168 lines
5.6 KiB
C++
168 lines
5.6 KiB
C++
/**
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* Copyright (c) 2011-2018 Bill Greiman
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* This file is part of the SdFat library for SD memory cards.
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*
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* MIT License
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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/**
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* @file
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* @brief Software SPI.
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*
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* @defgroup softSPI Software SPI
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* @details Software SPI Template Class.
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* @{
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*/
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#ifndef SoftSPI_h
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#define SoftSPI_h
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#include "DigitalPin.h"
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//------------------------------------------------------------------------------
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/** Nop for timing. */
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#define nop asm volatile ("nop\n\t")
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//------------------------------------------------------------------------------
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/** Pin Mode for MISO is input.*/
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#define MISO_MODE INPUT
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/** Pullups disabled for MISO are disabled. */
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#define MISO_LEVEL false
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/** Pin Mode for MOSI is output.*/
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#define MOSI_MODE OUTPUT
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/** Pin Mode for SCK is output. */
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#define SCK_MODE OUTPUT
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//------------------------------------------------------------------------------
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/**
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* @class SoftSPI
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* @brief Fast software SPI.
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*/
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template<uint8_t MisoPin, uint8_t MosiPin, uint8_t SckPin, uint8_t Mode = 0>
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class SoftSPI {
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public:
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//----------------------------------------------------------------------------
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/** Initialize SoftSPI pins. */
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void begin() {
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fastPinConfig(MisoPin, MISO_MODE, MISO_LEVEL);
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fastPinConfig(MosiPin, MOSI_MODE, !MODE_CPHA(Mode));
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fastPinConfig(SckPin, SCK_MODE, MODE_CPOL(Mode));
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}
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//----------------------------------------------------------------------------
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/** Soft SPI receive byte.
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* @return Data byte received.
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*/
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inline __attribute__((always_inline))
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uint8_t receive() {
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uint8_t data = 0;
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receiveBit(7, &data);
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receiveBit(6, &data);
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receiveBit(5, &data);
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receiveBit(4, &data);
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receiveBit(3, &data);
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receiveBit(2, &data);
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receiveBit(1, &data);
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receiveBit(0, &data);
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return data;
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}
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//----------------------------------------------------------------------------
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/** Soft SPI send byte.
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* @param[in] data Data byte to send.
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*/
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inline __attribute__((always_inline))
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void send(uint8_t data) {
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sendBit(7, data);
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sendBit(6, data);
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sendBit(5, data);
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sendBit(4, data);
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sendBit(3, data);
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sendBit(2, data);
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sendBit(1, data);
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sendBit(0, data);
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}
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//----------------------------------------------------------------------------
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/** Soft SPI transfer byte.
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* @param[in] txData Data byte to send.
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* @return Data byte received.
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*/
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inline __attribute__((always_inline))
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uint8_t transfer(uint8_t txData) {
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uint8_t rxData = 0;
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transferBit(7, &rxData, txData);
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transferBit(6, &rxData, txData);
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transferBit(5, &rxData, txData);
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transferBit(4, &rxData, txData);
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transferBit(3, &rxData, txData);
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transferBit(2, &rxData, txData);
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transferBit(1, &rxData, txData);
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transferBit(0, &rxData, txData);
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return rxData;
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}
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private:
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//----------------------------------------------------------------------------
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inline __attribute__((always_inline))
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bool MODE_CPHA(uint8_t mode) {return (mode & 1) != 0;}
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inline __attribute__((always_inline))
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bool MODE_CPOL(uint8_t mode) {return (mode & 2) != 0;}
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inline __attribute__((always_inline))
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void receiveBit(uint8_t bit, uint8_t* data) {
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if (MODE_CPHA(Mode)) {
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fastDigitalWrite(SckPin, !MODE_CPOL(Mode));
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}
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nop;
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nop;
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fastDigitalWrite(SckPin,
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MODE_CPHA(Mode) ? MODE_CPOL(Mode) : !MODE_CPOL(Mode));
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if (fastDigitalRead(MisoPin)) *data |= 1 << bit;
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if (!MODE_CPHA(Mode)) {
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fastDigitalWrite(SckPin, MODE_CPOL(Mode));
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}
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}
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//----------------------------------------------------------------------------
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inline __attribute__((always_inline))
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void sendBit(uint8_t bit, uint8_t data) {
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if (MODE_CPHA(Mode)) {
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fastDigitalWrite(SckPin, !MODE_CPOL(Mode));
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}
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fastDigitalWrite(MosiPin, data & (1 << bit));
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fastDigitalWrite(SckPin,
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MODE_CPHA(Mode) ? MODE_CPOL(Mode) : !MODE_CPOL(Mode));
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nop;
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nop;
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if (!MODE_CPHA(Mode)) {
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fastDigitalWrite(SckPin, MODE_CPOL(Mode));
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}
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}
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//----------------------------------------------------------------------------
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inline __attribute__((always_inline))
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void transferBit(uint8_t bit, uint8_t* rxData, uint8_t txData) {
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if (MODE_CPHA(Mode)) {
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fastDigitalWrite(SckPin, !MODE_CPOL(Mode));
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}
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fastDigitalWrite(MosiPin, txData & (1 << bit));
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fastDigitalWrite(SckPin,
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MODE_CPHA(Mode) ? MODE_CPOL(Mode) : !MODE_CPOL(Mode));
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if (fastDigitalRead(MisoPin)) *rxData |= 1 << bit;
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if (!MODE_CPHA(Mode)) {
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fastDigitalWrite(SckPin, MODE_CPOL(Mode));
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}
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}
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//----------------------------------------------------------------------------
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};
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#endif // SoftSPI_h
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/** @} */
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