pikeyd165 – Blame information for rev 1
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| Rev | Author | Line No. | Line |
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| 1 | office | 1 | // spin.c |
| 2 | // |
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| 3 | // Example program for bcm2835 library |
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| 4 | // Shows how to interface with SPI to transfer a number of bytes to and from an SPI device |
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| 5 | // |
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| 6 | // After installing bcm2835, you can build this |
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| 7 | // with something like: |
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| 8 | // gcc -o spin spin.c -l bcm2835 |
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| 9 | // sudo ./spin |
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| 10 | // |
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| 11 | // Or you can test it before installing with: |
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| 12 | // gcc -o spin -I ../../src ../../src/bcm2835.c spin.c |
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| 13 | // sudo ./spin |
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| 14 | // |
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| 15 | // Author: Mike McCauley |
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| 16 | // Copyright (C) 2012 Mike McCauley |
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| 17 | // $Id: RF22.h,v 1.21 2012/05/30 01:51:25 mikem Exp $ |
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| 18 | |||
| 19 | #include <bcm2835.h> |
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| 20 | #include <stdio.h> |
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| 21 | |||
| 22 | int main(int argc, char **argv) |
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| 23 | { |
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| 24 | // If you call this, it will not actually access the GPIO |
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| 25 | // Use for testing |
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| 26 | // bcm2835_set_debug(1); |
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| 27 | |||
| 28 | if (!bcm2835_init()) |
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| 29 | { |
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| 30 | printf("bcm2835_init failed. Are you running as root??\n"); |
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| 31 | return 1; |
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| 32 | } |
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| 33 | |||
| 34 | if (!bcm2835_spi_begin()) |
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| 35 | { |
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| 36 | printf("bcm2835_spi_begin failed. Are you running as root??\n"); |
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| 37 | return 1; |
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| 38 | } |
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| 39 | bcm2835_spi_begin(); |
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| 40 | bcm2835_spi_setBitOrder(BCM2835_SPI_BIT_ORDER_MSBFIRST); // The default |
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| 41 | bcm2835_spi_setDataMode(BCM2835_SPI_MODE0); // The default |
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| 42 | bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_65536); // The default |
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| 43 | bcm2835_spi_chipSelect(BCM2835_SPI_CS0); // The default |
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| 44 | bcm2835_spi_setChipSelectPolarity(BCM2835_SPI_CS0, LOW); // the default |
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| 45 | |||
| 46 | // Send a some bytes to the slave and simultaneously read |
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| 47 | // some bytes back from the slave |
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| 48 | // Most SPI devices expect one or 2 bytes of command, after which they will send back |
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| 49 | // some data. In such a case you will have the command bytes first in the buffer, |
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| 50 | // followed by as many 0 bytes as you expect returned data bytes. After the transfer, you |
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| 51 | // Can the read the reply bytes from the buffer. |
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| 52 | // If you tie MISO to MOSI, you should read back what was sent. |
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| 53 | |||
| 54 | char buf[] = { 0x01, 0x02, 0x11, 0x33 }; // Data to send |
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| 55 | bcm2835_spi_transfern(buf, sizeof(buf)); |
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| 56 | // buf will now be filled with the data that was read from the slave |
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| 57 | printf("Read from SPI: %02X %02X %02X %02X \n", buf[0], buf[1], buf[2], buf[3]); |
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| 58 | |||
| 59 | bcm2835_spi_end(); |
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| 60 | bcm2835_close(); |
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| 61 | return 0; |
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| 62 | } |
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| 63 |