44 lines
1.1 KiB
C
44 lines
1.1 KiB
C
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/*
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spi lib 0x01
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copyright (c) Davide Gironi, 2012
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Released under GPLv3.
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Please refer to LICENSE file for licensing information.
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*/
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#include "spi.h"
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#include <avr/io.h>
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#include <avr/interrupt.h>
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/*
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* spi initialize
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*/
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void spi_init() {
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SPI_DDR &= ~((1<<SPI_MOSI) | (1<<SPI_MISO) | (1<<SPI_SS) | (1<<SPI_SCK)); //input
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SPI_DDR |= ((1<<SPI_MOSI) | (1<<SPI_SS) | (1<<SPI_SCK)); //output
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SPCR = ((1<<SPE)| // SPI Enable
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(0<<SPIE)| // SPI Interupt Enable
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(0<<DORD)| // Data Order (0:MSB first / 1:LSB first)
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(1<<MSTR)| // Master/Slave select
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(0<<SPR1)|(1<<SPR0)| // SPI Clock Rate
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(0<<CPOL)| // Clock Polarity (0:SCK low / 1:SCK hi when idle)
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(0<<CPHA)); // Clock Phase (0:leading / 1:trailing edge sampling)
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SPSR = (1<<SPI2X); // Double SPI Speed Bit
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}
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/*
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* spi write one byte and read it back
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*/
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uint8_t spi_writereadbyte(uint8_t data) {
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SPDR = data;
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while((SPSR & (1<<SPIF)) == 0);
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return SPDR;
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}
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