Added simple, but complete code example

apps/examples/px4_simple_app/Makefile

@@ -0,0 +1,42 @@
+############################################################################
+#
+#   Copyright (C) 2012 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.
+#
+############################################################################
+
+#
+# Basic example application
+#
+
+APPNAME		 = px4_simple_app
+PRIORITY	 = SCHED_PRIORITY_DEFAULT
+STACKSIZE	 = 2048
+
+include $(APPDIR)/mk/app.mk

apps/examples/px4_simple_app/px4_simple_app.c

@@ -0,0 +1,115 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Author: @author Example User <mail@example.com>
+ *
+ * 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 px4_simple_app.c
+ * Minimal application example for PX4 autopilot
+ */
+
+#include <nuttx/config.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <poll.h>
+
+#include <uORB/uORB.h>
+#include <uORB/topics/sensor_combined.h>
+#include <uORB/topics/vehicle_attitude.h>
+
+__EXPORT int px4_simple_app_main(int argc, char *argv[]);
+
+int px4_simple_app_main(int argc, char *argv[])
+{
+	printf("Hello Sky!\n");
+
+	/* subscribe to sensor_combined topic */
+	int sensor_sub_fd = orb_subscribe(ORB_ID(sensor_combined));
+	orb_set_interval(sensor_sub_fd, 1000);
+
+	/* advertise attitude topic */
+	struct vehicle_attitude_s att;
+	memset(&att, 0, sizeof(att));
+	int att_pub_fd = orb_advertise(ORB_ID(vehicle_attitude), &att);
+
+	/* one could wait for multiple topics with this technique, just using one here */
+	struct pollfd fds[] = {
+		{ .fd = sensor_sub_fd,   .events = POLLIN },
+		/* there could be more file descriptors here, in the form like:
+		 * { .fd = other_sub_fd,   .events = POLLIN },
+		 */
+	};
+
+	int error_counter = 0;
+
+	while (true) {
+		/* wait for sensor update of 1 file descriptor for 1000 ms (1 second) */
+		int poll_ret = poll(fds, 1, 1000);
+	 
+		/* handle the poll result */
+		if (poll_ret == 0) {
+			/* this means none of our providers is giving us data */
+			printf("[px4_simple_app] Got no data within a second\n");
+		} else if (poll_ret < 0) {
+			/* this is seriously bad - should be an emergency */
+			if (error_counter < 10 || error_counter % 50 == 0) {
+				/* use a counter to prevent flooding (and slowing us down) */
+				printf("[px4_simple_app] ERROR return value from poll(): %d\n"
+					, poll_ret);
+			}
+			error_counter++;
+		} else {
+	 
+			if (fds[0].revents & POLLIN) {
+				/* obtained data for the first file descriptor */
+				struct sensor_combined_s raw;
+				/* copy sensors raw data into local buffer */
+				orb_copy(ORB_ID(sensor_combined), sensor_sub_fd, &raw);
+				printf("[px4_simple_app] Accelerometer:\t%8.4f\t%8.4f\t%8.4f\n",
+					(double)raw.accelerometer_m_s2[0],
+					(double)raw.accelerometer_m_s2[1],
+					(double)raw.accelerometer_m_s2[2]);
+
+				/* set att and publish this information for other apps */
+				att.roll = raw.accelerometer_m_s2[0];
+				att.pitch = raw.accelerometer_m_s2[1];
+				att.yaw = raw.accelerometer_m_s2[2];
+				orb_publish(ORB_ID(vehicle_attitude), att_pub_fd, &att);
+			}
+			/* there could be more file descriptors here, in the form like:
+			 * if (fds[1..n].revents & POLLIN) {}
+			 */
+		}
+	}
+
+	return 0;
+}

apps/sensors/sensors.c

@@ -112,6 +112,7 @@ static int fd_barometer = -1;
 static int fd_adc = -1;
 
 static bool thread_should_exit = false;
+static bool thread_running = false;
 static int sensors_task;
 
