Replace tool examples with use case examples drawn from the tools.
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
# SPDX-License-Identifier: GPL-2.0-or-later
# SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
-gpiodetectcxx
-gpiofindcxx
-gpiogetcxx
-gpioinfocxx
-gpiomoncxx
-gpionotifycxx
-gpiosetcxx
async_watch_line_value
+find_line_by_name
+get_chip_info
+get_line_info
get_line_value
+get_multiple_line_values
+reconfigure_input_to_output
toggle_line_value
+toggle_multiple_line_values
+watch_line_info
+watch_line_rising
watch_line_value
+watch_multiple_line_values
AM_LDFLAGS = -lgpiodcxx -L$(top_builddir)/bindings/cxx/
noinst_PROGRAMS = \
- gpiodetectcxx \
- gpiofindcxx \
- gpiogetcxx \
- gpioinfocxx \
- gpiomoncxx \
- gpionotifycxx \
- gpiosetcxx \
async_watch_line_value \
+ find_line_by_name \
+ get_chip_info \
+ get_line_info \
get_line_value \
+ get_multiple_line_values \
+ reconfigure_input_to_output \
toggle_line_value \
- watch_line_value
+ toggle_multiple_line_values \
+ watch_line_info \
+ watch_line_rising \
+ watch_line_value \
+ watch_multiple_line_values
-gpiodetectcxx_SOURCES = gpiodetectcxx.cpp
+async_watch_line_value_SOURCES = async_watch_line_value.cpp
-gpiofindcxx_SOURCES = gpiofindcxx.cpp
+find_line_by_name_SOURCES = find_line_by_name.cpp
-gpiogetcxx_SOURCES = gpiogetcxx.cpp
+get_chip_info_SOURCES = get_chip_info.cpp
-gpioinfocxx_SOURCES = gpioinfocxx.cpp
+get_line_info_SOURCES = get_line_info.cpp
-gpiomoncxx_SOURCES = gpiomoncxx.cpp
+get_line_value_SOURCES = get_line_value.cpp
-gpionotifycxx_SOURCES = gpionotifycxx.cpp
+get_multiple_line_values_SOURCES = get_multiple_line_values.cpp
-gpiosetcxx_SOURCES = gpiosetcxx.cpp
+reconfigure_input_to_output_SOURCES = reconfigure_input_to_output.cpp
-async_watch_line_value_SOURCES = async_watch_line_value.cpp
+toggle_line_value_SOURCES = toggle_line_value.cpp
-get_line_value_SOURCES = get_line_value.cpp
+toggle_multiple_line_values_SOURCES = toggle_multiple_line_values.cpp
-toggle_line_value_SOURCES = toggle_line_value.cpp
+watch_line_info_SOURCES = watch_line_info.cpp
watch_line_value_SOURCES = watch_line_value.cpp
+
+watch_line_rising_SOURCES = watch_line_rising.cpp
+
+watch_multiple_line_values_SOURCES = watch_multiple_line_values.cpp
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of finding a line with the given name. */
+
+#include <cstdlib>
+#include <filesystem>
+#include <gpiod.hpp>
+#include <iostream>
+
+namespace {
+
+/* Example configuration - customize to suit your situation */
+const ::std::string line_name = "GPIO19";
+
+} /* namespace */
+
+int main(void)
+{
+ /*
+ * Names are not guaranteed unique, so this finds the first line with
+ * the given name.
