Add in missing files.

src/drivers/hott/comms.c

+/****************************************************************************
+ *
+ *   Copyright (c) 2013 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 comms.c
+ * @author Simon Wilks <sjwilks@gmail.com>
+ *
+ */
+
+#include "comms.h"
+
+#include <fcntl.h>
+#include <nuttx/config.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <systemlib/err.h>
+#include <systemlib/systemlib.h>
+
+int
+open_uart(const char *device, struct termios *uart_config_original)
+{
+	/* baud rate */
+	static const speed_t speed = B19200;
+
+	/* open uart */
+	const int uart = open(device, O_RDWR | O_NOCTTY);
+
+	if (uart < 0) {
+		err(1, "Error opening port: %s", device);
+	}
+	
+	/* Back up the original uart configuration to restore it after exit */	
+	int termios_state;
+	if ((termios_state = tcgetattr(uart, uart_config_original)) < 0) {
+		close(uart);
+		err(1, "Error getting baudrate / termios config for %s: %d", device, termios_state);
+	}
+
+	/* Fill the struct for the new configuration */
+	struct termios uart_config;
+	tcgetattr(uart, &uart_config);
+
+	/* Clear ONLCR flag (which appends a CR for every LF) */
+	uart_config.c_oflag &= ~ONLCR;
+
+	/* Set baud rate */
+	if (cfsetispeed(&uart_config, speed) < 0 || cfsetospeed(&uart_config, speed) < 0) {
+		close(uart);
+		err(1, "Error setting baudrate / termios config for %s: %d (cfsetispeed, cfsetospeed)",
+			 device, termios_state);
+	}
+
+	if ((termios_state = tcsetattr(uart, TCSANOW, &uart_config)) < 0) {
+		close(uart);
+		err(1, "Error setting baudrate / termios config for %s (tcsetattr)", device);
+	}
+
+	/* Activate single wire mode */
+	ioctl(uart, TIOCSSINGLEWIRE, SER_SINGLEWIRE_ENABLED);
+
+	return uart;
+}
+
+
+
+
+
+
+
+
+
+

src/drivers/hott/comms.h

+/****************************************************************************
+ *
+ *   Copyright (c) 2013 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 comms.h
+ * @author Simon Wilks <sjwilks@gmail.com>
+ *
+ */
+
+
+#ifndef COMMS_H_
+#define COMMS_H
+
+#include <termios.h>
+
+int open_uart(const char *device, struct termios *uart_config_original);
+
+#endif /* COMMS_H_ */
+
+
+
+
+
+
+
+
+
+

