Merge pull request #337 from sjwilks/hott-esc

Driver for the reading Graupner HoTT sensors (such as their ESC range) via the telemetry port

10 files changed, 650 insertions, 126 deletions

diff --git a/makefiles/config_px4fmu-v1_default.mk b/makefiles/config_px4fmu-v1_default.mk
index 213eb651b..74be1cd23 100644
--- a/makefiles/config_px4fmu-v1_default.mk
+++ b/makefiles/config_px4fmu-v1_default.mk
@@ -27,7 +27,8 @@ MODULES		+= drivers/ms5611
 MODULES		+= drivers/mb12xx
 MODULES		+= drivers/gps
 MODULES		+= drivers/hil
-MODULES		+= drivers/hott_telemetry
+MODULES		+= drivers/hott/hott_telemetry
+MODULES		+= drivers/hott/hott_sensors
 MODULES		+= drivers/blinkm
 MODULES		+= drivers/mkblctrl
 MODULES		+= drivers/md25
diff --git a/src/drivers/hott/comms.cpp b/src/drivers/hott/comms.cpp
new file mode 100644
index 000000000..cb8bbba37
--- /dev/null
+++ b/src/drivers/hott/comms.cpp
@@ -0,0 +1,92 @@
+/****************************************************************************
+ *
+ *   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 <stdio.h>
+#include <sys/ioctl.h>
+#include <systemlib/err.h>
+#include <termios.h>
+
+int
+open_uart(const char *device)
+{
+	/* 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;
+	struct termios uart_config_original;
+	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;
+}
diff --git a/src/drivers/hott/comms.h b/src/drivers/hott/comms.h
new file mode 100644
index 000000000..f5608122f
--- /dev/null
+++ b/src/drivers/hott/comms.h
@@ -0,0 +1,46 @@
+/****************************************************************************
+ *
+ *   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
+
+int open_uart(const char *device);
+
+#endif /* COMMS_H_ */
diff --git a/src/drivers/hott/hott_sensors/hott_sensors.cpp b/src/drivers/hott/hott_sensors/hott_sensors.cpp
new file mode 100644
index 000000000..e322c6349
--- /dev/null
+++ b/src/drivers/hott/hott_sensors/hott_sensors.cpp
@@ -0,0 +1,238 @@
+/****************************************************************************
+ *
+ *   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 <sys/ioctl.h>
+#include <unistd.h>
+#include <systemlib/err.h>
+#include <systemlib/systemlib.h>
+
+#include "../comms.h"
+#include "../messages.h"
+
+#define DEFAULT_UART "/dev/ttyS0";		/**< USART1 */
+
+/* Oddly, ERROR is not defined for C++ */
+#ifdef ERROR
+# undef ERROR
+#endif
+static const int ERROR = -1;
+
+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_sensors start|status|stop [-d <device>]";
+
+/**
+ * Deamon management function.
+ */
+extern "C" __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)
+{
+	static const int timeout_ms = 1000;
+	
+	struct pollfd fds;
+	fds.fd = uart;
+	fds.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]));
+
+			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 = DEFAULT_UART;
+
+	/* 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 */
+	const int uart = open_uart(device);
+	if (uart < 0) {
+		errx(1, "Failed opening HoTT UART, exiting.");
+		thread_running = false;
+	}
+
+	init_pub_messages();
+
+	uint8_t buffer[MAX_MESSAGE_BUFFER_SIZE];
+	size_t size = 0;
+	uint8_t id = 0;
+	while (!thread_should_exit) {
+		// Currently we only support a General Air Module sensor.
+		build_gam_request(&buffer[0], &size);
+		send_poll(uart, buffer, size);
+
+		// The sensor will need a little time before it starts sending.
+		usleep(5000);
+
+		recv_data(uart, &buffer[0], &size, &id);
+
+		// Determine which moduel sent it and process accordingly.
+		if (id == GAM_SENSOR_ID) {
+			publish_gam_message(buffer);
+		} else {
+			warnx("Unknown sensor ID: %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_cmd(daemon_name,
+					     SCHED_DEFAULT,
+					     SCHED_PRIORITY_MAX - 40,
+					     1024,
+					     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);
+}
diff --git a/src/drivers/hott/hott_sensors/module.mk b/src/drivers/hott/hott_sensors/module.mk
new file mode 100644
index 000000000..b5f5762ba
--- /dev/null
+++ b/src/drivers/hott/hott_sensors/module.mk
@@ -0,0 +1,42 @@
+############################################################################
+#
+#   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.cpp \
+		  ../messages.cpp \
+		  ../comms.cpp
diff --git a/src/drivers/hott_telemetry/hott_telemetry_main.c b/src/drivers/hott/hott_telemetry/hott_telemetry.cpp
index 4699ce5bf..042d9f816 100644
--- a/src/drivers/hott_telemetry/hott_telemetry_main.c
+++ b/src/drivers/hott/hott_telemetry/hott_telemetry.cpp
@@ -41,7 +41,6 @@
  * The HoTT receiver polls each device at a regular interval at which point
  * a data packet can be returned if necessary.
  *
- * TODO: Add support for at least the vario and GPS sensor data.
  */
 
