pps_capture: implementation of pulse per second capture driver

msg/CMakeLists.txt

@@ -118,6 +118,7 @@ set(msg_files
 	orbit_status.msg
 	parameter_update.msg
 	ping.msg
+	pps_capture.msg
 	position_controller_landing_status.msg
 	position_controller_status.msg
 	position_setpoint.msg

msg/pps_capture.msg

@@ -0,0 +1,3 @@
+uint64 timestamp			# time since system start (microseconds)
+uint64 rtc_timestamp		# captured time in microseconds from real-time clock at PPS event
+int32 rtc_drift_time		# time drift between RTC and PPS event in microseconds

src/drivers/pps_capture/CMakeLists.txt

@@ -0,0 +1,38 @@
+############################################################################
+#
+#   Copyright (c) 2021 PX4 Development Team. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name PX4 nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+px4_add_module(
+	MODULE drivers__pps_capture
+	MAIN pps_capture
+	SRCS
+		PPSCapture.cpp
+	)

src/drivers/pps_capture/PPSCapture.cpp

@@ -0,0 +1,155 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2021 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file PPSCapture.cpp
+ *
+ * This is driver for capturing GNSS Pulse Per Second (PPS) signal.
+ *
+ */
+
+#include "PPSCapture.hpp"
+#include "board_config.h"
+
+PPSCapture::PPSCapture() :
+	ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::hp_default)
+{
+}
+
+PPSCapture::~PPSCapture()
+{
+	px4_arch_gpiosetevent(BOARD_CAPTURE_GPIO, false, false, false, nullptr, nullptr);
+}
+
+bool PPSCapture::init()
+{
+	bool success = false;
+
+	int ret_val = px4_arch_gpiosetevent(BOARD_CAPTURE_GPIO, true, false, true, &PPSCapture::gpio_interrupt_callback, this);
+
+	if (ret_val == PX4_OK) {
+		success = true;
+	}
+
+	return success;
+}
+
+void PPSCapture::Run()
+{
+	if (should_exit()) {
+		exit_and_cleanup();
+		return;
+	}
+
+	pps_capture_s pps_capture;
+	pps_capture.timestamp = hrt_absolute_time();
+	pps_capture.rtc_timestamp = ts_to_abstime(&_rtc_system_time);
+	uint32_t microseconds_part = pps_capture.rtc_timestamp % USEC_IN_1_SEC;
+
+	/* max drift time to detect with PPS is in the range between -0.5 s to +0.5 s */
+	pps_capture.rtc_drift_time = (microseconds_part >= MAX_POSITIVE_DRIFT) ? ((-1 * USEC_IN_1_SEC) + microseconds_part)
+				     : microseconds_part;
+	_pps_capture_pub.publish(pps_capture);
+}
+
+int PPSCapture::gpio_interrupt_callback(int irq, void *context, void *arg)
+{
+	PPSCapture *instance = static_cast<PPSCapture *>(arg);
+
+	px4_clock_gettime(CLOCK_REALTIME, &(instance->_rtc_system_time));
+	instance->ScheduleNow(); // schedule work queue to publish PPS captured time
+
+	return PX4_OK;
+}
+
+int PPSCapture::task_spawn(int argc, char *argv[])
+{
+	PPSCapture *instance = new PPSCapture();
+
+	if (instance) {
+		_object.store(instance);
+		_task_id = task_id_is_work_queue;
+
+		if (instance->init()) {
+			return PX4_OK;
+		}
+
+	} else {
+		PX4_ERR("alloc failed");
+	}
+
+	delete instance;
+	_object.store(nullptr);
+	_task_id = -1;
+
+	return PX4_ERROR;
+}
+
+int PPSCapture::custom_command(int argc, char *argv[])
+{
+	return print_usage("unknown command");
+}
+
+int PPSCapture::print_usage(const char *reason)
+{
+	if (reason) {
+		PX4_WARN("%s\n", reason);
+	}
+
+	PRINT_MODULE_DESCRIPTION(
+		R"DESCR_STR(
+### Description
+This implements capturing PPS information from the GNSS module and calculates the drift between PPS and Real-time clock.
+
+)DESCR_STR");
+
+	PRINT_MODULE_USAGE_NAME("pps_capture", "driver");
+	PRINT_MODULE_USAGE_COMMAND("start");
+	PRINT_MODULE_USAGE_DEFAULT_COMMANDS();
+
+	return 0;
+}
+
+void PPSCapture::stop()
+{
+	exit_and_cleanup();
+}
+
+extern "C" __EXPORT int pps_capture_main(int argc, char *argv[])
+{
+	if (!strcmp(argv[1], "stop")) {
+		PPSCapture::stop();
+	}
+
+	return PPSCapture::main(argc, argv);
+}

src/drivers/pps_capture/PPSCapture.hpp

@@ -0,0 +1,77 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2021 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#pragma once
+
+#include <drivers/drv_hrt.h>
+#include <px4_arch/micro_hal.h>
+#include <px4_platform_common/module.h>
+#include <px4_platform_common/px4_work_queue/ScheduledWorkItem.hpp>
+#include <uORB/Publication.hpp>
+#include <uORB/topics/pps_capture.h>
+
+using namespace time_literals;
+
+class PPSCapture : public ModuleBase<PPSCapture>, public px4::ScheduledWorkItem
+{
+public:
+	PPSCapture();
+	virtual ~PPSCapture();
+
+	/** @see ModuleBase */
+	static int task_spawn(int argc, char *argv[]);
+
+	/** @see ModuleBase */
+	static int custom_command(int argc, char *argv[]);
+
+	/** @see ModuleBase */
+	static int print_usage(const char *reason = nullptr);
+
+	bool init();
+
+	static int gpio_interrupt_callback(int irq, void *context, void *arg);
+
+	/** PPSCapture is an interrupt-driven task and needs to be manually stopped */
+	static void stop();
+
+private:
+	void Run() override;
+
+	uORB::Publication<pps_capture_s>	_pps_capture_pub{ORB_ID(pps_capture)};
+
+	static constexpr unsigned USEC_IN_1_SEC{1000000}; // microseconds in 1 second
+	static constexpr unsigned MAX_POSITIVE_DRIFT{USEC_IN_1_SEC / 2}; // microseconds
+
+	timespec _rtc_system_time{0};
+
+};