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RIOT/cpu/stm32l0/periph/i2c.c 11.8 KB
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  /*
   * Copyright (C) 2017 we-sens.com
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     cpu_stm32l0
   * @ingroup     drivers_periph_i2c
   * @{
   *
   * @file
   * @brief       Low-level I2C driver implementation
   *
   * @note This implementation only implements the 7-bit addressing polling mode
   * (for now interrupt mode is not available)
   *
   * @author      Aurélien Fillau <aurelien.fillau@we-sens.com>
   *
   * @}
   */
  
  #include <stdint.h>
  
  #include "cpu.h"
  #include "mutex.h"
  #include "periph/i2c.h"
  #include "periph/gpio.h"
  #include "periph_conf.h"
  
  #define ENABLE_DEBUG    (0)
  #include "debug.h"
  
  /* guard file in case no I2C device is defined */
  #if I2C_NUMOF
  
  /* static function definitions */
  static void _i2c_init(I2C_TypeDef *i2c, uint32_t presc, uint32_t scll,
                        uint32_t sclh, uint32_t sdadel, uint32_t scldel,
                        uint32_t timing);
  static void _start(I2C_TypeDef *dev, uint8_t address, uint8_t length, uint8_t rw_flag);
  static inline void _read(I2C_TypeDef *dev, uint8_t *data, int length);
  static inline void _write(I2C_TypeDef *i2c, const uint8_t *data, int length);
  static inline void _stop(I2C_TypeDef *i2c);
  
  /**
   * @brief Array holding one pre-initialized mutex for each I2C device
   */
  static mutex_t locks[] =  {
  #if I2C_0_EN
      [I2C_0] = MUTEX_INIT,
  #endif
  #if I2C_1_EN
      [I2C_1] = MUTEX_INIT,
  #endif
  #if I2C_2_EN
      [I2C_2] = MUTEX_INIT,
  #endif
  #if I2C_3_EN
      [I2C_3] = MUTEX_INIT
  #endif
  };
  
  int i2c_init_master(i2c_t dev, i2c_speed_t speed)
  {
      I2C_TypeDef *i2c;
      gpio_t scl_pin;
      gpio_t sda_pin;
      gpio_af_t scl_af;
      gpio_af_t sda_af;
      uint32_t presc, scll, sclh, sdadel, scldel, timing;
  
      /*
       * Speed configuration:
       * Example values can be found in the STM32L0xx Reference manual RM0367
       * with f_I2CCLK = 16MHz
       * t_SCLL: SCL low level counter
       * t_SCLH: SCL high level counter
       * t_SDADEL: Delay before sending SDA output
       * t_SCLDEL: SCL low level during setup-time
       */
      switch (speed) {
          case I2C_SPEED_NORMAL:
              presc = 1;
              scll = 0x56;  /* t_SCLL   = 5.0us */
              sclh = 0x3E;  /* t_SCLH   = 4.0us */
              sdadel = 0x1; /* t_SDADEL = 500ns */
              scldel = 0xA; /* t_SCLDEL = 1250ns */
              break;
  
          case I2C_SPEED_FAST:
              presc = 0;
              scll = 0x2E;  /* t_SCLL   = 1250ns */
              sclh = 0x11;  /* t_SCLH   = 500ns */
              sdadel = 0x1; /* t_SDADEL = 125ns */
              scldel = 0xB; /* t_SCLDEL = 500ns */
              break;
  
          case I2C_SPEED_FAST_PLUS:
              presc = 0;
              scll = 0x6;   /* t_SCLL   = 875ns */
              sclh = 0x3;   /* t_SCLH   = 500ns */
              sdadel = 0x0; /* t_SDADEL = 0ns */
              scldel = 0x1; /* t_SCLDEL = 250ns */
              break;
  
          default:
              return -2;
      }
  
      /* prepare the timing register value */
      timing = ((presc << 28) | (scldel << 20) | (sdadel << 16) | (sclh << 8) | scll);
  
      /* read static device configuration */
      switch (dev) {
  #if I2C_0_EN
          case I2C_0:
              i2c = I2C_0_DEV;
              scl_pin = GPIO_PIN(I2C_0_SCL_PORT, I2C_0_SCL_PIN);     /* scl pin number */
              sda_pin = GPIO_PIN(I2C_0_SDA_PORT, I2C_0_SDA_PIN);     /* sda pin number */
              scl_af = I2C_0_SCL_AF;
              sda_af = I2C_0_SDA_AF;
              I2C_0_CLKEN();
              I2C_0_SCL_CLKEN();
              I2C_0_SDA_CLKEN();
              break;
  #endif
  #if I2C_1_EN
          case I2C_1:
              i2c = I2C_1_DEV;
              scl_pin = GPIO_PIN(I2C_1_SCL_PORT, I2C_1_SCL_PIN);     /* scl pin number */
              sda_pin = GPIO_PIN(I2C_1_SDA_PORT, I2C_1_SDA_PIN);     /* sda pin number */
              scl_af = I2C_1_SCL_AF;
              sda_af = I2C_1_SDA_AF;
              I2C_1_CLKEN();
              I2C_1_SCL_CLKEN();
              I2C_1_SDA_CLKEN();
              break;
  #endif
  #if I2C_2_EN
          case I2C_2:
              i2c = I2C_2_DEV;
              scl_pin = GPIO_PIN(I2C_2_SCL_PORT, I2C_2_SCL_PIN);     /* scl pin number */
              sda_pin = GPIO_PIN(I2C_2_SDA_PORT, I2C_2_SDA_PIN);     /* sda pin number */
              scl_af = I2C_2_SCL_AF;
              sda_af = I2C_2_SDA_AF;
              I2C_2_CLKEN();
              I2C_2_SCL_CLKEN();
              I2C_2_SDA_CLKEN();
              break;
  #endif
  
