root / trunk / code / projects / libdragonfly / spi.c @ 1461
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| 1 | 868 | justin | /**
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| 2 | * @file spi.c
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| 3 | * @brief Basic SPI module to handle encoders
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| 4 | * @author Colony Project, CMU Robotics Club
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| 5 | * Need to move spi.h include into dragonfly_lib.h when stable
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| 6 | **/
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| 7 | |||
| 8 | #include <avr/interrupt.h> |
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| 9 | #include "spi.h" |
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| 10 | |||
| 11 | 1461 | bneuman | unsigned char spi_initd=0; |
| 12 | 868 | justin | |
| 13 | static volatile char spi_bytes; /* number of bytes to read */ |
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| 14 | static spi_fun_recv_t spi_recv_func; /* byte handler */ |
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| 15 | static spi_fun_recv_complete_t spi_recv_complete_func; /*transmission completion handler */ |
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| 16 | |||
| 17 | /**
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| 18 | * @brief Initialize SPI hardware for communication.
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| 19 | *
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| 20 | * @param recv_func The function to be called for each byte of data received.
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| 21 | * @param recv_complete_func The function to be called at the end of a complete transmission.
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| 22 | 1461 | bneuman | *
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| 23 | * @return 0 if init succesfull, an error code otherwise
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| 24 | 868 | justin | */
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| 25 | 1461 | bneuman | int spi_init (spi_fun_recv_t recv_func, spi_fun_recv_complete_t recv_complete_func)
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| 26 | 868 | justin | {
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| 27 | 1461 | bneuman | if(spi_initd) {
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| 28 | return ERROR_INIT_ALREADY_INITD;
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| 29 | } |
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| 30 | |||
| 31 | 868 | justin | /* Enable Interrupt, Enable SPI Module, MSB First, Master Mode, Clock div = 64 */
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| 32 | SPCR = _BV(SPE) | _BV(SPIE) /*| _BV(DORD)*/ | _BV(MSTR) | _BV(SPR1) | _BV(SPR0);
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| 33 | SPSR = _BV(SPI2X); |
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| 34 | |||
| 35 | /* Set SCLK, SS, MOSI as outputs. MISO as input */
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| 36 | DDRB |= MOSI | SCLK | SS; |
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| 37 | DDRB &= ~MISO; |
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| 38 | |||
| 39 | /* Keep SS high until transmit */
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| 40 | PORTB |= SS; |
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| 41 | |||
| 42 | /* set function to be executed when we receive a byte */
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| 43 | spi_recv_func = recv_func; |
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| 44 | spi_recv_complete_func = recv_complete_func; |
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| 45 | spi_bytes = 0;
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| 46 | //usb_puts("\tspi.c Debug: SPI INITIALIZED\n");
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| 47 | 1461 | bneuman | |
| 48 | spi_initd=1;
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| 49 | return 0; |
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| 50 | 868 | justin | } |
| 51 | |||
| 52 | /**
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| 53 | * @brief Transfer a given byte to slave and receive a byte
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| 54 | *
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| 55 | * @param bytes The number of bytes to be transferred.
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| 56 | **/
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| 57 | 1461 | bneuman | int spi_transfer(char bytes) |
| 58 | 868 | justin | {
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| 59 | 1461 | bneuman | if(!spi_initd)
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| 60 | return ERROR_LIBRARY_NOT_INITD;
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| 61 | |||
| 62 | 868 | justin | spi_bytes = bytes; |
| 63 | PORTB &= ~SS; /* Set SS low to initiate transmission */
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| 64 | SPDR = 0xff; /* Initiate data transmision */ |
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| 65 | 1461 | bneuman | |
| 66 | return 0; |
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| 67 | 868 | justin | } |
| 68 | |||
| 69 | ISR(SIG_SPI) |
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| 70 | {
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| 71 | //usb_puts("Interrupt");
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| 72 | /* only handle intterupt when we are expecting data */
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| 73 | if(spi_bytes > 0){ |
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| 74 | /* process byte */
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| 75 | spi_recv_func(SPDR); |
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| 76 | /* if we've read all the bytes, set SS high to end transmission,
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| 77 | * otherwise get the next byte */
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| 78 | if(--spi_bytes == 0){ |
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| 79 | //usb_puts("Read all bytes\r\n");
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| 80 | PORTB |= SS; |
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| 81 | if(spi_recv_complete_func)
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| 82 | spi_recv_complete_func(); |
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| 83 | }else {
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| 84 | //usb_puts("There are this many bytes left: "); usb_puti(spi_bytes);usb_puts("\r\n");
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| 85 | SPDR = 0xff;
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| 86 | } |
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| 87 | } |
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| 88 | } |