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63 lines
1.3 KiB
63 lines
1.3 KiB
9 years ago
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#include <avr/io.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include "iopins.h"
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#include "spi.h"
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/** Init SPI (for SD card communication) */
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void spi_init_master(enum SPI_order order, enum SPI_cpol cpol, enum SPI_cpha cpha, enum SPI_clk_div clkdiv)
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{
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as_output(PIN_SS); // SS output - we control slave
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as_output(PIN_MOSI); // MOSI output - we talk to slave
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as_output(PIN_SCK); // SCK output - we're generating clock
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// MISO is configured automatically as input
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SPCR = 0;
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SPCR |= (1 << MSTR);
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SPCR |= (order << DORD);
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SPCR |= (cpol << CPOL);
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SPCR |= (cpha << CPHA);
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// speed
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SPCR |= (clkdiv & 0b11);
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SPSR = (bool)(clkdiv & 0b100); // write SPI2X flag
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// enable SPI
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SPCR |= (1 << SPE);
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}
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/** Init SPI (for SD card communication) */
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void spi_init_slave(enum SPI_order order, enum SPI_cpol cpol, enum SPI_cpha cpha)
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{
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as_output(PIN_MISO); // we're listening to master
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// MOSI, SS, SCK are configured automatically
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SPCR = 0;
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SPCR |= (order << DORD);
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SPCR |= (cpol << CPOL);
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SPCR |= (cpha << CPHA);
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// enable SPI
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SPCR |= (1 << SPE);
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}
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/** Write a byte to SPI. Returns received byte. */
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uint8_t spi_send(uint8_t byte)
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{
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SPDR = byte;
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while (bit_is_low(SPSR, SPIF));
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return SPDR;
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}
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/** Receive (as slave). Blocking. */
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uint8_t spi_receive(uint8_t reply)
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{
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SPDR = reply;
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while (bit_is_low(SPSR, SPIF));
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return SPDR;
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}
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