File content as of revision 23:fb5f8e018461:

/**
 ******************************************************************************
 * @file    DevI2C.h
 * @author  AST / EST
 * @version V1.1.0
 * @date    21-January-2016
 * @brief   Header file for a special I2C class DevI2C which provides some
 *          helper function for on-board communication
 ******************************************************************************
 * @attention
 *
 * <h2><center>&copy; COPYRIGHT(c) 2016 STMicroelectronics</center></h2>
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *   1. Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the documentation
 *      and/or other materials provided with the distribution.
 *   3. Neither the name of STMicroelectronics nor the names of its contributors
 *      may be used to endorse or promote products derived from this software
 *      without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 ******************************************************************************
 */

/* Define to prevent from recursive inclusion --------------------------------*/
#ifndef __DEV_I2C_H
#define __DEV_I2C_H

/* Includes ------------------------------------------------------------------*/
#include "mbed.h"
#include "pinmap.h"

/* Classes -------------------------------------------------------------------*/
/** Helper class DevI2C providing functions for multi-register I2C communication
 *  common for a series of I2C devices
 */
class DevI2C : public I2C
{
public:
    /** Create a DevI2C Master interface, connected to the specified pins
     *
     *  @param sda I2C data line pin
     *  @param scl I2C clock line pin
     */
    DevI2C(PinName sda, PinName scl) : I2C(sda, scl) {}

    /** Create a DevI2C Master interface, connected to the specified pins and set their pin modes
     *
     *  @param sda I2C data line pin
     *  @param sda I2C data pin mode
     *  @param scl I2C clock line pin
     *  @param scl I2C clock pin mode
     *
     *  @note  this is a workaround to provide a constructor which currently
     *         is somehow missing in the I2C base class and it's underlying
     *         implementations. In some circumstances (e.g. while debugging)
     *         where long latencies between the initialization of the i2c
     *         interface in the I2C constructor and the setting of the pin
     *         modes in the beyond constructor might occur, the i2c
     *         communication might be compromised.
     */
    DevI2C(PinName sda, int mode_sda, PinName scl, int mode_scl) : I2C(sda, scl) {
        pin_mode(sda, (PinMode)mode_sda);
        pin_mode(scl, (PinMode)mode_scl);
    }

    /**
     * @brief  Writes a buffer towards the I2C peripheral device.
     * @param  pBuffer pointer to the byte-array data to send
     * @param  DeviceAddr specifies the peripheral device slave address.
     * @param  RegisterAddr specifies the internal address register
     *         where to start writing to (must be correctly masked).
     * @param  NumByteToWrite number of bytes to be written.
     * @retval 0 if ok,
     * @retval -1 if an I2C error has occured, or
     * @retval -2 on temporary buffer overflow (i.e. NumByteToWrite was too high)
     * @note   On some devices if NumByteToWrite is greater
     *         than one, the RegisterAddr must be masked correctly!
     */
    int i2c_write(uint8_t* pBuffer, uint8_t DeviceAddr, uint8_t RegisterAddr,
                  uint16_t NumByteToWrite) {
        int ret;
        uint8_t tmp[TEMP_BUF_SIZE];

        if(NumByteToWrite >= TEMP_BUF_SIZE) return -2;

        /* First, send device address. Then, send data and STOP condition */
        tmp[0] = RegisterAddr;
        memcpy(tmp+1, pBuffer, NumByteToWrite);

        ret = write(DeviceAddr, (const char*)tmp, NumByteToWrite+1, false);

        if(ret) return -1;
        return 0;
    }

    /**
     * @brief  Reads a buffer from the I2C peripheral device.
     * @param  pBuffer pointer to the byte-array to read data in to
     * @param  DaviceAddr specifies the peripheral device slave address.
     * @param  RegisterAddr specifies the internal address register
     *         where to start reading from (must be correctly masked).
     * @param  NumByteToRead number of bytes to be read.
     * @retval 0 if ok,
     * @retval -1 if an I2C error has occured
     * @note   On some devices if NumByteToWrite is greater
     *         than one, the RegisterAddr must be masked correctly!
     */
    int i2c_read(uint8_t* pBuffer, uint8_t DeviceAddr, uint8_t RegisterAddr,
                 uint16_t NumByteToRead) {
        int ret;

        /* Send device address, with no STOP condition */
        ret = write(DeviceAddr, (const char*)&RegisterAddr, 1, true);
        if(!ret) {
            /* Read data, with STOP condition  */
            ret = read(DeviceAddr, (char*)pBuffer, NumByteToRead, false);
        }

        if(ret) return -1;
        return 0;
    }

private:
    static const unsigned int TEMP_BUF_SIZE = 32;
};

#endif /* __DEV_I2C_H */