src/drivers/hott/hott_sensors/hott_sensors.c

+/****************************************************************************
+ *
+ *   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+ *   Author: Simon Wilks <sjwilks@gmail.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 hott_sensors.c
+ * @author Simon Wilks <sjwilks@gmail.com>
+ *
+ * Graupner HoTT sensor driver implementation.
+ *
+ * Poll any sensors connected to the PX4 via the telemetry wire.
+ */
+
+#include <fcntl.h>
+#include <nuttx/config.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <systemlib/err.h>
+#include <systemlib/systemlib.h>
+
+#include "../comms.h"
+#include "../messages.h"
+
+static int thread_should_exit = false;		/**< Deamon exit flag */
+static int thread_running = false;		/**< Deamon status flag */
+static int deamon_task;				/**< Handle of deamon task / thread */
+static const char daemon_name[] = "hott_sensors";
+static const char commandline_usage[] = "usage: hott_sensor start|status|stop [-d <device>]";
+
+/**
+ * Deamon management function.
+ */
+__EXPORT int hott_sensors_main(int argc, char *argv[]);
+
+/**
+ * Mainloop of daemon.
+ */
+int hott_sensors_thread_main(int argc, char *argv[]);
+
+static int recv_data(int uart, uint8_t *buffer, size_t *size, uint8_t *id);
+static int send_poll(int uart, uint8_t *buffer, size_t size);
+
+int
+send_poll(int uart, uint8_t *buffer, size_t size)
+{
+	for (size_t i = 0; i < size; i++) {
+		write(uart, &buffer[i], sizeof(buffer[i]));
+
+		/* Sleep before sending the next byte. */
+		usleep(POST_WRITE_DELAY_IN_USECS);
+	}
+
+	/* A hack the reads out what was written so the next read from the receiver doesn't get it. */
+	/* TODO: Fix this!! */
+	uint8_t dummy[size];
+	read(uart, &dummy, size);
+
+	return OK;
+}
+
+int
+recv_data(int uart, uint8_t *buffer, size_t *size, uint8_t *id)
+{
+	usleep(5000);
+
+	static const int timeout_ms = 1000;
+	struct pollfd fds[] = { { .fd = uart, .events = POLLIN } };
+
+	
+	// XXX should this poll be inside the while loop???
+	if (poll(fds, 1, timeout_ms) > 0) {
+		int i = 0;
+		bool stop_byte_read = false;
+		while (true)  {
+			read(uart, &buffer[i], sizeof(buffer[i]));
+			//printf("[%d]: %d\n", i, buffer[i]);
+
+			if (stop_byte_read) {
+				// XXX process checksum
+				*size = ++i;
+				return OK;
+			}
+			// XXX can some other field not have the STOP BYTE value?
+			if (buffer[i] == STOP_BYTE) {
+				*id = buffer[1];
+				stop_byte_read = true;
+			}
+			i++;
+		}
+	}
+	return ERROR;
+}
+
+int
+hott_sensors_thread_main(int argc, char *argv[])
+{
+	warnx("starting");
+
+	thread_running = true;
+
+	const char *device = "/dev/ttyS2";		/**< Default telemetry port: USART5 */
+
+	/* read commandline arguments */
+	for (int i = 0; i < argc && argv[i]; i++) {
+		if (strcmp(argv[i], "-d") == 0 || strcmp(argv[i], "--device") == 0) { //device set
+			if (argc > i + 1) {
+				device = argv[i + 1];
+
+			} else {
+				thread_running = false;
+				errx(1, "missing parameter to -d\n%s", commandline_usage);
+			}
+		}
+	}
+
+	/* enable UART, writes potentially an empty buffer, but multiplexing is disabled */
+	struct termios uart_config_original;
+	const int uart = open_uart(device, &uart_config_original);
+
+	if (uart < 0) {
+		errx(1, "Failed opening HoTT UART, exiting.");
+		thread_running = false;
+	}
+
+	uint8_t buffer[MESSAGE_BUFFER_SIZE];
+	size_t size = 0;
+	uint8_t id = 0;
+	bool connected = true;
+	while (!thread_should_exit) {
+		// Currently we only support a General Air Module sensor.
+		build_gam_request(&buffer, &size);
+		send_poll(uart, buffer, size);
+		recv_data(uart, &buffer, &size, &id);
+
+		// Determine which moduel sent it and process accordingly.
+		if (id == GAM_SENSOR_ID) {
+			//warnx("extract");
+			extract_gam_message(buffer);
+		} else {
+			warnx("Unknown sensor ID received: %d", id);
+		}	
+	}
+
+	warnx("exiting");
+
+	close(uart);
+
+	thread_running = false;
+
+	return 0;
+}
+
+/**
+ * Process command line arguments and start the daemon.
+ */
+int
+hott_sensors_main(int argc, char *argv[])
+{
+	if (argc < 1) {
+		errx(1, "missing command\n%s", commandline_usage);
+	}
+
+	if (!strcmp(argv[1], "start")) {
+
+		if (thread_running) {
+			warnx("deamon already running");
+			exit(0);
+		}
+
+		thread_should_exit = false;
+		deamon_task = task_spawn(daemon_name,
+					 SCHED_DEFAULT,
+					 SCHED_PRIORITY_MAX - 40,
+					 2048,
+					 hott_sensors_thread_main,
+					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "stop")) {
+		thread_should_exit = true;
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (thread_running) {
+			warnx("daemon is running");
+
+		} else {
+			warnx("daemon not started");
+		}
+
+		exit(0);
+	}
+
+	errx(1, "unrecognized command\n%s", commandline_usage);
+}

src/drivers/hott/hott_sensors/module.mk

+############################################################################
+#
+#   Copyright (c) 2012, 2013 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.
+#
+############################################################################
+
+#
+# Graupner HoTT Sensors application.
+#
+
+MODULE_COMMAND	= hott_sensors
+
+SRCS		= hott_sensors.c \
+		  ../messages.c \
+		  ../comms.c