+ */
+ for (const auto &entry :
+ ::std::filesystem::directory_iterator("/dev/")) {
+ if (::gpiod::is_gpiochip_device(entry.path())) {
+ ::gpiod::chip chip(entry.path());
+
+ auto offset = chip.get_line_offset_from_name(line_name);
+ if (offset >= 0) {
+ ::std::cout << line_name << ": "
+ << chip.get_info().name() << " "
+ << offset << ::std::endl;
+ return EXIT_SUCCESS;
+ }
+ }
+ }
+ ::std::cout << "line '" << line_name << "' not found" << ::std::endl;
+
+ return EXIT_FAILURE;
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of reading the info for a chip. */
+
+#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");
+
+} /* namespace */
+
+int main(void)
+{
+ ::gpiod::chip chip(chip_path);
+ auto info = chip.get_info();
+
+ ::std::cout << info.name() << " [" << info.label() << "] ("
+ << info.num_lines() << " lines)" << ::std::endl;
+
+ return EXIT_SUCCESS;
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of reading the info for a line. */
+
+#include <cstdlib>
+#include <filesystem>
+#include <gpiod.hpp>
+#include <iomanip>
+#include <iostream>
+
+namespace {
+
+/* Example configuration - customize to suit your situation */
+const ::std::filesystem::path chip_path("/dev/gpiochip0");
+const ::gpiod::line::offset line_offset = 3;
+
+} /* namespace */
+
+int main(void)
+{
+ auto chip = ::gpiod::chip(chip_path);
+ auto info = chip.get_line_info(line_offset);
+
+ ::std::cout << "line " << ::std::setw(3) << info.offset() << ": "
+ << ::std::setw(12)
+ << (info.name().empty() ? "unnamed" : info.name()) << " "
+ << ::std::setw(12)
+ << (info.consumer().empty() ? "unused" : info.consumer())
+ << " " << ::std::setw(8)
+ << (info.direction() == ::gpiod::line::direction::INPUT ?
+ "input" :
+ "output")
+ << " " << ::std::setw(10)
+ << (info.active_low() ? "active-low" : "active-high")
+ << ::std::endl;
+
+ return EXIT_SUCCESS;
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of reading multiple lines. */
+
+#include <cstdlib>
+#include <gpiod.hpp>
+#include <iostream>
+
+namespace {
+
+/* Example configuration - customize to suit your situation */
+const ::std::filesystem::path chip_path("/dev/gpiochip0");
+const ::gpiod::line::offsets line_offsets = { 5, 3, 7 };
+
+} /* namespace */
+
+int main(void)
+{
+ auto request = ::gpiod::chip(chip_path)
+ .prepare_request()
+ .set_consumer("get-multiple-line-values")
+ .add_line_settings(
+ line_offsets,
+ ::gpiod::line_settings().set_direction(
+ ::gpiod::line::direction::INPUT))
+ .do_request();
+
+ auto values = request.get_values();
+
+ for (size_t i = 0; i < line_offsets.size(); i++)
+ ::std::cout << line_offsets[i] << "="
+ << (values[i] == ::gpiod::line::value::ACTIVE ?
+ "Active" :
+ "Inactive")
+ << ' ';
+ ::std::cout << ::std::endl;
+
+ return EXIT_SUCCESS;
+}
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-// SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
-
-/* C++ reimplementation of the gpiodetect tool. */
-
-#include <cstdlib>
-#include <filesystem>
-#include <gpiod.hpp>
-#include <iostream>
-
-int main(int argc, char **argv)
-{
- if (argc != 1) {
- ::std::cerr << "usage: " << argv[0] << ::std::endl;
- return EXIT_FAILURE;
- }
-
- for (const auto& entry: ::std::filesystem::directory_iterator("/dev/")) {
- if (::gpiod::is_gpiochip_device(entry.path())) {
- ::gpiod::chip chip(entry.path());
- auto info = chip.get_info();
-
- ::std::cout << info.name() << " [" <<
- info.label() << "] (" <<
- info.num_lines() << " lines)" << ::std::endl;
- }
- }
-
- return EXIT_SUCCESS;
-}
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-// SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
-
-/* C++ reimplementation of the gpiofind tool. */
-
