serial_debugger/hardware/_controller/src/SdFat/SpiDriver/SoftSPI.h

/**
 * Copyright (c) 2011-2018 Bill Greiman
 * This file is part of the SdFat library for SD memory cards.
 *
 * MIT License
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
/**
 * @file 
 * @brief  Software SPI.
 *
 * @defgroup softSPI Software SPI
 * @details  Software SPI Template Class.
 * @{
 */

#ifndef SoftSPI_h
#define SoftSPI_h
#include "DigitalPin.h"
//------------------------------------------------------------------------------
/** Nop for timing. */
#define nop asm volatile ("nop\n\t")
//------------------------------------------------------------------------------
/** Pin Mode for MISO is input.*/
#define MISO_MODE INPUT
/** Pullups disabled for MISO are disabled. */
#define MISO_LEVEL false
/** Pin Mode for MOSI is output.*/
#define MOSI_MODE  OUTPUT
/** Pin Mode for SCK is output. */
#define SCK_MODE  OUTPUT
//------------------------------------------------------------------------------
/**
 * @class SoftSPI
 * @brief Fast software SPI.
 */
template<uint8_t MisoPin, uint8_t MosiPin, uint8_t SckPin, uint8_t Mode = 0>
class SoftSPI {
 public:
  //----------------------------------------------------------------------------
  /** Initialize SoftSPI pins. */
  void begin() {
    fastPinConfig(MisoPin, MISO_MODE, MISO_LEVEL);
    fastPinConfig(MosiPin, MOSI_MODE, !MODE_CPHA(Mode));
    fastPinConfig(SckPin, SCK_MODE, MODE_CPOL(Mode));
  }
  //----------------------------------------------------------------------------
  /** Soft SPI receive byte.
   * @return Data byte received.
   */
  inline __attribute__((always_inline))
  uint8_t receive() {
    uint8_t data = 0;
    receiveBit(7, &data);
    receiveBit(6, &data);
    receiveBit(5, &data);
    receiveBit(4, &data);
    receiveBit(3, &data);
    receiveBit(2, &data);
    receiveBit(1, &data);
    receiveBit(0, &data);
    return data;
  }
  //----------------------------------------------------------------------------
  /** Soft SPI send byte.
   * @param[in] data Data byte to send.
   */
  inline __attribute__((always_inline))
  void send(uint8_t data) {
    sendBit(7, data);
    sendBit(6, data);
    sendBit(5, data);
    sendBit(4, data);
    sendBit(3, data);
    sendBit(2, data);
    sendBit(1, data);
    sendBit(0, data);
  }
  //----------------------------------------------------------------------------
  /** Soft SPI transfer byte.
   * @param[in] txData Data byte to send.
   * @return Data byte received.
   */
  inline __attribute__((always_inline))
  uint8_t transfer(uint8_t txData) {
    uint8_t rxData = 0;
    transferBit(7, &rxData, txData);
    transferBit(6, &rxData, txData);
    transferBit(5, &rxData, txData);
    transferBit(4, &rxData, txData);
    transferBit(3, &rxData, txData);
    transferBit(2, &rxData, txData);
    transferBit(1, &rxData, txData);
    transferBit(0, &rxData, txData);
    return rxData;
  }

 private:
  //----------------------------------------------------------------------------
  inline __attribute__((always_inline))
  bool MODE_CPHA(uint8_t mode) {return (mode & 1) != 0;}
  inline __attribute__((always_inline))
  bool MODE_CPOL(uint8_t mode) {return (mode & 2) != 0;}
  inline __attribute__((always_inline))
  void receiveBit(uint8_t bit, uint8_t* data) {
    if (MODE_CPHA(Mode)) {
      fastDigitalWrite(SckPin, !MODE_CPOL(Mode));
    }
    nop;
    nop;
    fastDigitalWrite(SckPin,
      MODE_CPHA(Mode) ? MODE_CPOL(Mode) : !MODE_CPOL(Mode));
    if (fastDigitalRead(MisoPin)) *data |= 1 << bit;
    if (!MODE_CPHA(Mode)) {
      fastDigitalWrite(SckPin, MODE_CPOL(Mode));
    }
  }
  //----------------------------------------------------------------------------
  inline __attribute__((always_inline))
  void sendBit(uint8_t bit, uint8_t data) {
    if (MODE_CPHA(Mode)) {
      fastDigitalWrite(SckPin, !MODE_CPOL(Mode));
    }
    fastDigitalWrite(MosiPin, data & (1 << bit));
    fastDigitalWrite(SckPin,
      MODE_CPHA(Mode) ? MODE_CPOL(Mode) : !MODE_CPOL(Mode));
    nop;
    nop;
    if (!MODE_CPHA(Mode)) {
      fastDigitalWrite(SckPin, MODE_CPOL(Mode));
    }
  }
  //----------------------------------------------------------------------------
  inline __attribute__((always_inline))
  void transferBit(uint8_t bit, uint8_t* rxData, uint8_t txData) {
    if (MODE_CPHA(Mode)) {
      fastDigitalWrite(SckPin, !MODE_CPOL(Mode));
    }
    fastDigitalWrite(MosiPin, txData & (1 << bit));
    fastDigitalWrite(SckPin,
      MODE_CPHA(Mode) ? MODE_CPOL(Mode) : !MODE_CPOL(Mode));
    if (fastDigitalRead(MisoPin)) *rxData |= 1 << bit;
    if (!MODE_CPHA(Mode)) {
      fastDigitalWrite(SckPin, MODE_CPOL(Mode));
    }
  }
  //----------------------------------------------------------------------------
};
#endif  // SoftSPI_h
/** @} */