1 /*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 /*
18 * This is an example to set/clear a GPIO pin using the MRAA library.
19 * This may be tested with any of many GPIO devices such as an LED
20 * directly connected to the GPIO pin and ground,
21 * the Grove buzzer or Grove LED board.
22 *
23 * The on-board LED on the Edison Arudino expansion board may be
24 * accessed with Digital I/O 13 (mapped from Linux GPIO 243):
25 * example-gpio-output -p 13 -s
26 *
27 * See the following link for a table to map from the numbers on the
28 * board silk screen to the libmraa GPIO numbers:
29 * https://learn.sparkfun.com/tutorials/installing-libmraa-on-ubilinux-for-edison
30 */
31 #include <getopt.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34
35 #include <mraa.h>
36
37 // Structure to hold the decoded command line options
38 struct pgm_options {
39 int pin;
40 bool set;
41 bool clear;
42 };
43
44 // Be sure to keep the options for longopts and shortopts in the same order
45 // so that Usage() is correct.
46 static struct option longopts[] = {
47 {"help", no_argument, NULL, '?'},
48 {"pin", no_argument, NULL, 'p'},
49 {"set", no_argument, NULL, 's'},
50 {"clear", no_argument, NULL, 'c'},
51 {NULL, 0, NULL, 0 }
52 };
53 static char shortopts[] = "?p:sc";
54
55 // Describes the options for this program.
Usage(char * pgm_name)56 void Usage(char *pgm_name) {
57 printf("Usage: %s [options...]\n", pgm_name);
58 printf("Manipulate a GPIO pin\n");
59 printf("Options:\n");
60 for (int i = 0, j = 0; longopts[i].name; i++, j++) {
61 if (shortopts[j] == ':')
62 j++;
63 printf(" --%-6s%s or -%c%s""\n",
64 longopts[i].name,
65 (shortopts[j+1] == ':') ? " <arg> " : "",
66 shortopts[j],
67 (shortopts[j+1] == ':') ? " <arg> " : "");
68 }
69 return;
70 }
71
72 // Processes all command line options.
73 // sets the options members for commnd line options
74 // returns (0) on success, -1 otherwise.
ReadOpts(int argc,char ** argv,struct pgm_options * options)75 int ReadOpts(int argc, char **argv, struct pgm_options *options) {
76 int ch = 0;
77
78 while ((ch = getopt_long(argc, argv, shortopts, longopts, NULL)) != -1) {
79 switch (ch) {
80 case 'p':
81 options->pin = atoi(optarg);
82 break;
83 case 's':
84 options->set = true;
85 break;
86 case 'c':
87 options->clear = true;
88 break;
89 default:
90 Usage(argv[0]);
91 return -1;
92 }
93 }
94 argc -= optind;
95 argv += optind;
96
97 return 0;
98 }
99
main(int argc,char * argv[])100 int main(int argc, char* argv[]) {
101 const unsigned kDefaultPinGPIO = 7;
102 pgm_options options = {kDefaultPinGPIO, false, false};
103
104 if (ReadOpts(argc, argv, &options) < 0)
105 return 1;
106
107 mraa_init();
108 mraa_gpio_context m_gpio = mraa_gpio_init(options.pin);
109 if (!m_gpio) {
110 fprintf(stderr, "Unable to initialize GPIO, invalid pin number?\n");
111 return 1;
112 }
113 mraa_gpio_dir(m_gpio, MRAA_GPIO_OUT);
114
115 if (options.set)
116 mraa_gpio_write(m_gpio, 1);
117
118 // If both options were specified, wait a few seconds before clearing
119 if (options.clear && options.set)
120 sleep(5);
121
122 if (options.clear)
123 mraa_gpio_write(m_gpio, 0);
124
125 mraa_gpio_close(m_gpio);
126 return 0;
127 }
128