120 lines
3.8 KiB
C++
120 lines
3.8 KiB
C++
#ifndef SoftSPI_h
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#define SoftSPI_h
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#include <DigitalPin.h>
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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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/**
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* \class SoftSPI
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* \brief fast bit-bang 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 */
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void begin() {
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fastPinMode(MisoPin, false);
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fastPinMode(MosiPin, true);
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fastPinMode(SckPin, true);
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fastDigitalWrite(SckPin, MODE_CPOL(Mode));
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}
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//----------------------------------------------------------------------------
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/** Soft SPI receive byte
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* \return byte received
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*/
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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 byte to send
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*/
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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 byte to send
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* \return 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;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;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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