src/drivers/hott/hott_telemetry/hott_telemetry.c

+/****************************************************************************
+ *
+ *   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+ *   Author: Simon Wilks <sjwilks@gmail.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 hott_telemetry_main.c
+ * @author Simon Wilks <sjwilks@gmail.com>
+ *
+ * Graupner HoTT Telemetry implementation.
+ *
+ * The HoTT receiver polls each device at a regular interval at which point
+ * a data packet can be returned if necessary.
+ *
+ */
+
+#include <fcntl.h>
+#include <nuttx/config.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <systemlib/err.h>
+#include <systemlib/systemlib.h>
+
+#include "../comms.h"
+#include "../messages.h"
+
+static int thread_should_exit = false;		/**< Deamon exit flag */
+static int thread_running = false;		/**< Deamon status flag */
+static int deamon_task;				/**< Handle of deamon task / thread */
+static const char daemon_name[] = "hott_telemetry";
+static const char commandline_usage[] = "usage: hott_telemetry start|status|stop [-d <device>]";
+
+/**
+ * Deamon management function.
+ */
+__EXPORT int hott_telemetry_main(int argc, char *argv[]);
+
+/**
+ * Mainloop of daemon.
+ */
+int hott_telemetry_thread_main(int argc, char *argv[]);
+
+static int recv_req_id(int uart, uint8_t *id);
+static int send_data(int uart, uint8_t *buffer, size_t size);
+
+int
+recv_req_id(int uart, uint8_t *id)
+{
+	static const int timeout_ms = 1000;  // TODO make it a define
+	struct pollfd fds[] = { { .fd = uart, .events = POLLIN } };
+
+	uint8_t mode;
+
+	if (poll(fds, 1, timeout_ms) > 0) {
+		/* Get the mode: binary or text  */
+		read(uart, &mode, sizeof(mode));
+
+		/* if we have a binary mode request */
+		if (mode != BINARY_MODE_REQUEST_ID) {
+			return ERROR;
+		}
+
+		/* Read the device ID being polled */
+		read(uart, id, sizeof(*id));
+	} else {
+		warnx("UART timeout on TX/RX port");
+		return ERROR;
+	}
+
+	return OK;
+}
+
+int
+recv_data(int uart, uint8_t *buffer, size_t *size, uint8_t *id)
+{
+	usleep(5000);
+
+	static const int timeout_ms = 1000;
+	struct pollfd fds[] = { { .fd = uart, .events = POLLIN } };
+
+	
+	// XXX should this poll be inside the while loop???
+	if (poll(fds, 1, timeout_ms) > 0) {
+		int i = 0;
+		bool stop_byte_read = false;
+		while (true)  {
+			read(uart, &buffer[i], sizeof(buffer[i]));
+			//printf("[%d]: %d\n", i, buffer[i]);
+
+			if (stop_byte_read) {
+				// process checksum
+				*size = ++i;
+				return OK;
+			}
+			// XXX can some other field not have the STOP BYTE value?
+			if (buffer[i] == STOP_BYTE) {
+				*id = buffer[1];
+				stop_byte_read = true;
+			}
+			i++;
+		}
+	}
+	return ERROR;
+}
+
+int
+send_data(int uart, uint8_t *buffer, size_t size)
+{
+	usleep(POST_READ_DELAY_IN_USECS);
+
+	uint16_t checksum = 0;
+	for (size_t i = 0; i < size; i++) {
+		if (i == size - 1) {
+			/* Set the checksum: the first uint8_t is taken as the checksum. */
+			buffer[i] = checksum & 0xff;
+
+		} else {
+			checksum += buffer[i];
+		}
+
+		write(uart, &buffer[i], sizeof(buffer[i]));
+
+		/* Sleep before sending the next byte. */
+		usleep(POST_WRITE_DELAY_IN_USECS);
+	}
+
+	/* A hack the reads out what was written so the next read from the receiver doesn't get it. */
+	/* TODO: Fix this!! */
+	uint8_t dummy[size];
+	read(uart, &dummy, size);
+
+	return OK;
+}
+
+int
+hott_telemetry_thread_main(int argc, char *argv[])
+{
+	warnx("starting");
+
+	thread_running = true;
+
+	const char *device = "/dev/ttyS1";		/**< Default telemetry port: USART2 */
+
+	/* read commandline arguments */
+	for (int i = 0; i < argc && argv[i]; i++) {
+		if (strcmp(argv[i], "-d") == 0 || strcmp(argv[i], "--device") == 0) { //device set
+			if (argc > i + 1) {
+				device = argv[i + 1];
+
+			} else {
+				thread_running = false;
+				errx(1, "missing parameter to -d\n%s", commandline_usage);
+			}
+		}
+	}
+
+	/* enable UART, writes potentially an empty buffer, but multiplexing is disabled */
+	struct termios uart_config_original;
+	const int uart = open_uart(device, &uart_config_original);
+
+	if (uart < 0) {
+		errx(1, "Failed opening HoTT UART, exiting.");
+		thread_running = false;
+	}
+
+	messages_init();
+
+	uint8_t buffer[MESSAGE_BUFFER_SIZE];
+	size_t size = 0;
+	uint8_t id = 0;
+	bool connected = true;
+	while (!thread_should_exit) {
+		// Listen for and serve poll from the receiver.
+		if (recv_req_id(uart, &id) == OK) {
+			if (!connected) {
+				connected = true;
+				warnx("OK");
+			}
+
+			switch (id) {
+			case EAM_SENSOR_ID:
+				build_eam_response(buffer, &size);
+				break;
+
+			case GPS_SENSOR_ID:
+				build_gps_response(buffer, &size);
+				break;
+
+			default:
+				continue;	// Not a module we support.
+			}
+
+			send_data(uart, buffer, size);
+		} else {
+			connected = false;
+			warnx("syncing");
+		}
+	}
+
+	warnx("exiting");
+
+	close(uart);
+
+	thread_running = false;
+
+	return 0;
+}
+
+/**
+ * Process command line arguments and start the daemon.
+ */
+int
+hott_telemetry_main(int argc, char *argv[])
+{
+	if (argc < 1) {
+		errx(1, "missing command\n%s", commandline_usage);
+	}
+
+	if (!strcmp(argv[1], "start")) {
+
+		if (thread_running) {
+			warnx("deamon already running");
+			exit(0);
+		}
+
+		thread_should_exit = false;
+		deamon_task = task_spawn(daemon_name,
+					 SCHED_DEFAULT,
+					 SCHED_PRIORITY_MAX - 40,
+					 2048,
+					 hott_telemetry_thread_main,
+					 (argv) ? (const char **)&argv[2] : (const char **)NULL);
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "stop")) {
+		thread_should_exit = true;
+		exit(0);
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (thread_running) {
+			warnx("daemon is running");
+
+		} else {
+			warnx("daemon not started");
+		}
+
+		exit(0);
+	}
+
+	errx(1, "unrecognized command\n%s", commandline_usage);
+}