-#include <gpiod.hpp>
-
-#include <cstdlib>
-#include <filesystem>
-#include <iostream>
-
-int main(int argc, char **argv)
-{
- if (argc != 2) {
- ::std::cerr << "usage: " << argv[0] << " <line name>" << ::std::endl;
- return EXIT_FAILURE;
- }
-
- for (const auto& entry: ::std::filesystem::directory_iterator("/dev/")) {
- if (::gpiod::is_gpiochip_device(entry.path())) {
- ::gpiod::chip chip(entry.path());
-
- auto offset = chip.get_line_offset_from_name(argv[1]);
- if (offset >= 0) {
- ::std::cout << chip.get_info().name() << " " << offset << ::std::endl;
- return EXIT_SUCCESS;
- }
- }
- }
-
- return EXIT_FAILURE;
-}
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-// SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
-
-/* Simplified C++ reimplementation of the gpioget tool. */
-
-#include <gpiod.hpp>
-
-#include <cstdlib>
-#include <iostream>
-
-int main(int argc, char **argv)
-{
- if (argc < 3) {
- ::std::cerr << "usage: " << argv[0] << " <chip> <line_offset0> ..." << ::std::endl;
- return EXIT_FAILURE;
- }
-
- ::gpiod::line::offsets offsets;
-
- for (int i = 2; i < argc; i++)
- offsets.push_back(::std::stoul(argv[i]));
-
- auto request = ::gpiod::chip(argv[1])
- .prepare_request()
- .set_consumer("gpiogetcxx")
- .add_line_settings(
- offsets,
- ::gpiod::line_settings()
- .set_direction(::gpiod::line::direction::INPUT)
- )
- .do_request();
-
- auto vals = request.get_values();
-
- for (auto& it: vals)
- ::std::cout << (it == ::gpiod::line::value::ACTIVE ? "1" : "0") << ' ';
- ::std::cout << ::std::endl;
-
- return EXIT_SUCCESS;
-}
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-// SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
-
-/* Simplified C++ reimplementation of the gpioinfo tool. */
-
-#include <gpiod.hpp>
-
-#include <cstdlib>
-#include <filesystem>
-#include <iostream>
-
-namespace {
-
-void show_chip(const ::gpiod::chip& chip)
-{
- auto info = chip.get_info();
-
- ::std::cout << info.name() << " - " << info.num_lines() << " lines:" << ::std::endl;
-
- for (unsigned int offset = 0; offset < info.num_lines(); offset++) {
- auto info = chip.get_line_info(offset);
-
- ::std::cout << "\tline ";
- ::std::cout.width(3);
- ::std::cout << info.offset() << ": ";
-
- ::std::cout.width(12);
- ::std::cout << (info.name().empty() ? "unnamed" : info.name());
- ::std::cout << " ";
-
- ::std::cout.width(12);
- ::std::cout << (info.consumer().empty() ? "unused" : info.consumer());
- ::std::cout << " ";
-
- ::std::cout.width(8);
- ::std::cout << (info.direction() == ::gpiod::line::direction::INPUT ? "input" : "output");
- ::std::cout << " ";
-
- ::std::cout.width(10);
- ::std::cout << (info.active_low() ? "active-low" : "active-high");
-
- ::std::cout << ::std::endl;
- }
-}
-
-} /* namespace */
-
-int main(int argc, char **argv)
-{
- if (argc != 1) {
- ::std::cerr << "usage: " << argv[0] << ::std::endl;
- return EXIT_FAILURE;
- }
-
- for (const auto& entry: ::std::filesystem::directory_iterator("/dev/")) {
- if (::gpiod::is_gpiochip_device(entry.path()))
- show_chip(::gpiod::chip(entry.path()));
- }
-
- return EXIT_SUCCESS;
-}
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-// SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
-
-/* Simplified C++ reimplementation of the gpiomon tool. */
-
-#include <cstdlib>
-#include <gpiod.hpp>
-#include <iostream>
-
-namespace {
-
-void print_event(const ::gpiod::edge_event& event)
-{
- if (event.type() == ::gpiod::edge_event::event_type::RISING_EDGE)
- ::std::cout << " RISING EDGE";
- else
- ::std::cout << "FALLING EDGE";
-
- ::std::cout << " ";
-
- ::std::cout << event.timestamp_ns() / 1000000000;
- ::std::cout << ".";
- ::std::cout << event.timestamp_ns() % 1000000000;
