pikeyd165 – Blame information for rev 1
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1 | office | 1 | // spi.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 byte 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 spi spi.c -l bcm2835 |
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9 | // sudo ./spi |
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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 spi -I ../../src ../../src/bcm2835.c spi.c |
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13 | // sudo ./spi |
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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_setBitOrder(BCM2835_SPI_BIT_ORDER_MSBFIRST); // The default |
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40 | bcm2835_spi_setDataMode(BCM2835_SPI_MODE0); // The default |
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41 | bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_65536); // The default |
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42 | bcm2835_spi_chipSelect(BCM2835_SPI_CS0); // The default |
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43 | bcm2835_spi_setChipSelectPolarity(BCM2835_SPI_CS0, LOW); // the default |
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44 | |||
45 | // Send a byte to the slave and simultaneously read a byte back from the slave |
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46 | // If you tie MISO to MOSI, you should read back what was sent |
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47 | uint8_t send_data = 0x23; |
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48 | uint8_t read_data = bcm2835_spi_transfer(send_data); |
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49 | printf("Sent to SPI: 0x%02X. Read back from SPI: 0x%02X.\n", send_data, read_data); |
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50 | if (send_data != read_data) |
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51 | printf("Do you have the loopback from MOSI to MISO connected?\n"); |
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52 | bcm2835_spi_end(); |
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53 | bcm2835_close(); |
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54 | return 0; |
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55 | } |
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56 |