src/drivers/hott/hott_telemetry/module.mk

+############################################################################
+#
+#   Copyright (c) 2012, 2013 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.
+#
+############################################################################
+
+#
+# Graupner HoTT Telemetry applications.
+#
+
+MODULE_COMMAND	= hott_telemetry
+
+SRCS		= hott_telemetry.c \
+		  ../messages.c \
+		  ../comms.c

src/drivers/hott/messages.c

+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Author: @author Simon Wilks <sjwilks@gmail.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 messages.c
+ *
+ */
+
+#include "messages.h"
+
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+#include <systemlib/geo/geo.h>
+#include <unistd.h>
+#include <uORB/topics/airspeed.h>
+#include <uORB/topics/battery_status.h>
+#include <uORB/topics/home_position.h>
+#include <uORB/topics/sensor_combined.h>
+#include <uORB/topics/vehicle_gps_position.h>
+
+/* The board is very roughly 5 deg warmer than the surrounding air */
+#define BOARD_TEMP_OFFSET_DEG 5
+
+static int battery_sub = -1;
+static int gps_sub = -1;
+static int home_sub = -1;
+static int sensor_sub = -1;
+static int airspeed_sub = -1;
+
+static bool home_position_set = false;
+static double home_lat = 0.0d;
+static double home_lon = 0.0d;
+
+void 
+messages_init(void)
+{
+	battery_sub = orb_subscribe(ORB_ID(battery_status));
+	gps_sub = orb_subscribe(ORB_ID(vehicle_gps_position));
+	home_sub = orb_subscribe(ORB_ID(home_position));
+	sensor_sub = orb_subscribe(ORB_ID(sensor_combined));
+	airspeed_sub = orb_subscribe(ORB_ID(airspeed));
+}
+
+void
+build_gam_request(uint8_t *buffer, size_t *size)
+{
+	struct gam_module_poll_msg msg;
+	*size = sizeof(msg);
+	memset(&msg, 0, *size);
+
+	msg.mode = BINARY_MODE_REQUEST_ID;
+	msg.id = GAM_SENSOR_ID;
+
+	memcpy(buffer, &msg, *size);
+}
+
+void
+extract_gam_message(const uint8_t *buffer)
+{
+	struct gam_module_msg msg;
+	size_t size = sizeof(msg);
+	memset(&msg, 0, size);
+	memcpy(&msg, buffer, size);
+
+	// Publish it.
+	uint16_t rpm = ((msg.rpm_H << 8) | (msg.rpm_L & 0xff)) * 10;
+	uint8_t temp = msg.temperature2 + 20;
+	float current = ((msg.current_H << 8) | (msg.current_L & 0xff)) * 0.1f;
+	printf("RPM: %d TEMP: %d A: %2.1f\n", rpm, temp, current);
+}
+
+void 
+build_eam_response(uint8_t *buffer, size_t *size)
+{
+	/* get a local copy of the current sensor values */
+	struct sensor_combined_s raw;
+	memset(&raw, 0, sizeof(raw));
+	orb_copy(ORB_ID(sensor_combined), sensor_sub, &raw);
+
+	/* get a local copy of the battery data */
+	struct battery_status_s battery;
+	memset(&battery, 0, sizeof(battery));
+	orb_copy(ORB_ID(battery_status), battery_sub, &battery);
+
+	struct eam_module_msg msg;
+	*size = sizeof(msg);
+	memset(&msg, 0, *size);
+
+	msg.start = START_BYTE;
+	msg.eam_sensor_id = EAM_SENSOR_ID;
+	msg.sensor_text_id = EAM_SENSOR_TEXT_ID;
+	
+	msg.temperature1 = (uint8_t)(raw.baro_temp_celcius - 20);
+	msg.temperature2 = msg.temperature1 - BOARD_TEMP_OFFSET_DEG;
+
+	msg.main_voltage_L = (uint8_t)(battery.voltage_v * 10);
+
+	uint16_t alt = (uint16_t)(raw.baro_alt_meter + 500);
+	msg.altitude_L = (uint8_t)alt & 0xff;
+	msg.altitude_H = (uint8_t)(alt >> 8) & 0xff;
+
+	/* get a local copy of the airspeed data */
+	struct airspeed_s airspeed;
+	memset(&airspeed, 0, sizeof(airspeed));
+	orb_copy(ORB_ID(airspeed), airspeed_sub, &airspeed);
+
+	uint16_t speed = (uint16_t)(airspeed.indicated_airspeed_m_s);
+	msg.speed_L = (uint8_t)speed & 0xff;
+	msg.speed_H = (uint8_t)(speed >> 8) & 0xff;
+
+	msg.stop = STOP_BYTE;
+	memcpy(buffer, &msg, *size);
+}
+
+void 
+build_gps_response(uint8_t *buffer, size_t *size)
+{
