树莓派与arduino通过spi通信

  1 /*
  2  * SPI testing utility (using spidev driver)
  3  *
  4  * Copyright (c) 2007  MontaVista Software, Inc.
  5  * Copyright (c) 2007  Anton Vorontsov <avorontsov@ru.mvista.com>
  6  *
  7  * This program is free software; you can redistribute it and/or modify
  8  * it under the terms of the GNU General Public License as published by
  9  * the Free Software Foundation; either version 2 of the License.
 10  *
 11  * Cross-compile with cross-gcc -I/path/to/cross-kernel/include
 12  */
 13 
 14 #include <stdint.h>
 15 #include <unistd.h>
 16 #include <stdio.h>
 17 #include <stdlib.h>
 18 #include <getopt.h>
 19 #include <fcntl.h>
 20 #include <sys/ioctl.h>
 21 #include <linux/types.h>
 22 #include <linux/spi/spidev.h>
 23 
 24 #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
 25 
 26 static void pabort(const char *s)
 27 {
 28     perror(s);
 29     abort();
 30 }
 31 
 32 static const char *device = "/dev/spidev0.0";
 33 static uint8_t mode;
 34 static uint8_t bits = 8;
 35 static uint32_t speed = 500000;
 36 static uint16_t delay;
 37 
 38 static void transfer(int fd)
 39 {
 40     int ret;
 41     uint8_t tx[] = {
 42         0x48, 0x45, 0x4C, 0x4C, 0x4F,
 43         0x20, 
 44         0x57, 0x4F, 0x52, 0x4C, 0x44,
 45         0x0A 
 46     };
 47     uint8_t rx[ARRAY_SIZE(tx)] = {0, };
 48     struct spi_ioc_transfer tr = {
 49         .tx_buf = (unsigned long)tx,
 50         .rx_buf = (unsigned long)rx,
 51         .len = ARRAY_SIZE(tx),
 52         .delay_usecs = delay,
 53         .speed_hz = speed,
 54         .bits_per_word = bits,
 55     };
 56 
 57     ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
 58     if (ret < 1)
 59         pabort("can‘t send spi message");
 60 
 61     /*
 62     for (ret = 0; ret < ARRAY_SIZE(tx); ret++) {
 63         if (!(ret % 6))
 64             puts("");
 65         printf("%.2X ", rx[ret]);
 66     }
 67     puts("");
 68     */
 69 }
 70 
 71 static void print_usage(const char *prog)
 72 {
 73     printf("Usage: %s [-DsbdlHOLC3]\n", prog);
 74     puts("  -D --device   device to use (default /dev/spidev1.1)\n"
 75          "  -s --speed    max speed (Hz)\n"
 76          "  -d --delay    delay (usec)\n"
 77          "  -b --bpw      bits per word \n"
 78          "  -l --loop     loopback\n"
 79          "  -H --cpha     clock phase\n"
 80          "  -O --cpol     clock polarity\n"
 81          "  -L --lsb      least significant bit first\n"
 82          "  -C --cs-high  chip select active high\n"
 83          "  -3 --3wire    SI/SO signals shared\n");
 84     exit(1);
 85 }
 86 
 87 static void parse_opts(int argc, char *argv[])
 88 {
 89     while (1) {
 90         static const struct option lopts[] = {
 91             { "device",  1, 0, ‘D‘ },
 92             { "speed",   1, 0, ‘s‘ },
 93             { "delay",   1, 0, ‘d‘ },
 94             { "bpw",     1, 0, ‘b‘ },
 95             { "loop",    0, 0, ‘l‘ },
 96             { "cpha",    0, 0, ‘H‘ },
 97             { "cpol",    0, 0, ‘O‘ },
 98             { "lsb",     0, 0, ‘L‘ },
 99             { "cs-high", 0, 0, ‘C‘ },
100             { "3wire",   0, 0, ‘3‘ },
101             { "no-cs",   0, 0, ‘N‘ },
102             { "ready",   0, 0, ‘R‘ },
103             { NULL, 0, 0, 0 },
104         };
105         int c;
106 
107         c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL);
108 
109         if (c == -1)
110             break;
111 
112         switch (c) {
113         case ‘D‘:
114             device = optarg;
115             break;
116         case ‘s‘:
117             speed = atoi(optarg);