          default:
              return -1;
      }
  
      /* configure pins */
      gpio_init(scl_pin, GPIO_OD_PU);
      gpio_init_af(scl_pin, scl_af);
      gpio_init(sda_pin, GPIO_OD_PU);
      gpio_init_af(sda_pin, sda_af);
  
      /* configure device */
      _i2c_init(i2c, presc, scll, sclh, sdadel, scldel, timing);
  
      return 0;
  }
  
  static void _i2c_init(I2C_TypeDef *i2c, uint32_t presc, uint32_t scll,
                        uint32_t sclh, uint32_t sdadel, uint32_t scldel,
                        uint32_t timing)
  {
      /* disable device */
      i2c->CR1 &= ~(I2C_CR1_PE);
  
      /* configure analog noise filter */
      i2c->CR1 |= I2C_CR1_ANFOFF;
  
      /* configure digital noise filter */
      i2c->CR1 |= I2C_CR1_DNF;
  
      /* set timing registers */
      i2c->TIMINGR = timing;
  
      /* configure clock stretching */
      i2c->CR1 &= ~(I2C_CR1_NOSTRETCH);
  
      /* enable device */
      i2c->CR1 |= I2C_CR1_PE;
  }
  
  int i2c_acquire(i2c_t dev)
  {
      if (dev >= I2C_NUMOF) {
          return -1;
      }
      mutex_lock(&locks[dev]);
      return 0;
  }
  
  int i2c_release(i2c_t dev)
  {
      if (dev >= I2C_NUMOF) {
          return -1;
      }
      mutex_unlock(&locks[dev]);
      return 0;
  }
  
  int i2c_read_byte(i2c_t dev, uint8_t address, void *data)
  {
      return i2c_read_bytes(dev, address, data, 1);
  }
  
  int i2c_read_bytes(i2c_t dev, uint8_t address, void *data, int length)
  {
      I2C_TypeDef *i2c;
  
      switch (dev) {
  #if I2C_0_EN
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  #if I2C_1_EN
          case I2C_1:
              i2c = I2C_1_DEV;
              break;
  #endif
  #if I2C_2_EN
          case I2C_2:
              i2c = I2C_2_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      /* start reception and send slave address */
      _start(i2c, address, length, I2C_FLAG_READ);
  
      /* read the data bytes */
      _read(i2c, data, length);
  
      /* end transmission */
      _stop(i2c);
  
      return length;
  }
  
  int i2c_read_reg(i2c_t dev, uint8_t address, uint8_t reg, void *data)
  {
      return i2c_read_regs(dev, address, reg, data, 1);
  }
  
  int i2c_read_regs(i2c_t dev, uint8_t address, uint8_t reg, void *data, int length)
  {
      I2C_TypeDef *i2c;
  
      switch (dev) {
  #if I2C_0_EN
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  #if I2C_1_EN
          case I2C_1:
              i2c = I2C_1_DEV;
              break;
  #endif
  #if I2C_2_EN
          case I2C_2:
              i2c = I2C_2_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      /* Check to see if the bus is busy */
      while((i2c->ISR & I2C_ISR_BUSY) == I2C_ISR_BUSY) {}
  
      /* send start sequence and slave address */
      _start(i2c, address, 1, I2C_FLAG_WRITE);
  
      /* wait for ack */
      DEBUG("Waiting for ACK\n");
      while (!(i2c->ISR & I2C_ISR_TXIS)) {}
  
      DEBUG("Write register to read\n");
      i2c->TXDR = reg;
  
      /* send repeated start sequence, read registers and end transmission */
      DEBUG("ACK received, send repeated start sequence\n");
      return i2c_read_bytes(dev, address, data, length);
  }
  
  int i2c_write_byte(i2c_t dev, uint8_t address, uint8_t data)
  {
      return i2c_write_bytes(dev, address, &data, 1);
  }
  
  int i2c_write_bytes(i2c_t dev, uint8_t address, const void *data, int length)
  {
      I2C_TypeDef *i2c;
  
      switch (dev) {
  #if I2C_0_EN
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  #if I2C_1_EN
          case I2C_1:
              i2c = I2C_1_DEV;
              break;
  #endif
  #if I2C_2_EN
          case I2C_2:
              i2c = I2C_2_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      /* start transmission and send slave address */
      _start(i2c, address, length, I2C_FLAG_WRITE);
  