+	/* get a local copy of the current sensor values */
+	struct sensor_combined_s raw;
+	memset(&raw, 0, sizeof(raw));
+	orb_copy(ORB_ID(sensor_combined), sensor_sub, &raw);
+
+ 	/* get a local copy of the battery data */
+	struct vehicle_gps_position_s gps;
+	memset(&gps, 0, sizeof(gps));
+	orb_copy(ORB_ID(vehicle_gps_position), gps_sub, &gps);
+
+	struct gps_module_msg msg = { 0 };
+	*size = sizeof(msg);
+	memset(&msg, 0, *size);
+
+	msg.start = START_BYTE;
+	msg.sensor_id = GPS_SENSOR_ID;
+	msg.sensor_text_id = GPS_SENSOR_TEXT_ID;
+
+	msg.gps_num_sat = gps.satellites_visible;
+
+	/* The GPS fix type: 0 = none, 2 = 2D, 3 = 3D */
+	msg.gps_fix_char = (uint8_t)(gps.fix_type + 48);
+	msg.gps_fix = (uint8_t)(gps.fix_type + 48);
+
+	/* No point collecting more data if we don't have a 3D fix yet */
+	if (gps.fix_type > 2) {
+		/* Current flight direction */
+		msg.flight_direction = (uint8_t)(gps.cog_rad * M_RAD_TO_DEG_F);
+
+		/* GPS speed */
+		uint16_t speed = (uint16_t)(gps.vel_m_s * 3.6);
+		msg.gps_speed_L = (uint8_t)speed & 0xff;
+		msg.gps_speed_H = (uint8_t)(speed >> 8) & 0xff;
+		
+		/* Get latitude in degrees, minutes and seconds */
+		double lat = ((double)(gps.lat))*1e-7d;
+
+		/* Set the N or S specifier */		
+		msg.latitude_ns = 0;
+		if (lat < 0) {
+			msg.latitude_ns = 1;
+			lat = abs(lat);
+		}
+
+		int deg;
+		int min;
+		int sec;
+		convert_to_degrees_minutes_seconds(lat, &deg, &min, &sec);
+
+		uint16_t lat_min = (uint16_t)(deg * 100 + min);
+		msg.latitude_min_L = (uint8_t)lat_min & 0xff;
+		msg.latitude_min_H = (uint8_t)(lat_min >> 8) & 0xff;
+		uint16_t lat_sec = (uint16_t)(sec);
+		msg.latitude_sec_L = (uint8_t)lat_sec & 0xff;
+		msg.latitude_sec_H = (uint8_t)(lat_sec >> 8) & 0xff;
+
+		/* Get longitude in degrees, minutes and seconds */
+		double lon = ((double)(gps.lon))*1e-7d;
+
+		/* Set the E or W specifier */
+		msg.longitude_ew = 0;
+		if (lon < 0) {
+			msg.longitude_ew = 1;
+			lon = abs(lon);
+		}
+
+		convert_to_degrees_minutes_seconds(lon, &deg, &min, &sec);
+		
+		uint16_t lon_min = (uint16_t)(deg * 100 + min);
+		msg.longitude_min_L = (uint8_t)lon_min & 0xff;
+		msg.longitude_min_H = (uint8_t)(lon_min >> 8) & 0xff;
+		uint16_t lon_sec = (uint16_t)(sec);
+		msg.longitude_sec_L = (uint8_t)lon_sec & 0xff;
+		msg.longitude_sec_H = (uint8_t)(lon_sec >> 8) & 0xff;
+		
+		/* Altitude */
+		uint16_t alt = (uint16_t)(gps.alt*1e-3 + 500.0f);
+		msg.altitude_L = (uint8_t)alt & 0xff;
+		msg.altitude_H = (uint8_t)(alt >> 8) & 0xff;
+
+		/* Get any (and probably only ever one) home_sub postion report */
+		bool updated;
+		orb_check(home_sub, &updated);
+		if (updated) {
+			/* get a local copy of the home position data */
+			struct home_position_s home;
+			memset(&home, 0, sizeof(home));
+			orb_copy(ORB_ID(home_position), home_sub, &home);
+
+			home_lat = ((double)(home.lat))*1e-7d;
+			home_lon = ((double)(home.lon))*1e-7d;
+			home_position_set = true;
+		}
+
+		/* Distance from home */
+		if (home_position_set) {
+			uint16_t dist = (uint16_t)get_distance_to_next_waypoint(home_lat, home_lon, lat, lon);
+
+			msg.distance_L = (uint8_t)dist & 0xff;
+			msg.distance_H = (uint8_t)(dist >> 8) & 0xff;
+
+			/* Direction back to home */
+			uint16_t bearing = (uint16_t)(get_bearing_to_next_waypoint(home_lat, home_lon, lat, lon) * M_RAD_TO_DEG_F);
+			msg.home_direction = (uint8_t)bearing >> 1;
+		}
+	}
+
+	msg.stop = STOP_BYTE;
+	memcpy(buffer, &msg, *size);
+}
+
+void
+convert_to_degrees_minutes_seconds(double val, int *deg, int *min, int *sec)
+{
+	*deg = (int)val;
+
+	double delta = val - *deg;
+	const double min_d = delta * 60.0d;
+	*min = (int)min_d;
+	delta = min_d - *min;
+	*sec = (int)(delta * 10000.0d);
+}

