RIOT/drivers/include/periph/i2c.h

/*
 * Copyright (C) 2014-2015 Freie Universität Berlin
 *
 * 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.
 */
/**
 * @defgroup    drivers_periph_i2c I2C
 * @ingroup     drivers_periph
 * @brief       Low-level I2C peripheral driver
 *
 * This is a simple I2C interface to allow platform independent access to a
 * MCU's I2C bus and peripherals. This interface is intentionally designed as
 * simple as possible, to allow for easy implementation and maximal portability.
 *
 * @note        The current version of this interface only supports the
 *              7-bit addressing mode.
 *
 * @note        This interface is due for remodeling, hence API changes are to
 *              be expected for upcoming releases.
 *
 * ## A note on pull-up resistors for SDA/SCL
 *
 * The I2C signal lines SDA/SCL need external pull-up resistors which connect
 * the lines to the positive voltage supply VCC. The I2C driver implementation
 * should enable the pin's internal pull-up resistors. There are however some
 * use cases for which the internal pull resistors are not strong enough and the
 * I2C bus will show faulty behavior. This can for example happen when
 * connecting a logic analyzer which will raise the capacitance of the bus. In
 * this case you should make sure you connect external pull-up resistors to both
 * I2C bus lines.
 *
 * The minimum and maximum resistances are computed by:
 * \f{eqnarray*}{
 * R_{min} &=& \frac{V_{DD} - V_{OL(max)}} {I_{OL}}\\
 * R_{max} &=& \frac{t_r} {(0.8473 \cdot C_b)}
 * \f}<br>
 * where:<br>
 * \f$ V_{DD} =\f$ Supply voltage,
 * \f$ V_{OL(max)} =\f$ Low level voltage,
 * \f$ I_{OL} =\f$ Low level output current,
 * \f$ t_r =\f$ Signal rise time,
 * \f$ C_b =\f$ Bus capacitance <br>
 * <br>The pull-up resistors depend on the bus speed.
 * Some typical values are:<br>
 * Normal mode:       10k&Omega;<br>
 * Fast mode:          2k&Omega;<br>
 * Fast plus mode:     2k&Omega;
 *
 * For more details refer to section 7.1 in:<br>
 * http://www.nxp.com/documents/user_manual/UM10204.pdf
 *
 * @{
 * @file
 * @brief       Low-level I2C peripheral driver interface definition
 *
 * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
 * @author      Thomas Eichinger <thomas.eichinger@fu-berlin.de>
 */
#ifndef PERIPH_I2C_H
#define PERIPH_I2C_H
#include <stdint.h>
#include <limits.h>
#include "periph_cpu.h"
/**
 * @todo    Remove dev_enums.h include once all platforms are ported to the
 *          updated periph interface
 */
#include "periph/dev_enums.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
 * @brief   Flag signaling a write operation on the bus
 */
#define I2C_FLAG_WRITE      0
/**
 * @brief   Flag signaling a read operation on the bus
 */
#define I2C_FLAG_READ       1
/**
 * @brief   Default I2C device access macro
 */
#ifndef I2C_DEV
#define I2C_DEV(x)          (x)
#endif
/**
 * @brief   Default I2C undefined value
 */
#ifndef I2C_UNDEF
#define I2C_UNDEF           (UINT_MAX)
#endif
/**
 * @brief   Default i2c_t type definition
 */
#ifndef HAVE_I2C_T
typedef unsigned int i2c_t;
#endif
/**
 * @brief   Default mapping of I2C bus speed values
 */
#ifndef HAVE_I2C_SPEED_T
typedef enum {
    I2C_SPEED_LOW = 0,      /**< low speed mode:    ~10kbit/s */
    I2C_SPEED_NORMAL,       /**< normal mode:       ~100kbit/s */
    I2C_SPEED_FAST,         /**< fast mode:         ~400kbit/sj */
    I2C_SPEED_FAST_PLUS,    /**< fast plus mode:    ~1Mbit/s */
    I2C_SPEED_HIGH,         /**< high speed mode:   ~3.4Mbit/s */
} i2c_speed_t;
#endif
/**
 * @brief   Initialize an I2C device to run as bus master
 *
 * @param[in] dev           the device to initialize
 * @param[in] speed         the selected bus speed
 *
 * @return                  0 on successful initialization
 * @return                  -1 on undefined device given
 * @return                  -2 on unsupported speed value
 */
int i2c_init_master(i2c_t dev, i2c_speed_t speed);
/**
 * @brief   Get mutually exclusive access to the given I2C bus
 *
 * In case the I2C device is busy, this function will block until the bus is
 * free again.