 #include <fcntl.h>
@@ -50,13 +49,21 @@
 #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 "messages.h"
+#include "../comms.h"
+#include "../messages.h"
+
+#define DEFAULT_UART "/dev/ttyS0";		/**< USART1 */
+
+/* Oddly, ERROR is not defined for C++ */
+#ifdef ERROR
+# undef ERROR
+#endif
+static const int ERROR = -1;
 
 static int thread_should_exit = false;		/**< Deamon exit flag */
 static int thread_running = false;		/**< Deamon status flag */
@@ -67,7 +74,7 @@ static const char commandline_usage[] = "usage: hott_telemetry start|status|stop
 /**
  * Deamon management function.
  */
-__EXPORT int hott_telemetry_main(int argc, char *argv[]);
+extern "C" __EXPORT int hott_telemetry_main(int argc, char *argv[]);
 
 /**
  * Mainloop of daemon.
@@ -77,60 +84,18 @@ 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);
 
-static 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;
-}
-
 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;
+	
+	struct pollfd fds;
+	fds.fd = uart;
+	fds.events = POLLIN;
 
-	if (poll(fds, 1, timeout_ms) > 0) {
+	if (poll(&fds, 1, timeout_ms) > 0) {
 		/* Get the mode: binary or text  */
 		read(uart, &mode, sizeof(mode));
 
@@ -155,7 +120,6 @@ 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. */
@@ -186,7 +150,7 @@ hott_telemetry_thread_main(int argc, char *argv[])
 
 	thread_running = true;
 
-	const char *device = "/dev/ttyS1";		/**< Default telemetry port: USART2 */
+	const char *device = DEFAULT_UART;
 
 	/* read commandline arguments */
 	for (int i = 0; i < argc && argv[i]; i++) {
@@ -202,22 +166,20 @@ hott_telemetry_thread_main(int argc, char *argv[])
 	}
 
 	/* 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);
-
+	const int uart = open_uart(device);
 	if (uart < 0) {
 		errx(1, "Failed opening HoTT UART, exiting.");
 		thread_running = false;
 	}
 
-	messages_init();
+	init_sub_messages();
 
-	uint8_t buffer[MESSAGE_BUFFER_SIZE];
+	uint8_t buffer[MAX_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;
@@ -228,7 +190,9 @@ hott_telemetry_thread_main(int argc, char *argv[])
 			case EAM_SENSOR_ID:
 				build_eam_response(buffer, &size);
 				break;
-
+			case GAM_SENSOR_ID:
+				build_gam_response(buffer, &size);
+				break;
 			case GPS_SENSOR_ID:
 				build_gps_response(buffer, &size);
 				break;
@@ -254,7 +218,7 @@ hott_telemetry_thread_main(int argc, char *argv[])
 }
 
 /**
- * Process command line arguments and tart the daemon.
+ * Process command line arguments and start the daemon.
  */
 int
 hott_telemetry_main(int argc, char *argv[])
diff --git a/src/drivers/hott_telemetry/module.mk b/src/drivers/hott/hott_telemetry/module.mk
index def1d59e9..b19cbd14c 100644
--- a/src/drivers/hott_telemetry/module.mk
+++ b/src/drivers/hott/hott_telemetry/module.mk
@@ -32,10 +32,11 @@
 ############################################################################
 
