125 lines
1.9 KiB
C++
125 lines
1.9 KiB
C++
#include "_Spi.h"
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SpiDevice::SpiDevice() {
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/*
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*/
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}
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void SpiDevice::begin() {
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/*
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Use the default chip select pin as specified by
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the SS define in the header.
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*/
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begin(SS);
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}
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void SpiDevice::begin(byte selectPin) {
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/*
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*/
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_selectPin = selectPin;
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_initPins();
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_initSpi();
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}
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void SpiDevice::_initPins() {
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/*
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Initialise the pins used for SPI communication.
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*/
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pinMode(MOSI, OUTPUT);
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pinMode(MISO, INPUT);
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pinMode(SCK, OUTPUT);
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pinMode(_selectPin, OUTPUT);
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deselect();
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}
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void SpiDevice::_initSpi() {
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/*
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Initialise SPI system.
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*/
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// From Table 18-5 in ATmega 48/88/168 datasheet:
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//
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// SPI2X | SPR1 | SPR0 | SCK Frequency
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// 1 | 0 | 0 | f_osc/2
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//
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// Where f_osc is the Oscillator Clock frequency
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//
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// This is the highest SPI clock frequency supported.
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SPCR = (1<<SPE)|(1<<MSTR)|(0<<SPR1)|(0<<SPR0);
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SPSR = SPSR | (1 << SPI2X);
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#if 0
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// This approach is not specified in the datasheet so I'm trying without.
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char clr = 0;
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clr=SPSR;
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clr=SPDR;
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delay(10);
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#endif
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}
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void SpiDevice::deselect() {
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/*
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Deselect the SPI device.
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*/
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digitalWrite(_selectPin, HIGH);
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}
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void SpiDevice::select() {
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/*
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Select the SPI device.
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*/
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digitalWrite(_selectPin, LOW);
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}
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byte SpiDevice::transfer(volatile byte data) {
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/*
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Transfer byte to SPI device and return
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the byte retrieved.
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*/
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SPDR = data; // Start the transmission
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while (!(SPSR & (1<<SPIF))) {
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// Wait for the end of the transmission
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};
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return SPDR; // Return the received byte
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}
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void SpiDevice::transfer_bulk(const uint8_t* srcptr, unsigned long int length) {
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/*
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Transfer an array of bytes to the SPI device.
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Discards all returned bytes.
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*/
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for(unsigned long int offset = 0; offset < length; offset++) {
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transfer(srcptr[offset]);
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}
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}
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