src/drivers/hott/messages.h

+/****************************************************************************
+ *
+ *   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+ *   Author: Simon Wilks <sjwilks@gmail.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 messages.h
+ * @author Simon Wilks <sjwilks@gmail.com>
+ *
+ * Graupner HoTT Telemetry message generation.
+ *
+ */
+#ifndef MESSAGES_H_
+#define MESSAGES_H
+
+#include <stdlib.h>
+
+/* The HoTT receiver demands a minimum 5ms period of silence after delivering its request.
+ * Note that the value specified here is lower than 5000 (5ms) as time is lost constucting
+ * the message after the read which takes some milliseconds.
+ */
+#define POST_READ_DELAY_IN_USECS	4000
+/* A pause of 3ms is required between each uint8_t sent back to the HoTT receiver. Much lower
+ * values can be used in practise though.
+ */
+#define POST_WRITE_DELAY_IN_USECS	2000
+
+// Protocol constants.
+#define BINARY_MODE_REQUEST_ID	0x80	// Binary mode request.
+#define START_BYTE		0x7c
+#define STOP_BYTE		0x7d
+#define TEMP_ZERO_CELSIUS	0x14
+
+/* The GAM Module poll message. */
+struct gam_module_poll_msg {
+	uint8_t mode;
+	uint8_t id;
+};
+
+/* Electric Air Module (EAM) constants. */
+#define EAM_SENSOR_ID			0x8e
+#define EAM_SENSOR_TEXT_ID		0xe0
+
+/* The Electric Air Module message. */
+struct eam_module_msg {
+	uint8_t start;			/**< Start byte   				*/
+	uint8_t eam_sensor_id;		/**< EAM sensor					*/
+	uint8_t warning;
+	uint8_t sensor_text_id;
+	uint8_t alarm_inverse1;
+	uint8_t alarm_inverse2;
+	uint8_t cell1_L;		/**< Lipo cell voltages. Not supported.	*/
+	uint8_t cell2_L;
+	uint8_t cell3_L;
+	uint8_t cell4_L;
+	uint8_t cell5_L;
+	uint8_t cell6_L;
+	uint8_t cell7_L;
+	uint8_t cell1_H;
+	uint8_t cell2_H;
+	uint8_t cell3_H;
+	uint8_t cell4_H;
+	uint8_t cell5_H;
+	uint8_t cell6_H;
+	uint8_t cell7_H;
+	uint8_t batt1_voltage_L;	/**< Battery 1 voltage, lower 8-bits in steps of 0.02V 	*/
+	uint8_t batt1_voltage_H;
+	uint8_t batt2_voltage_L;	/**< Battery 2 voltage, lower 8-bits in steps of 0.02V 	*/
+	uint8_t batt2_voltage_H;
+	uint8_t temperature1;		/**< Temperature sensor 1. 20 = 0 degrees */
+	uint8_t temperature2;
+	uint8_t altitude_L;		/**< Attitude (meters) lower 8-bits. 500 = 0 meters */
+	uint8_t altitude_H;
+	uint8_t current_L;		/**< Current (mAh) lower 8-bits in steps of 0.1V */
+	uint8_t current_H;
+	uint8_t main_voltage_L;		/**< Main power voltage lower 8-bits in steps of 0.1V */
+	uint8_t main_voltage_H;
+	uint8_t battery_capacity_L;	/**< Used battery capacity in steps of 10mAh */
+	uint8_t battery_capacity_H;
+	uint8_t climbrate_L;		/**< Climb rate in 0.01m/s. 0m/s = 30000 */
+	uint8_t climbrate_H;
+	uint8_t climbrate_3s;		/**< Climb rate in m/3sec. 0m/3sec = 120 */
+	uint8_t rpm_L;			/**< RPM Lower 8-bits In steps of 10 U/min */
+	uint8_t rpm_H;
+	uint8_t electric_min;		/**< Flight time in minutes. */
+	uint8_t electric_sec;		/**< Flight time in seconds. */
+	uint8_t speed_L;		/**< Airspeed in km/h in steps of 1 km/h */
+	uint8_t speed_H;
+	uint8_t stop;			/**< Stop byte */
+	uint8_t checksum;		/**< Lower 8-bits of all bytes summed. */
+};
+
+/** 
+ * The maximum buffer size required to store an Electric Air Module message.
+ */
+#define EAM_MESSAGE_BUFFER_SIZE sizeof(union { 	\
+    struct eam_module_msg eam; 			\
+})
+
+
+/* General Air Module (GAM) constants. */
+#define GAM_SENSOR_ID			0x8d
+#define GAM_SENSOR_TEXT_ID		0xd0
+
+struct gam_module_msg {