 /* Private functions declared static */
@@ -136,6 +137,11 @@ static int sensor_pub;
  */
 __EXPORT int sensors_main(int argc, char *argv[]);
 
+/**
+ * Print the usage
+ */
+static void usage(const char *reason);
+
 /**
  * Initialize all sensor drivers.
  *
@@ -425,6 +431,8 @@ int sensors_thread_main(int argc, char *argv[])
 	/* Enable high resolution timer callback to unblock main thread, run after 2 ms */
 	hrt_call_every(&sensors_hrt_call, 2000, SENSOR_INTERVAL_MICROSEC, &sensors_timer_loop, NULL);
 
+	thread_running = true;
+
 	while (1) {
 		pthread_mutex_lock(&sensors_read_ready_mutex);
 
@@ -909,6 +917,8 @@ int sensors_thread_main(int argc, char *argv[])
 
 #endif
 		}
+
+		if (thread_should_exit) break;
 	}
 
 	/* Never really getting here */
@@ -922,39 +932,52 @@ int sensors_thread_main(int argc, char *argv[])
 
 	printf("[sensors] exiting.\n");
 
+	thread_running = false;
+
 	return ret;
 }
 
-/**
- * Print the usage
- */
-static void usage(const char *reason);
-
 static void
 usage(const char *reason)
 {
 	if (reason)
 		fprintf(stderr, "%s\n", reason);
-	fprintf(stderr, "usage: sensors {start|stop}\n");
+	fprintf(stderr, "usage: sensors {start|stop|status}\n");
 	exit(1);
 }
 
 int sensors_main(int argc, char *argv[])
 {
-	int	ch;
-
 	if (argc < 1)
 		usage("missing command");
 
 	if (!strcmp(argv[1], "start")) {
 
-		thread_should_exit = false;
-		sensors_task = task_create("sensors", SCHED_PRIORITY_MAX - 5, 4096, sensors_thread_main, NULL);
+		if (thread_running) {
+			printf("sensors app already running\n");
+		} else {
+			thread_should_exit = false;
+			sensors_task = task_create("sensors", SCHED_PRIORITY_MAX - 5, 4096, sensors_thread_main, (argv) ? (const char **)&argv[2] : (const char **)NULL);
+		}
 		exit(0);
 	}
 
 	if (!strcmp(argv[1], "stop")) {
-		thread_should_exit = true;
+		if (!thread_running) {
+			printf("sensors app not started\n");
+		} else {
+			printf("stopping sensors app");
+			thread_should_exit = true;
+		}
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (thread_running) {
+			printf("\tsensors app is running\n");
+		} else {
+			printf("\tsensors app not started\n");
+		}
 		exit(0);
 	}
 

apps/uORB/uORB.cpp

@@ -728,7 +728,8 @@ uorb_main(int argc, char *argv[])
 
 		if (g_dev != nullptr) {
 			fprintf(stderr, "[uorb] already loaded\n");
-			return -EBUSY;
+			/* user wanted to start uorb, its already running, no error */
+			return 0;
 		}
 
 		/* create the driver */
@@ -759,10 +760,10 @@ uorb_main(int argc, char *argv[])
 	/*
 	 * Print driver information.
 	 */
-	if (!strcmp(argv[1], "info"))
+	if (!strcmp(argv[1], "status"))
 		return info();
 
-	fprintf(stderr, "unrecognised command, try 'start', 'test' or 'info'\n");
+	fprintf(stderr, "unrecognised command, try 'start', 'test' or 'status'\n");
 	return -EINVAL;
 }
 

nuttx/configs/px4fmu/nsh/appconfig

@@ -52,6 +52,10 @@ CONFIGURED_APPS += systemcmds/boardinfo
 CONFIGURED_APPS += systemcmds/mixer
 #CONFIGURED_APPS += systemcmds/calibration
 
+# Tutorial code from
+# https://pixhawk.ethz.ch/px4/dev/hello_sky
+# CONFIGURED_APPS += examples/px4_simple_app
+
 CONFIGURED_APPS += uORB
 
 ifeq ($(CONFIG_MAVLINK),y)