Template:LIBGPIOD V2 C EXAMPLE: Difference between revisions

Latest revision as of 19:52, 10 March 2025

libgpiod C++ Application

[ libgpiod] provides bindings for C++, Python and Rust applications. C++ examples are available in the libgpiod [/tree/bindings/cxx/examples /tree/bindings/cxx/examples ] directory.

Below is a simple C application demonstrating how to use the bindings with GPIO0_IO05:

Makefile:

LDFLAGS = -lgpiodcxx -lgpiod

# Nome do executável e arquivos fonte
TARGET = main
SRCS = main.cpp

all: $(TARGET)

$(TARGET): $(SRCS)
	$(CXX) $(SRCS) $(LDFLAGS) -o $(TARGET)

clean:
	rm -f $(TARGET)

main.cpp

// SPDX-License-Identifier: GPL-2.0-or-later
// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>

/* Minimal example of reading a single line. */

#include <cstdlib>
#include <filesystem>
#include <gpiod.hpp>
#include <iostream>

namespace {

/* Example configuration - customize to suit your situation */
const ::std::filesystem::path chip_path("/dev/gpiochip0");
const ::gpiod::line::offset line_offset = 5;

} /* namespace */

int main()
{
	auto request = ::gpiod::chip(chip_path)
			       .prepare_request()
			       .set_consumer("get-line-value")
			       .add_line_settings(
				       line_offset,
				       ::gpiod::line_settings().set_direction(
					       ::gpiod::line::direction::INPUT))
			       .do_request();

	::std::cout << line_offset << "="
		    << (request.get_value(line_offset) ==
					::gpiod::line::value::ACTIVE ?
				"Active" :
				"Inactive")
		    << ::std::endl;

	return EXIT_SUCCESS;
}

@@ Line 1: / Line 1: @@
-== libgpiod C Application ==
+== libgpiod C++ Application ==
-[{{#var:LIBGPIOD_URL}} libgpiod] provides bindings for C/C++ applications. C++ examples are available in the libgpiod [{{#var:LIBGPIOD_URL}}/tree/bindings/cxx/examples /tree/bindings/cxx/examples ] directory.
+[{{#var:LIBGPIOD_URL}} libgpiod] provides bindings for C++, Python and Rust applications. C++ examples are available in the libgpiod [{{#var:LIBGPIOD_URL}}/tree/bindings/cxx/examples /tree/bindings/cxx/examples ] directory.
-Below is a simple C application demonstrating how to use the bindings with GPIO4_IO21:
+Below is a simple C application demonstrating how to use the bindings with GPIO0_IO05:
 '''Makefile:'''
- all: main.cpp
+<pre>
- 	$(CC) $(CCFLAGS) -Og -lgpiod main.c -g -o hello.bin
+LDFLAGS = -lgpiodcxx -lgpiod
- clean:
- 	rm -f hello.bin
+# Nome do executável e arquivos fonte
+TARGET = main
+SRCS = main.cpp
+all: $(TARGET)
+$(TARGET): $(SRCS)
+	$(CXX) $(SRCS) $(LDFLAGS) -o $(TARGET)
+clean:
+	rm -f $(TARGET)
+</pre>
-'''main.c'''
+'''main.cpp'''
 <pre>
-#include <gpiod.h>
+// SPDX-License-Identifier: GPL-2.0-or-later
-#include <stdio.h>
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
-#include <unistd.h>
-#include <stdlib.h>
+/* Minimal example of reading a single line. */
-#include <string.h>
-#define    CONSUMER    "Variscite Demo"
+#include <cstdlib>
+#include <filesystem>
+#include <gpiod.hpp>
+#include <iostream>
-int main(int argc, char **argv)
+namespace {
-{
-    unsigned int i, ret, val;
-    struct gpiod_chip *chip;
-    struct gpiod_line *line;
-    const char * chipname = "gpiochip3";
-    const unsigned int line_num = 21;
-    chip = gpiod_chip_open_by_name(chipname);
+/* Example configuration - customize to suit your situation */
-    if (!chip) {
+const ::std::filesystem::path chip_path("/dev/gpiochip0");
-        perror("Open chip failed\n");
+const ::gpiod::line::offset line_offset = 5;
-        goto end;
-    }
-    line = gpiod_chip_get_line(chip, line_num);
+} /* namespace */
-    if (!line) {
-        perror("Get line failed\n");
-        goto close_chip;
-    }
-    ret = gpiod_line_request_output(line, CONSUMER, 0);
+int main()
-    if (ret < 0) {
+{
-        perror("Request line as output failed\n");
+	auto request = ::gpiod::chip(chip_path)
-        goto release_line;
+			       .prepare_request()
-    }
+			       .set_consumer("get-line-value")
+			       .add_line_settings(
+				       line_offset,
+				       ::gpiod::line_settings().set_direction(
+					       ::gpiod::line::direction::INPUT))
+			       .do_request();
-    /* Blink 5 times */
+	::std::cout << line_offset << "="
-    val = 0;
+		    << (request.get_value(line_offset) ==
-    for (i = 0; i < 5; i++) {
+					::gpiod::line::value::ACTIVE ?
-        ret = gpiod_line_set_value(line, val);
+				"Active" :
-        if (ret < 0) {
+				"Inactive")
-            perror("Set line output failed\n");
+		    << ::std::endl;
-            goto release_line;
-        }
-        printf("Output %u on line #%u\n", val, line_num);
-        sleep(1);
-        val = !val;
-    }
-release_line:
+	return EXIT_SUCCESS;
-    gpiod_line_release(line);
-close_chip:
-    gpiod_chip_close(chip);
-end:
-    return 0;
 }
 </pre>