-
- ::std::cout << " line: " << event.line_offset();
-
- ::std::cout << ::std::endl;
-}
-
-} /* namespace */
-
-int main(int argc, char **argv)
-{
- if (argc < 3) {
- ::std::cout << "usage: " << argv[0] << " <chip> <offset0> ..." << ::std::endl;
- return EXIT_FAILURE;
- }
-
- ::gpiod::line::offsets offsets;
- offsets.reserve(argc - 2);
- for (int i = 2; i < argc; i++)
- offsets.push_back(::std::stoul(argv[i]));
-
- auto request = ::gpiod::chip(argv[1])
- .prepare_request()
- .set_consumer("gpiomoncxx")
- .add_line_settings(
- offsets,
- ::gpiod::line_settings()
- .set_direction(::gpiod::line::direction::INPUT)
- .set_edge_detection(::gpiod::line::edge::BOTH)
- )
- .do_request();
-
- ::gpiod::edge_event_buffer buffer;
-
- for (;;) {
- request.read_edge_events(buffer);
-
- for (const auto& event: buffer)
- print_event(event);
- }
-
- return EXIT_SUCCESS;
-}
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-// SPDX-FileCopyrightText: 2023 Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
-
-/* Simplified C++ reimplementation of the gpionotify tool. */
-
-#include <cstdlib>
-#include <gpiod.hpp>
-#include <iostream>
-
-namespace {
-
-void print_event(const ::gpiod::info_event& event)
-{
- switch (event.type()) {
- case ::gpiod::info_event::event_type::LINE_REQUESTED:
- ::std::cout << "LINE REQUESTED";
- break;
- case ::gpiod::info_event::event_type::LINE_RELEASED:
- ::std::cout << "LINE RELEASED";
- break;
- case ::gpiod::info_event::event_type::LINE_CONFIG_CHANGED:
- ::std::cout << "CONFIG CHANGED";
- break;
- }
-
- ::std::cout << " ";
-
- ::std::cout << event.timestamp_ns() / 1000000000;
- ::std::cout << ".";
- ::std::cout << event.timestamp_ns() % 1000000000;
-
- ::std::cout << " line: " << event.get_line_info().offset();
-
- ::std::cout << ::std::endl;
-}
-
-} /* namespace */
-
-int main(int argc, char **argv)
-{
- if (argc < 3) {
- ::std::cout << "usage: " << argv[0] << " <chip> <offset0> ..." << ::std::endl;
- return EXIT_FAILURE;
- }
-
- ::gpiod::chip chip(argv[1]);
-
- for (int i = 2; i < argc; i++)
- chip.watch_line_info(::std::stoul(argv[i]));
-
- for (;;)
- print_event(chip.read_info_event());
-
- return EXIT_SUCCESS;
-}
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-// SPDX-FileCopyrightText: 2017-2021 Bartosz Golaszewski <bartekgola@gmail.com>
-
-/* Simplified C++ reimplementation of the gpioset tool. */
-
-#include <gpiod.hpp>
-
-#include <cstdlib>
-#include <iostream>
-
-int main(int argc, char **argv)
-{
- if (argc < 3) {
- ::std::cerr << "usage: " << argv[0] <<
- " <chip> <line_offset0>=<value0> ..." << ::std::endl;
- return EXIT_FAILURE;
- }
-
- ::gpiod::line::offsets offsets;
- ::gpiod::line::values values;
-
- for (int i = 2; i < argc; i++) {
- ::std::string arg(argv[i]);
-
- size_t pos = arg.find('=');
-
- ::std::string offset(arg.substr(0, pos));
- ::std::string value(arg.substr(pos + 1, ::std::string::npos));
-
- if (offset.empty() || value.empty())
- throw ::std::invalid_argument("invalid offset=value mapping: " +
- ::std::string(argv[i]));
-
- offsets.push_back(::std::stoul(offset));
- values.push_back(::std::stoul(value) ? ::gpiod::line::value::ACTIVE :
- ::gpiod::line::value::INACTIVE);
- }
-
- auto request = ::gpiod::chip(argv[1])
- .prepare_request()
- .set_consumer("gpiosetcxx")
- .add_line_settings(
- offsets,
- ::gpiod::line_settings()
- .set_direction(::gpiod::line::direction::OUTPUT)
- )
- .set_output_values(values)
- .do_request();
-
- ::std::cin.get();
-
- return EXIT_SUCCESS;
-}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/*
+ * Minimal example of requesting a line intended for bi-directional use as
+ * input and then switching to output.
