File content as of revision 15:923ab55e8d5d:

/**
 ******************************************************************************
 * @file    DevSPI.h
 * @author  AST / Software Platforms and Cloud
 * @version V1.0.1
 * @date    February 11th, 2016
 * @brief   Header file for a special SPI class DevSPI which provides some
 *          helper function for on-board communication.
 ******************************************************************************
 * @attention
 *
 * <h2><center>&copy; COPYRIGHT(c) 2014 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_SPI_H
#define __DEV_SPI_H

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

/* Classes -------------------------------------------------------------------*/
/** Helper class DevSPI providing functions for SPI communication common for a
 *  series of SPI devices.
 */
class DevSPI : public SPI
{
 public:
    /*
     * Create a DevSPI interface.
     * @param mosi pin name of the MOSI pin of the SPI device to be used for communication.
     * @param miso pin name of the MISO pin of the SPI device to be used for communication.
     * @param sclk pin name of the SCLK pin of the SPI device to be used for communication.
     */
    DevSPI(PinName mosi, PinName miso, PinName sclk) : SPI(mosi, miso, sclk)
    {
        /* Set default configuration. */
        setup(8, 3, 1E6);
    }

    /*
     * Setup the spi.
     * Typically:
     *  + 8 bit data;
     *  + high steady state clock;
     *  + second edge capture;
     *  + 1MHz clock rate.
     *
     * @param bits         Number of bits per SPI frame (4 - 16)
     * @param mode         Clock polarity and phase mode (0 - 3)
     * @param frequency_hz SCLK frequency in hz (default = 1MHz)
     *
     * @code
     * mode | POL PHA
     * -----+--------
     *   0  |  0   0
     *   1  |  0   1
     *   2  |  1   0
     *   3  |  1   1
     * @endcode
     */
    void setup(int bits, int mode = 0, int frequency_hz = 1E6)
    {
        /* Set given configuration. */
        format(bits, mode);
        frequency(frequency_hz);
    }

    /**
     * @brief      Writes a buffer to the SPI peripheral device.
     * @param[in]  pBuffer pointer to the buffer of data to send.
     * @param[in]  ssel GPIO of the SSEL pin of the SPI device to be used for communication.
     * @param[in]  NumBytesToWrite number of bytes to write.
     * @retval     0 if ok.
     * @note       When using the SPI in Interrupt-mode, remember to disable interrupts
     *             before calling this function and to enable them again after.
     */
    int spi_write(uint8_t* pBuffer, DigitalOut ssel, uint16_t NumBytesToWrite)
    {
        /* Select the chip. */
        ssel = 0;
        
        /* Write data. */
        if (_bits == 16) {
            uint16_t dataToWrite;
            for (int i = 0; i < NumBytesToWrite; i += 2) {
                dataToWrite = convertFrom8To16(pBuffer);
                write(dataToWrite);
                pBuffer += sizeof(uint16_t);
            }

        } else if(_bits == 8) {
            for (int i = 0; i < NumBytesToWrite; i++) {
                write(pBuffer[i]);
            }
        }

        /* Unselect the chip. */
        ssel = 1;

        return 0;
    }

    /**
     * @brief      Reads a buffer from the SPI peripheral device.
     * @param[out] pBuffer pointer to the buffer to read data into.
     * @param[in]  ssel GPIO of the SSEL pin of the SPI device to be used for communication.
     * @param[in]  NumBytesToRead number of bytes to read.
     * @retval     0 if ok.
     * @note       When using the SPI in Interrupt-mode, remember to disable interrupts
     *             before calling this function and to enable them again after.
     */
    int spi_read(uint8_t* pBuffer, DigitalOut ssel, uint16_t NumBytesToRead)
    {
        /* Select the chip. */
        ssel = 0;
        
        /* Read data. */
        if (_bits == 16) {
            uint16_t dataToRead;
            for (int i = 0; i < NumBytesToRead; i += 2) {
                dataToRead = write(0x00);
                convertFrom16To8(dataToRead, pBuffer);
                pBuffer += sizeof(uint16_t);
            }

        } else if(_bits == 8) {
            for (int i = 0; i < NumBytesToRead; i++) {
                pBuffer[i] = write(0x00);
            }
        }

        /* Unselect the chip. */
        ssel = 1;

        return 0;
    }

    /**
     * @brief      Reads and write a buffer from/to the SPI peripheral device at the same time.
     * @param[out] pBufferToRead pointer to the buffer to read data into.
     * @param[in]  pBufferToWrite pointer to the buffer of data to send.
     * @param[in]  ssel GPIO of the SSEL pin of the SPI device to be used for communication.
     * @param[in]  NumBytes number of bytes to read and write.
     * @retval     0 if ok.
     * @note       When using the SPI in Interrupt-mode, remember to disable interrupts
     *             before calling this function and to enable them again after.
     */
    int spi_read_write(uint8_t* pBufferToRead, uint8_t* pBufferToWrite, DigitalOut ssel, uint16_t NumBytes)
    {
        /* Select the chip. */
        ssel = 0;
        
        /* Read and write data at the same time. */
        if (_bits == 16) {
            uint16_t dataToRead;
            uint16_t dataToWrite;

            for (int i = 0; i < NumBytes; i += 2) {
                dataToWrite = convertFrom8To16(pBufferToWrite);
                
                dataToRead = write(dataToWrite);
                
                convertFrom16To8(dataToRead, pBufferToRead);
                
                pBufferToWrite += sizeof(uint16_t);
                pBufferToRead += sizeof(uint16_t);
            }

        } else if(_bits == 8) {
            for (int i = 0; i < NumBytes; i++) {
                pBufferToRead[i] = write(pBufferToWrite[i]);
            }
        }

        /* Unselect the chip. */
        ssel = 1;

        return 0;
    }

private:

    /**
     * @brief      Converts two uint8_t words into one of uint16_t
     * @param[in]  ptr pointer to the buffer of data to be converted.
     * @retval     16-bit data.
     */
    uint16_t convertFrom8To16(uint8_t *ptr)
    {
        uint16_t data16 = 0x0000;
        
        data16 = *ptr;
        data16 |= *(++ptr) << 8;
        
        return data16;
    }

    /**
     * @brief      Converts one uint16_t word into two uint8_t
     * @param[in]  ptr pointer to the buffer of uint8_t words.
     * @param[in]  16-bit data.
     * @retval     none.
     */
    void convertFrom16To8(uint16_t data16, uint8_t *ptr)
    {
        *(ptr) = data16 & 0x00FF;
        *(++ptr) = (data16 >> 8) & 0x00FF;
    }

};

#endif /* __DEV_SPI_H */