      /* send out data bytes */
      _write(i2c, data, length);
  
      /* end transmission */
      _stop(i2c);
  
      return length;
  }
  
  int i2c_write_reg(i2c_t dev, uint8_t address, uint8_t reg, uint8_t data)
  {
      return i2c_write_regs(dev, address, reg, &data, 1);
  }
  
  int i2c_write_regs(i2c_t dev, uint8_t address, uint8_t reg, const void *data, int length)
  {
      I2C_TypeDef *i2c;
  
      switch (dev) {
  #if I2C_0_EN
          case I2C_0:
              i2c = I2C_0_DEV;
              break;
  #endif
  #if I2C_1_EN
          case I2C_1:
              i2c = I2C_1_DEV;
              break;
  #endif
  #if I2C_2_EN
          case I2C_2:
              i2c = I2C_2_DEV;
              break;
  #endif
  
          default:
              return -1;
      }
  
      /* Check to see if the bus is busy */
      while((i2c->ISR & I2C_ISR_BUSY) == I2C_ISR_BUSY);
  
      /* start transmission and send slave address */
      /* increase length because our data is register+data */
      _start(i2c, address, length+1, I2C_FLAG_WRITE);
  
      /* send register number */
      DEBUG("ACK received, write reg into DR\n");
      i2c->TXDR = reg;
  
      /* write out data bytes */
      _write(i2c, data, length);
  
      /* end transmission */
      _stop(i2c);
  
      return length;
  }
  
  void i2c_poweron(i2c_t dev)
  {
      switch (dev) {
  #if I2C_0_EN
          case I2C_0:
              I2C_0_CLKEN();
              break;
  #endif
  #if I2C_1_EN
          case I2C_1:
              I2C_1_CLKEN();
              break;
  #endif
  #if I2C_2_EN
          case I2C_2:
              I2C_2_CLKEN();
              break;
  #endif
      }
  }
  
  void i2c_poweroff(i2c_t dev)
  {
      switch (dev) {
  #if I2C_0_EN
          case I2C_0:
              while (I2C_0_DEV->ISR & I2C_ISR_BUSY) {}
  
              I2C_0_CLKDIS();
              break;
  #endif
  #if I2C_1_EN
          case I2C_1:
              while (I2C_1_DEV->ISR & I2C_ISR_BUSY) {}
  
              I2C_1_CLKDIS();
              break;
  #endif
  #if I2C_2_EN
          case I2C_2:
              while (I2C_2_DEV->ISR & I2C_ISR_BUSY) {}
  
              I2C_2_CLKDIS();
              break;
  #endif
      }
  }
  
  static void _start(I2C_TypeDef *dev, uint8_t address, uint8_t length, uint8_t rw_flag)
  {
      dev->CR2 = 0;
      /* set address mode to 7-bit */
      dev->CR2 &= ~(I2C_CR2_ADD10);
  
      /* set slave address */
      dev->CR2 &= ~(I2C_CR2_SADD);
      dev->CR2 |= (address << 1);
  
      /* set transfer direction */
      dev->CR2 &= ~(I2C_CR2_RD_WRN);
      dev->CR2 |= (rw_flag << I2C_CR2_RD_WRN_Pos);
  
      /* set number of bytes */
      dev->CR2 &= ~(I2C_CR2_NBYTES);
      dev->CR2 |= (length << I2C_CR2_NBYTES_Pos);
  
      /* configure autoend configuration */
      dev->CR2 &= ~(I2C_CR2_AUTOEND);
  
      /* generate start condition */
      DEBUG("Generate start condition\n");
      dev->CR2 |= I2C_CR2_START;
  
      /* Wait for the start followed by the address to be sent */
      while (!(dev->CR2 & I2C_CR2_START)) {}
  }
  
  static inline void _read(I2C_TypeDef *dev, uint8_t *data, int length)
  {
      for (int i = 0; i < length; i++) {
          /* wait for transfer to finish */
          DEBUG("Waiting for DR to be full\n");
          while (!(dev->ISR & I2C_ISR_RXNE)) {}
          DEBUG("DR is now full\n");
  
          /* read data from data register */
          data[i] = dev->RXDR;
          DEBUG("Read byte %i from DR\n", i);
      }
  }
  
  static inline void _write(I2C_TypeDef *dev, const uint8_t *data, int length)
  {
      for (int i = 0; i < length; i++) {
          /* wait for ack */
          DEBUG("Waiting for ACK\n");
          while (!(dev->ISR & I2C_ISR_TXIS)) {}
  
          /* write data to data register */
          DEBUG("Write byte %i to DR\n", i);
          dev->TXDR = data[i];
          DEBUG("Sending data\n");
      }
  }
  
  static inline void _stop(I2C_TypeDef *dev)
  {
      /* make sure transfer is complete */
      DEBUG("Wait for transfer to be complete\n");
      while (!(dev->ISR & I2C_ISR_TC)) {}
  
      /* send STOP condition */
      DEBUG("Generate stop condition\n");
      dev->CR2 |= I2C_CR2_STOP;
  }
  
  #endif /* I2C_NUMOF */