+ */
+
+#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(void)
+{
+ /* request the line initially as an input */
+ auto request = ::gpiod::chip(chip_path)
+ .prepare_request()
+ .set_consumer("reconfigure-input-to-output")
+ .add_line_settings(
+ line_offset,
+ ::gpiod::line_settings().set_direction(
+ ::gpiod::line::direction::INPUT))
+ .do_request();
+
+ /* read the current line value */
+ ::std::cout << line_offset << "="
+ << (request.get_value(line_offset) ==
+ ::gpiod::line::value::ACTIVE ?
+ "Active" :
+ "Inactive")
+ << " (input)" << ::std::endl;
+
+ /* switch the line to an output and drive it low */
+ request.reconfigure_lines(::gpiod::line_config().add_line_settings(
+ line_offset,
+ ::gpiod::line_settings()
+ .set_direction(::gpiod::line::direction::OUTPUT)
+ .set_output_value(::gpiod::line::value::INACTIVE)));
+
+ /* report the current driven value */
+ ::std::cout << line_offset << "="
+ << (request.get_value(line_offset) ==
+ ::gpiod::line::value::ACTIVE ?
+ "Active" :
+ "Inactive")
+ << " (output)" << ::std::endl;
+
+ return EXIT_SUCCESS;
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of toggling multiple lines. */
+
+#include <cstdlib>
+#include <gpiod.hpp>
+#include <iostream>
+#include <thread>
+
+namespace {
+
+/* Example configuration - customize to suit your situation */
+const ::std::filesystem::path chip_path("/dev/gpiochip0");
+const ::gpiod::line::offsets line_offsets = { 5, 3, 7 };
+
+::gpiod::line::value toggle_value(::gpiod::line::value v)
+{
+ return (v == ::gpiod::line::value::ACTIVE) ?
+ ::gpiod::line::value::INACTIVE :
+ ::gpiod::line::value::ACTIVE;
+}
+
+void toggle_values(::gpiod::line::values &values)
+{
+ for (size_t i = 0; i < values.size(); i++)
+ values[i] = toggle_value(values[i]);
+}
+
+void print_values(::gpiod::line::offsets const &offsets,
+ ::gpiod::line::values const &values)
+{
+ for (size_t i = 0; i < offsets.size(); i++)
+ ::std::cout << offsets[i] << "=" << values[i] << ' ';
+ ::std::cout << ::std::endl;
+}
+
+} /* namespace */
+
+int main(void)
+{
+ ::gpiod::line::values values = { ::gpiod::line::value::ACTIVE,
+ ::gpiod::line::value::ACTIVE,
+ ::gpiod::line::value::INACTIVE };
+
+ auto request =
+ ::gpiod::chip(chip_path)
+ .prepare_request()
+ .set_consumer("toggle-multiple-line-values")
+ .add_line_settings(
+ line_offsets,
+ ::gpiod::line_settings().set_direction(
+ ::gpiod::line::direction::OUTPUT))
+ .set_output_values(values)
+ .do_request();
+
+ for (;;) {
+ print_values(line_offsets, values);
+ std::this_thread::sleep_for(std::chrono::seconds(1));
+ toggle_values(values);
+ request.set_values(line_offsets, values);
+ }
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of watching for requests on particular lines. */
+
+#include <cstdlib>
+#include <gpiod.hpp>
+#include <iomanip>
+#include <iostream>
+
+namespace {
+
+/* Example configuration - customize to suit your situation. */
+const ::std::filesystem::path chip_path("/dev/gpiochip0");
+const ::gpiod::line::offsets line_offsets = { 5, 3, 7 };
+
+const char *event_type(const ::gpiod::info_event &event)
+{
+ switch (event.type()) {
+ case ::gpiod::info_event::event_type::LINE_REQUESTED:
+ return "Requested";
+ case ::gpiod::info_event::event_type::LINE_RELEASED:
+ return "Released";
+ case ::gpiod::info_event::event_type::LINE_CONFIG_CHANGED:
+ return "Reconfig";
+ default:
+ return "Unknown";
+ }
+}
+
+} /* namespace */
+
+int main(void)
+{
+ ::gpiod::chip chip(chip_path);
+
+ for (auto offset :line_offsets)
+ chip.watch_line_info(offset);
+
+ for (;;) {
+ /* Blocks until at least one event is available */
+ auto event = chip.read_info_event();
+ ::std::cout << "line: " << event.get_line_info().offset() << " "
+ << ::std::setw(9) << ::std::left
+ << event_type(event) << " "
+ << event.timestamp_ns() / 1000000000 << "."
