sclHi(I2C_DEV(i2c));
 195         i2c_hw_halfbitDelay(I2C_DEV(i2c));
 196         i2c_hw_sdaHi(I2C_DEV(i2c));
 197 }
 198
 199 INLINE bool i2c_bitbang_start_1(struct I2c *i2c)
 200 {
 201         i2c_hw_sdaHi(I2C_DEV(i2c));
 202         i2c_hw_sclHi(I2C_DEV(i2c));
 203         i2c_hw_halfbitDelay(I2C_DEV(i2c));
 204         i2c_hw_sdaLo(I2C_DEV(i2c));
 205         i2c_hw_halfbitDelay(I2C_DEV(i2c));
 206
 207         return !i2c_hw_sdaIn(I2C_DEV(i2c));
 208 }
 209
 210
 211 static uint8_t i2c_bitbang_getc(struct I2c *i2c)
 212 {
 213         uint8_t data = 0;
 214         for (uint8_t i = 0x80; i != 0; i >>= 1)
 215         {
 216                 i2c_hw_sclLo(I2C_DEV(i2c));
 217                 i2c_hw_halfbitDelay(I2C_DEV(i2c));
 218                 i2c_hw_sclHi(I2C_DEV(i2c));
 219                 if (i2c_hw_sdaIn(I2C_DEV(i2c)))
 220                         data |= i;
 221                 else
 222                         data &= ~i;
 223
 224                 i2c_hw_halfbitDelay(I2C_DEV(i2c));
 225         }
 226         i2c_hw_sclLo(I2C_DEV(i2c));
 227
 228         /* Generate ACK/NACK */
 229         if (i2c->xfer_size > 1)
 230                 i2c_hw_sdaLo(I2C_DEV(i2c));
 231         else
 232                 i2c_hw_sdaHi(I2C_DEV(i2c));
 233
 234         i2c_hw_halfbitDelay(I2C_DEV(i2c));
 235         i2c_hw_sclHi(I2C_DEV(i2c));
 236         i2c_hw_halfbitDelay(I2C_DEV(i2c));
 237         i2c_hw_sclLo(I2C_DEV(i2c));
 238         i2c_hw_sdaHi(I2C_DEV(i2c));
 239
 240         /* Generate stop condition (if requested) */
 241         if ((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP))
 242                 i2c_bitbang_stop_1(i2c);
 243
 244         return data;
 245 }
 246
 247 static void i2c_bitbang_putc(struct I2c *i2c, uint8_t _data)
 248 {
 249         /* Add ACK bit */
 250         uint16_t data = (_data << 1) | 1;
 251
 252         for (uint16_t i = 0x100; i != 0; i >>= 1)
 253         {
 254                 i2c_hw_sclLo(I2C_DEV(i2c));
 255                 if (data & i)
 256                         i2c_hw_sdaHi(I2C_DEV(i2c));
 257                 else
 258                         i2c_hw_sdaLo(I2C_DEV(i2c));
 259                 i2c_hw_halfbitDelay(I2C_DEV(i2c));
 260
 261                 i2c_hw_sclHi(I2C_DEV(i2c));
 262                 i2c_hw_halfbitDelay(I2C_DEV(i2c));
 263         }
 264
 265         bool ack = !i2c_hw_sdaIn(I2C_DEV(i2c));
 266         i2c_hw_sclLo(I2C_DEV(i2c));
 267         i2c_hw_halfbitDelay(I2C_DEV(i2c));
 268
 269         if (!ack)
 270         {
 271                 LOG_ERR("NO ACK received\n");
 272                 i2c->errors |= I2C_NO_ACK;
 273         }
 274
 275         /* Generate stop condition (if requested) */
 276         if (((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP)) || i2c->errors)
 277                 i2c_bitbang_stop_1(i2c);
 278 }
 279
 280
 281 static void i2c_bitbang_start_2(struct I2c *i2c, uint16_t slave_addr)
 282 {
 283         if (i2c->flags & I2C_START_R)
 284                 slave_addr |= I2C_READBIT;
 285         else
 286                 slave_addr &= ~I2C_READBIT;
 287
 288         /*
 289          * Loop on the select write sequence: when the device is busy
 290          * writing previously sent data it will reply to the SLA_W
 291          * control byte with a NACK.  In this case, we must
 292          * keep trying until the deveice responds with an ACK.
 293          */
 294         ticks_t start = timer_clock();
 295         while (i2c_bitbang_start_1(i2c))
 296         {
 297                 i2c_bitbang_putc(i2c, slave_addr);
 298
 299                 if (!(i2c->errors & I2C_NO_ACK))
 300                         return;
 301                 else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
 302                 {
 303                         LOG_ERR("Timeout on I2C start\n");
 304                         i2c->errors |= I2C_START_TIMEOUT;
 305                         i2c_bitbang_stop_1(i2c);
 306                         return;
 307                 }
 308         }
 309
 310         LOG_ERR("START arbitration lost\n");
 311         i2c->errors |= I2C_ARB_LOST;
 312         i2c_bitbang_stop_1(i2c);
 313         return;
 314 }
 315
 316
 317 static const I2cVT i2c_bitbang_vt =
 318 {
 319         .start = i2c_bitbang_start_2,
 320         .getc = i2c_bitbang_getc,
 321         .putc = i2c_bitbang_putc,
 322         .write = i2c_genericWrite,
 323         .read = i2c_genericRead,
 324 };
 325
 326
 327 /**
 328  * Initialize i2c module.
 329  */
 330 void i2c_hw_bitbangInit(I2c *i2c, int dev)
 331 {
 332         MOD_CHECK(timer);
 333         i2c->hw = (struct I2cHardware *)(dev - I2C_BITBANG0);
 334         i2c->vt = &i2c_bitbang_vt;
 335
 336         i2c_hw_bitbang_init(I2C_DEV(i2c));
 337         i2c_hw_sdaHi(I2C_DEV(i2c));
 338         i2c_hw_sclHi(I2C_DEV(i2c));
 339 }
 340