 *
 * @param[in] dev       I2C device to access
 *
 * @return              0 on success
 * @return              -1 on error
 */
int i2c_acquire(i2c_t dev);
/**
 * @brief   Release the given I2C device to be used by others
 *
 * @param[in] dev       I2C device to release
 *
 * @return              0 on success
 * @return              -1 on error
 */
int i2c_release(i2c_t dev);
/**
 * @brief   Read one byte from an I2C device with the given address
 *
 * @param[in]  dev          I2C peripheral device
 * @param[in]  address      bus address of the target device
 * @param[out] data         the result that was read
 *
 * @return                  the number of bytes that were read
 * @return                  -1 on undefined device given
 * @return                  -2 on invalid address
 */
int i2c_read_byte(i2c_t dev, uint8_t address, void *data);
/**
 * @brief   Read multiple bytes from an I2C device with the given address
 *
 * @param[in]  dev          I2C peripheral device
 * @param[in]  address      bus address of the target device
 * @param[out] data         array holding the received bytes
 * @param[in]  length       the number of bytes to read into `data`
 *
 * @return                  the number of bytes that were read
 * @return                  -1 on undefined device given
 */
int i2c_read_bytes(i2c_t dev, uint8_t address, void *data, int length);
/**
 * @brief   Read one byte from a register at the I2C slave with the given
 *          address
 *
 * @param[in]  dev          I2C peripheral device
 * @param[in]  address      bus address of the target device
 * @param[in]  reg          the register address on the targeted I2C device
 * @param[out] data         the result that was read
 *
 * @return                  the number of bytes that were read
 * @return                  -1 on undefined device given
 */
int i2c_read_reg(i2c_t dev, uint8_t address, uint8_t reg, void *data);
/**
 * @brief   Read multiple bytes from a register at the I2C slave with the given
 *          address
 *
 * @param[in]  dev          I2C peripheral device
 * @param[in]  address      bus address of the target device
 * @param[in]  reg          the register address on the targeted I2C device
 * @param[out] data         array holding the received bytes
 * @param[in]  length       the number of bytes to read into `data`
 *
 * @return                  the number of bytes that were read
 * @return                  -1 on undefined device given
 */
int i2c_read_regs(i2c_t dev, uint8_t address, uint8_t reg,
                  void *data, int length);
/**
 * @brief   Write one byte to an I2C device with the given address
 *
 * @param[in] dev           I2C peripheral device
 * @param[in] address       bus address of the target device
 * @param[in] data          byte to write to the device
 *
 * @return                  the number of bytes that were written
 * @return                  -1 on undefined device given
 */
int i2c_write_byte(i2c_t dev, uint8_t address, uint8_t data);
/**
 * @brief   Write multiple bytes to an I2C device with the given address
 *
 * @param[in] dev           I2C peripheral device
 * @param[in] address       bus address of the target device
 * @param[in] data          array with bytes to write to the target device
 * @param[in] length        number of bytes to write to the target device
 *
 * @return                  the number of bytes that were written
 * @return                  -1 on undefined device given
 */
int i2c_write_bytes(i2c_t dev, uint8_t address, const void *data, int length);
/**
 * @brief   Write one byte to a register at the I2C slave with the given address
 *
 * @param[in] dev           I2C peripheral device
 * @param[in] address       bus address of the target device
 * @param[in] reg           the register address on the targeted I2C device
 * @param[in] data          byte to write to the device
 *
 * @return                  the number of bytes that were written
 * @return                  -1 on undefined device given
 */
int i2c_write_reg(i2c_t dev, uint8_t address, uint8_t reg, uint8_t data);
/**
 * @brief   Write multiple bytes to a register at the I2C slave with the given
 *          address
 *
 * @param[in] dev           I2C peripheral device
 * @param[in] address       bus address of the target device
 * @param[in] reg           the register address on the targeted I2C device
 * @param[in] data          array with bytes to write to the target device
 * @param[in] length        number of bytes to write to the target device
 *
 * @return                  the number of bytes that were written
 * @return                  -1 on undefined device given
 */
int i2c_write_regs(i2c_t dev, uint8_t address, uint8_t reg,
                   const void *data, int length);
/**
 * @brief   Power on the given I2C peripheral
 *
 * @param[in] dev           the I2C device to power on
 */
void i2c_poweron(i2c_t dev);
/**
 * @brief   Power off the given I2C peripheral
 *
 * @param[in] dev           the I2C device to power off
 */
void i2c_poweroff(i2c_t dev);
#ifdef __cplusplus
}
#endif
#endif /* PERIPH_I2C_H */
/** @} */