DevI2C.h

00001 /**
00002  ******************************************************************************
00003  * @file    DevI2C.h
00004  * @author  AST / EST
00005  * @version V1.1.0
00006  * @date    21-January-2016
00007  * @brief   Header file for a special I2C class DevI2C which provides some
00008  *          helper function for on-board communication
00009  ******************************************************************************
00010  * @attention
00011  *
00012  * <h2><center>&copy; COPYRIGHT(c) 2016 STMicroelectronics</center></h2>
00013  *
00014  * Redistribution and use in source and binary forms, with or without modification,
00015  * are permitted provided that the following conditions are met:
00016  *   1. Redistributions of source code must retain the above copyright notice,
00017  *      this list of conditions and the following disclaimer.
00018  *   2. Redistributions in binary form must reproduce the above copyright notice,
00019  *      this list of conditions and the following disclaimer in the documentation
00020  *      and/or other materials provided with the distribution.
00021  *   3. Neither the name of STMicroelectronics nor the names of its contributors
00022  *      may be used to endorse or promote products derived from this software
00023  *      without specific prior written permission.
00024  *
00025  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
00026  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00027  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
00028  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
00029  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00030  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
00031  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00032  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00033  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
00034  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00035  *
00036  ******************************************************************************
00037  */
00038 
00039 /* Define to prevent from recursive inclusion --------------------------------*/
00040 #ifndef __DEV_I2C_H
00041 #define __DEV_I2C_H
00042 
00043 /* Includes ------------------------------------------------------------------*/
00044 #include "mbed.h"
00045 #include "pinmap.h"
00046 
00047 /* Classes -------------------------------------------------------------------*/
00048 /** Helper class DevI2C providing functions for multi-register I2C communication
00049  *  common for a series of I2C devices
00050  */
00051 class DevI2C : public I2C
00052 {
00053 public:
00054     /** Create a DevI2C Master interface, connected to the specified pins
00055      *
00056      *  @param sda I2C data line pin
00057      *  @param scl I2C clock line pin
00058      */
00059     DevI2C(PinName sda, PinName scl) : I2C(sda, scl) {}
00060 
00061     /** Create a DevI2C Master interface, connected to the specified pins and set their pin modes
00062      *
00063      *  @param sda I2C data line pin
00064      *  @param sda I2C data pin mode
00065      *  @param scl I2C clock line pin
00066      *  @param scl I2C clock pin mode
00067      *
00068      *  @note  this is a workaround to provide a constructor which currently
00069      *         is somehow missing in the I2C base class and it's underlying
00070      *         implementations. In some circumstances (e.g. while debugging)
00071      *         where long latencies between the initialization of the i2c
00072      *         interface in the I2C constructor and the setting of the pin
00073      *         modes in the beyond constructor might occur, the i2c
00074      *         communication might be compromised.
00075      */
00076     DevI2C(PinName sda, int mode_sda, PinName scl, int mode_scl) : I2C(sda, scl) {
00077         pin_mode(sda, (PinMode)mode_sda);
00078         pin_mode(scl, (PinMode)mode_scl);
00079     }
00080 
00081     /**
00082      * @brief  Writes a buffer towards the I2C peripheral device.
00083      * @param  pBuffer pointer to the byte-array data to send
00084      * @param  DeviceAddr specifies the peripheral device slave address.
00085      * @param  RegisterAddr specifies the internal address register
00086      *         where to start writing to (must be correctly masked).
00087      * @param  NumByteToWrite number of bytes to be written.
00088      * @retval 0 if ok,
00089      * @retval -1 if an I2C error has occured, or
00090      * @retval -2 on temporary buffer overflow (i.e. NumByteToWrite was too high)
00091      * @note   On some devices if NumByteToWrite is greater
00092      *         than one, the RegisterAddr must be masked correctly!
00093      */
00094     int i2c_write(uint8_t* pBuffer, uint8_t DeviceAddr, uint8_t RegisterAddr,
00095                   uint16_t NumByteToWrite) {
00096         int ret;
00097         uint8_t tmp[TEMP_BUF_SIZE];
00098 
00099         if(NumByteToWrite >= TEMP_BUF_SIZE) return -2;
00100 
00101         /* First, send device address. Then, send data and STOP condition */
00102         tmp[0] = RegisterAddr;
00103         memcpy(tmp+1, pBuffer, NumByteToWrite);
00104 
00105         ret = write(DeviceAddr, (const char*)tmp, NumByteToWrite+1, false);
00106 
00107         if(ret) return -1;
00108         return 0;
00109     }
00110 
00111     /**
00112      * @brief  Reads a buffer from the I2C peripheral device.
00113      * @param  pBuffer pointer to the byte-array to read data in to
00114      * @param  DaviceAddr specifies the peripheral device slave address.
00115      * @param  RegisterAddr specifies the internal address register
00116      *         where to start reading from (must be correctly masked).
00117      * @param  NumByteToRead number of bytes to be read.
00118      * @retval 0 if ok,
00119      * @retval -1 if an I2C error has occured
00120      * @note   On some devices if NumByteToWrite is greater
00121      *         than one, the RegisterAddr must be masked correctly!
00122      */
00123     int i2c_read(uint8_t* pBuffer, uint8_t DeviceAddr, uint8_t RegisterAddr,
00124                  uint16_t NumByteToRead) {
00125         int ret;
00126 
00127         /* Send device address, with no STOP condition */
00128         ret = write(DeviceAddr, (const char*)&RegisterAddr, 1, true);
00129         if(!ret) {
00130             /* Read data, with STOP condition  */
00131             ret = read(DeviceAddr, (char*)pBuffer, NumByteToRead, false);
00132         }
00133 
00134         if(ret) return -1;
00135         return 0;
00136     }
00137 
00138 private:
00139     static const unsigned int TEMP_BUF_SIZE = 32;
00140 };
00141 
00142 #endif /* __DEV_I2C_H */