+ << event.timestamp_ns() % 1000000000 << ::std::endl;
+ }
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of watching for rising edges on a single line. */
+
+#include <cstdlib>
+#include <filesystem>
+#include <gpiod.hpp>
+#include <iomanip>
+#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;
+
+const char *edge_event_type_str(const ::gpiod::edge_event &event)
+{
+ switch (event.type()) {
+ case ::gpiod::edge_event::event_type::RISING_EDGE:
+ return "Rising";
+ case ::gpiod::edge_event::event_type::FALLING_EDGE:
+ return "Falling";
+ default:
+ return "Unknown";
+ }
+}
+
+} /* namespace */
+
+int main(void)
+{
+ auto request =
+ ::gpiod::chip(chip_path)
+ .prepare_request()
+ .set_consumer("watch-line-value")
+ .add_line_settings(
+ line_offset,
+ ::gpiod::line_settings()
+ .set_direction(
+ ::gpiod::line::direction::INPUT)
+ .set_edge_detection(
+ ::gpiod::line::edge::RISING)
+ )
+ .do_request();
+
+ /*
+ * A larger buffer is an optimisation for reading bursts of events from
+ * the kernel, but that is not necessary in this case, so 1 is fine.
+ */
+ ::gpiod::edge_event_buffer buffer(1);
+
+ for (;;) {
+ /* Blocks until at least one event is available. */
+ request.read_edge_events(buffer);
+
+ for (const auto &event : buffer)
+ ::std::cout << "line: " << event.line_offset()
+ << " type: " << ::std::setw(7) << ::std::left << edge_event_type_str(event)
+ << " event #" << event.line_seqno()
+ << ::std::endl;
+ }
+}
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
+
+/* Minimal example of watching for edges on multiple lines. */
+
+#include <cstdlib>
+#include <gpiod.hpp>
+#include <iomanip>
+#include <iostream>
+
+namespace {
+
+/* Example configuration - customize to suit your situation */
+const ::std::filesystem::path chip_path("/dev/gpiochip0");
+const ::gpiod::line::offsets line_offsets = { 5, 3, 7 };
+
+const char *edge_event_type_str(const ::gpiod::edge_event &event)
+{
+ switch (event.type()) {
+ case ::gpiod::edge_event::event_type::RISING_EDGE:
+ return "Rising";
+ case ::gpiod::edge_event::event_type::FALLING_EDGE:
+ return "Falling";
+ default:
+ return "Unknown";
+ }
+}
+
+} /* namespace */
+
+int main(void)
+{
+ auto request =
+ ::gpiod::chip(chip_path)
+ .prepare_request()
+ .set_consumer("watch-multiple-line-values")
+ .add_line_settings(
+ line_offsets,
+ ::gpiod::line_settings()
+ .set_direction(
+ ::gpiod::line::direction::INPUT)
+ .set_edge_detection(
+ ::gpiod::line::edge::BOTH))
+ .do_request();
+
+ ::gpiod::edge_event_buffer buffer;
+
+ for (;;) {
+ /* Blocks until at leat one event available */
+ request.read_edge_events(buffer);
+
+ for (const auto &event : buffer)
+ ::std::cout << "offset: " << event.line_offset()
+ << " type: " << ::std::setw(7)
+ << ::std::left << edge_event_type_str(event)
+ << " event #" << event.global_seqno()
+ << " line event #" << event.line_seqno()
+ << ::std::endl;
+ }
+}
projects / qemu-gpiodev / libgpiod.git / commitdiff