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/* @file spi.c
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* @brief
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* SPI module
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* @bug broken
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*/
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#include <avr/interrupt.h> |
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#include "ring_buffer.h" |
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#include "spi.h" |
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#include <dragonfly_lib.h> |
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/*
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SS = PB0
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SCK = PB1
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MOSI = PB2
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MISO = PB3
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*/
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/* Controls clock freq. see Table 72 of specs*/
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#define DOUBLE_SCK 1 |
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#define SPR0_BIT 1 |
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#define SPR1_BIT 0 |
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#define LSB 1 |
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#define MSB 0 |
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RING_BUFFER_NEW(spi_buffer, 16, char, spi_send_buff, spi_rec_buff); |
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volatile char spi_status; |
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char spi_mode;
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static spi_fun_recv_t spi_recv_function;
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//static spi_fun_send_t spi_send_function;
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void spi_init(char mode, spi_fun_recv_t recv_func) { |
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usb_puts("spi_init: start\n");
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spi_mode = mode; |
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RING_BUFFER_CLEAR(spi_send_buff); |
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RING_BUFFER_CLEAR(spi_rec_buff); |
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spi_recv_function = recv_func; |
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//spi_send_function = send_func;
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/* Enables the SPI module
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* Enable Interrupt, Enable SPI Module, LSB First, Master Mode, Clock div = 64
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*/
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SPCR = 0x00;
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SPCR = _BV(SPIE) | _BV(SPE) | _BV(DORD) | _BV(MSTR)| _BV(SPR1) | _BV(SPR0); |
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SPSR = 0x00;
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SPSR = _BV(SPI2X); |
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spi_status = SPI_RECV; |
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/* Set SCLK, SS, MOSI as outputs. MISO as input */
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if(mode == MASTER) {
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DDRB |= MOSI | SCLK | SS; |
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DDRB &= ~MISO; |
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PORTB |= SS; //Keep SS High until transmit
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/* Set SCLK, SS, MOSI as inputs. MISO as output */
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} else {
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DDRB &= ~MOSI & ~SCLK & ~SS; |
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DDRB |= MISO; |
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} |
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//sei();
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usb_puts("spi_init: end\n");
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} |
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int spi_send(char *data, size_t bytes) { |
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int i;
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if(bytes == 0) |
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return -1; /* ...needed?*/ |
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//Prevent race condition on the buffer
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cli(); |
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for(i = 1; i < bytes; i++) { |
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// Fail if the buffer is full
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if(RING_BUFFER_FULL(spi_send_buff)) {
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sei(); |
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return -1; |
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} |
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RING_BUFFER_ADD(spi_send_buff, data[i]); |
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} |
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sei(); |
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spi_status |= SPI_SEND; |
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if (spi_mode == MASTER ){
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PORTB &= ~SS; //Select slave
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} |
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SPDR = *data; |
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if(spi_mode)
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usb_puts("MASTER");
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else
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usb_puts("SLAVE");
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usb_puts(": sending [");usb_putc(*data);usb_puts("]\n\r"); |
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//sei();
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return 1; |
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} |
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void spi_read_one(void) |
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{ |
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PORTB &= ~SS; |
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SPDR = 'x';
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} |
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ISR(SIG_SPI) { |
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char c;
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if(!RING_BUFFER_EMPTY(spi_send_buff)) {//cheap way to test if SPI_SEND |
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RING_BUFFER_REMOVE(spi_send_buff, c); |
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SPDR = c; |
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if(spi_mode)
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usb_puts("MASTER");
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else
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usb_puts("SLAVE");
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usb_puts(": sending [");usb_putc(c);usb_puts("]\n\r"); |
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} else if(spi_status & SPI_SEND) { |
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spi_status ^= SPI_SEND; |
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PORTB |= SS; //Sleep slave
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} |
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if(spi_status & SPI_RECV){
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spi_recv_function(SPDR); |
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if(spi_mode == MASTER)
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PORTB |= SS; |
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} |
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} |
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