+        uint8_t start_byte;		// start byte constant value 0x7c
+        uint8_t gam_sensor_id;		// EAM sensort id. constat value 0x8d
+        uint8_t warning_beeps;		// 1=A 2=B ... 0x1a=Z  0 = no alarm
+        uint8_t sensor_id;		// constant value 0xd0
+        uint8_t alarm_invers1;		// alarm bitmask. Value is displayed inverted
+        uint8_t alarm_invers2;		// alarm bitmask. Value is displayed inverted                                                                
+        uint8_t cell1;			// cell 1 voltage lower value. 0.02V steps, 124=2.48V
+        uint8_t cell2;
+        uint8_t cell3;
+        uint8_t cell4;
+        uint8_t cell5;
+        uint8_t cell6;
+        uint8_t batt1_L;		// battery 1 voltage LSB value. 0.1V steps. 50 = 5.5V
+        uint8_t batt1_H;
+        uint8_t batt2_L;		// battery 2 voltage LSB value. 0.1V steps. 50 = 5.5V
+        uint8_t batt2_H;
+        uint8_t temperature1;		// temperature 1. offset of 20. a value of 20 = 0°C
+        uint8_t temperature2;		// temperature 2. offset of 20. a value of 20 = 0°C
+        uint8_t fuel_procent;		// Fuel capacity in %. Values 0--100
+					// graphical display ranges: 0-25% 50% 75% 100%
+        uint8_t fuel_ml_L;		// Fuel in ml scale. Full = 65535!
+        uint8_t fuel_ml_H;		//
+        uint8_t rpm_L;			// RPM in 10 RPM steps. 300 = 3000rpm
+        uint8_t rpm_H;			//
+        uint8_t altitude_L;		// altitude in meters. offset of 500, 500 = 0m
+        uint8_t altitude_H;		//
+        uint8_t climbrate_L;		// climb rate in 0.01m/s. Value of 30000 = 0.00 m/s
+        uint8_t climbrate_H;		//
+        uint8_t climbrate3s;		// climb rate in m/3sec. Value of 120 = 0m/3sec
+        uint8_t current_L;		// current in 0.1A steps
+        uint8_t current_H;		//
+        uint8_t main_voltage_L;		// Main power voltage using 0.1V steps
+        uint8_t main_voltage_H;		//
+        uint8_t batt_cap_L;		// used battery capacity in 10mAh steps
+        uint8_t batt_cap_H;		//
+        uint8_t speed_L;		// (air?) speed in km/h(?) we are using ground speed here per default
+        uint8_t speed_H;		//
+        uint8_t min_cell_volt;		// minimum cell voltage in 2mV steps. 124 = 2,48V
+        uint8_t min_cell_volt_num;	// number of the cell with the lowest voltage
+        uint8_t rpm2_L;			// RPM in 10 RPM steps. 300 = 3000rpm
+        uint8_t rpm2_H;			//
+        uint8_t general_error_number;	// Voice error == 12. TODO: more docu
+        uint8_t pressure;		// Pressure up to 16bar. 0,1bar scale. 20 = 2bar
+        uint8_t version;		// version number TODO: more info?
+        uint8_t stop;			// stop byte
+        uint8_t checksum;		// checksum
+};
+
+/** 
+ * The maximum buffer size required to store a General Air Module message.
+ */
+#define GAM_MESSAGE_BUFFER_SIZE sizeof(union { 	\
+    struct gam_module_msg gam; 			\
+})
+
+
+/* GPS sensor constants. */
+#define GPS_SENSOR_ID		0x8a
+#define GPS_SENSOR_TEXT_ID	0xa0
+
+/** 
+ * The GPS sensor message
+ * Struct based on: https://code.google.com/p/diy-hott-gps/downloads 
+ */
+struct gps_module_msg { 
+	uint8_t start;			/**< Start byte */
+	uint8_t sensor_id;		/**< GPS sensor ID*/
+	uint8_t warning;		/**< Byte 3: 0…= warning beeps */
+	uint8_t sensor_text_id;		/**< GPS Sensor text mode ID */
+	uint8_t alarm_inverse1;		/**< Byte 5: 01 inverse status */
+	uint8_t alarm_inverse2;		/**< Byte 6: 00 inverse status status 1 = no GPS Signal */
