root / branches / encoders / code / projects / libdragonfly / spi.c @ 252
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/*
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* SPI MODULE
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*
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* ...work in progress
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*/
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/*
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PINS:
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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 */
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#define DOUBLE_SCK 1 |
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#define SPR0_BIT 1 |
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#define LSB 1 |
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#define MSB 0 |
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RING_BUFFER_NEW(spi_buffer, 64, char, spi_send_buff, spi_rec_buff); |
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char spi_status;
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int
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spi_init() |
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{ |
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RING_BUFFER_CLEAR(spi_send_buff); |
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RING_BUFFER_CLEAR(spi_rec_buff); |
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/* Set MOSI and SCK as output -- also SS for now...*/
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DDR_SPI = (1<<PB2)|(1<<PB1)|(1<<PB0); |
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SPCR = (1<<SPIE)|(1<<SPE)|(LSB<<DORD)|(1<<MSTR)| |
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(SPR1_BIT<<SPR1)|(SPR0_BIT<<SPR0); |
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SPSR = (1<<SPIF)|(DOUBLE_SCK<<SPI2X);
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} |
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void
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spi_send(char *data, size_t bytes)
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{ |
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if(bytes == 0) return -1; /* ...needed?*/ |
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cli(); |
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for(i = 1; i < bytes; i++) { |
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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_SENDING; |
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SPDR = *data; |
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} |
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char
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spi_receive(void)
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{ |
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spi_status = SENDING; |
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return SPDR;
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} |
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ISR(SIG_SPI) { |
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char c;
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switch(spi_status){
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case SENDING:
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if(!RING_BUFFER_EMPTY(spi_send_buff)) {
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RING_BUFFER_REMOVE(spi_send_buff, c); |
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SPDR = c; |
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} else {
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/* notify of sent? */
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spi_status = VOID; |
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} |
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break;
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case RECEIVING:
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spi_send_func(SPDR); |
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break;
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} |