118             break;
119         case ‘d‘:
120             delay = atoi(optarg);
121             break;
122         case ‘b‘:
123             bits = atoi(optarg);
124             break;
125         case ‘l‘:
126             mode |= SPI_LOOP;
127             break;
128         case ‘H‘:
129             mode |= SPI_CPHA;
130             break;
131         case ‘O‘:
132             mode |= SPI_CPOL;
133             break;
134         case ‘L‘:
135             mode |= SPI_LSB_FIRST;
136             break;
137         case ‘C‘:
138             mode |= SPI_CS_HIGH;
139             break;
140         case ‘3‘:
141             mode |= SPI_3WIRE;
142             break;
143         case ‘N‘:
144             mode |= SPI_NO_CS;
145             break;
146         case ‘R‘:
147             mode |= SPI_READY;
148             break;
149         default:
150             print_usage(argv[0]);
151             break;
152         }
153     }
154 }
155 
156 int main(int argc, char *argv[])
157 {
158     int ret = 0;
159     int fd;
160 
161     parse_opts(argc, argv);
162 
163     fd = open(device, O_RDWR);
164     if (fd < 0)
165         pabort("can‘t open device");
166 
167     /*
168      * spi mode
169      */
170     ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
171     if (ret == -1)
172         pabort("can‘t set spi mode");
173 
174     ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
175     if (ret == -1)
176         pabort("can‘t get spi mode");
177 
178     /*
179      * bits per word
180      */
181     ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
182     if (ret == -1)
183         pabort("can‘t set bits per word");
184 
185     ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
186     if (ret == -1)
187         pabort("can‘t get bits per word");
188 
189     /*
190      * max speed hz
191      */
192     ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
193     if (ret == -1)
194         pabort("can‘t set max speed hz");
195 
196     ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
197     if (ret == -1)
198         pabort("can‘t get max speed hz");
199 
200     printf("spi mode: %d\n", mode);
201     printf("bits per word: %d\n", bits);
202     printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);
203 
204     transfer(fd);
205 
206     close(fd);
207 
208     return ret;
209 }

 1 // Written by Nick Gammon
 2 // February 2011
 3 
 4 
 5 #include <SPI.h>
 6 
 7 char buf [100];
 8 volatile byte pos;
 9 volatile boolean process_it;
10 
11 void setup (void)
12 {
13   Serial.begin (115200);   // debugging
14 
15   // have to send on master in, *slave out*
16   pinMode(MISO, OUTPUT);
17   
18   // turn on SPI in slave mode
19   SPCR |= _BV(SPE);
20   
21   // get ready for an interrupt 
22   pos = 0;   // buffer empty
23   process_it = false;
24 
25   // now turn on interrupts
26   SPI.attachInterrupt();
27 
28 }  // end of setup
29 
30 
31 // SPI interrupt routine
32 ISR (SPI_STC_vect)
33 {
34 byte c = SPDR;  // grab byte from SPI Data Register
35   
36   // add to buffer if room
37   if (pos < sizeof buf)
38     {
39     buf [pos++] = c;
40     
41     // example: newline means time to process buffer
42     if (c == ‘\n‘)
43       process_it = true;
44       
45     }  // end of room available
46 }  // end of interrupt routine SPI_STC_vect
47 
48 // main loop - wait for flag set in interrupt routine
49 void loop (void)
50 {
51   if (process_it)
52     {
53     buf [pos] = 0;  
54     Serial.println (buf);
55     pos = 0;
56     process_it = false;
57     }  // end of flag set
58     
59 }  // end of loopang