+	uint8_t flight_direction;	/**< Byte 7: 119 = Flightdir./dir. 1 = 2°; 0° (North), 9 0° (East), 180° (South), 270° (West) */
+	uint8_t gps_speed_L;		/**< Byte 8: 8 = /GPS speed low byte 8km/h */
+	uint8_t gps_speed_H;		/**< Byte 9: 0 = /GPS speed high byte */
+	  
+	uint8_t latitude_ns;		/**< Byte 10: 000 = N = 48°39’988 */
+	uint8_t latitude_min_L;		/**< Byte 11: 231 0xE7 = 0x12E7 = 4839 */
+	uint8_t latitude_min_H;		/**< Byte 12: 018 18 = 0x12 */
+	uint8_t latitude_sec_L;		/**< Byte 13: 171 220 = 0xDC = 0x03DC =0988 */
+	uint8_t latitude_sec_H;		/**< Byte 14: 016 3 = 0x03 */
+	 
+	uint8_t longitude_ew;		/**< Byte 15: 000  = E= 9° 25’9360 */
+	uint8_t longitude_min_L;	/**< Byte 16: 150 157 = 0x9D = 0x039D = 0925 */
+	uint8_t longitude_min_H;	/**< Byte 17: 003 3 = 0x03 */
+	uint8_t longitude_sec_L;	/**< Byte 18: 056 144 = 0x90 0x2490 = 9360*/
+	uint8_t longitude_sec_H;	/**< Byte 19: 004 36 = 0x24 */
+	  
+	uint8_t distance_L;			/**< Byte 20: 027 123 = /distance low byte 6 = 6 m */
+	uint8_t distance_H;			/**< Byte 21: 036 35 = /distance high byte */
+	uint8_t altitude_L;			/**< Byte 22: 243 244 = /Altitude low byte 500 = 0m */
+	uint8_t altitude_H;			/**< Byte 23: 001 1 = /Altitude high byte */
+	uint8_t resolution_L;		/**< Byte 24: 48 = Low Byte m/s resolution 0.01m 48 = 30000 = 0.00m/s (1=0.01m/s) */
+	uint8_t resolution_H;		/**< Byte 25: 117 = High Byte m/s resolution 0.01m */
+	uint8_t unknown1;			/**< Byte 26: 120 = 0m/3s */
+	uint8_t gps_num_sat;		/**< Byte 27: GPS.Satellites (number of satelites) (1 byte) */
+	uint8_t gps_fix_char;		/**< Byte 28: GPS.FixChar. (GPS fix character. display, if DGPS, 2D oder 3D) (1 byte) */
+	uint8_t home_direction;		/**< Byte 29: HomeDirection (direction from starting point to Model position) (1 byte) */
+	uint8_t angle_x_direction;	/**< Byte 30: angle x-direction (1 byte) */
+	uint8_t angle_y_direction;	/**< Byte 31: angle y-direction (1 byte) */
+	uint8_t angle_z_direction;	/**< Byte 32: angle z-direction (1 byte) */
+	uint8_t gyro_x_L;			/**< Byte 33: gyro x low byte (2 bytes) */
+	uint8_t gyro_x_H;			/**< Byte 34: gyro x high byte */
+	uint8_t gyro_y_L;			/**< Byte 35: gyro y low byte (2 bytes) */
+	uint8_t gyro_y_H;			/**< Byte 36: gyro y high byte */
+	uint8_t gyro_z_L;			/**< Byte 37: gyro z low byte (2 bytes) */
+	uint8_t gyro_z_H;			/**< Byte 38: gyro z high byte */
+	uint8_t vibration;			/**< Byte 39: vibration (1 bytes) */
+	uint8_t ascii4;				/**< Byte 40: 00 ASCII Free Character [4] */
+	uint8_t ascii5;				/**< Byte 41: 00 ASCII Free Character [5] */
+	uint8_t gps_fix;			/**< Byte 42: 00 ASCII Free Character [6], we use it for GPS FIX */
+	uint8_t version;			/**< Byte 43: 00 version number */
+	uint8_t stop;				/**< Byte 44: 0x7D Ende byte */
+	uint8_t checksum;			/**< Byte 45: Parity Byte */
+};
+
+/** 
+ * The maximum buffer size required to store a HoTT message.
+ */
+#define GPS_MESSAGE_BUFFER_SIZE sizeof(union { 	\
+    struct gps_module_msg gps; 			\
+})
+
+#define MESSAGE_BUFFER_SIZE GPS_MESSAGE_BUFFER_SIZE
+
+void messages_init(void);
+void build_gam_request(uint8_t *buffer, size_t *size);
+void extract_gam_message(const uint8_t *buffer);
+void build_eam_response(uint8_t *buffer, size_t *size);
+void build_gps_response(uint8_t *buffer, size_t *size);
+float _get_distance_to_next_waypoint(double lat_now, double lon_now, double lat_next, double lon_next);
+void convert_to_degrees_minutes_seconds(double lat, int *deg, int *min, int *sec);
+
+
+#endif /* MESSAGES_H_ */