 #
-# Graupner HoTT Telemetry application.
+# Graupner HoTT Telemetry applications.
 #
 
 MODULE_COMMAND	= hott_telemetry
 
-SRCS		= hott_telemetry_main.c \
-		  messages.c
+SRCS		= hott_telemetry.cpp \
+		  ../messages.cpp \
+		  ../comms.cpp
diff --git a/src/drivers/hott_telemetry/messages.c b/src/drivers/hott/messages.cpp
index 0ce56acef..57c256339 100644
--- a/src/drivers/hott_telemetry/messages.c
+++ b/src/drivers/hott/messages.cpp
@@ -46,6 +46,7 @@
 #include <unistd.h>
 #include <uORB/topics/airspeed.h>
 #include <uORB/topics/battery_status.h>
+#include <uORB/topics/esc_status.h>
 #include <uORB/topics/home_position.h>
 #include <uORB/topics/sensor_combined.h>
 #include <uORB/topics/vehicle_gps_position.h>
@@ -53,24 +54,75 @@
 /* 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 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 int _esc_sub = -1;
 
-static bool home_position_set = false;
-static double home_lat = 0.0d;
-static double home_lon = 0.0d;
+static orb_advert_t _esc_pub;
+struct esc_status_s _esc;
+
+static bool _home_position_set = false;
+static double _home_lat = 0.0d;
+static double _home_lon = 0.0d;
 
 void 
-messages_init(void)
+init_sub_messages(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));
+	_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));
+	_esc_sub = orb_subscribe(ORB_ID(esc_status));
+}
+
+void 
+init_pub_messages(void)
+{
+	memset(&_esc, 0, sizeof(_esc));
+	_esc_pub = orb_advertise(ORB_ID(esc_status), &_esc);
+}
+
+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
+publish_gam_message(const uint8_t *buffer)
+{
+	struct gam_module_msg msg;
+	size_t size = sizeof(msg);
+	memset(&msg, 0, size);
+	memcpy(&msg, buffer, size);
+
+	/* announce the esc if needed, just publish else */
+	if (_esc_pub > 0) {
+		orb_publish(ORB_ID(esc_status), _esc_pub, &_esc);
+	} else {
+		_esc_pub = orb_advertise(ORB_ID(esc_status), &_esc);
+	}
+
+	// Publish it.
+	_esc.esc_count = 1;
+	_esc.esc_connectiontype = ESC_CONNECTION_TYPE_PPM;
+
+	_esc.esc[0].esc_vendor = ESC_VENDOR_GRAUPNER_HOTT;
+	_esc.esc[0].esc_rpm = (uint16_t)((msg.rpm_H << 8) | (msg.rpm_L & 0xff)) * 10;
+	_esc.esc[0].esc_temperature = msg.temperature1 - 20; 
+	_esc.esc[0].esc_voltage = (uint16_t)((msg.main_voltage_H << 8) | (msg.main_voltage_L & 0xff));
+	_esc.esc[0].esc_current = (uint16_t)((msg.current_H << 8) | (msg.current_L & 0xff));
 }
 
 void 
@@ -79,12 +131,12 @@ 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);
+	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);
+	orb_copy(ORB_ID(battery_status), _battery_sub, &battery);
 
 	struct eam_module_msg msg;
 	*size = sizeof(msg);
@@ -92,7 +144,7 @@ build_eam_response(uint8_t *buffer, size_t *size)
 
 	msg.start = START_BYTE;
 	msg.eam_sensor_id = EAM_SENSOR_ID;
-	msg.sensor_id = EAM_SENSOR_TEXT_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;
@@ -106,12 +158,46 @@ build_eam_response(uint8_t *buffer, size_t *size)
 	/* 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);
+	orb_copy(ORB_ID(airspeed), _airspeed_sub, &airspeed);
 
 	uint16_t speed = (uint16_t)(airspeed.indicated_airspeed_m_s * 3.6f);
 	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_gam_response(uint8_t *buffer, size_t *size)
+{
+	/* get a local copy of the ESC Status values */
+	struct esc_status_s esc;
+	memset(&esc, 0, sizeof(esc));
+	orb_copy(ORB_ID(esc_status), _esc_sub, &esc);
+
+	struct gam_module_msg msg;
+	*size = sizeof(msg);
+	memset(&msg, 0, *size);
+
+	msg.start = START_BYTE;
+	msg.gam_sensor_id = GAM_SENSOR_ID;
+	msg.sensor_text_id = GAM_SENSOR_TEXT_ID;
+	
+	msg.temperature1 = (uint8_t)(esc.esc[0].esc_temperature + 20);
+	msg.temperature2 = 20;  // 0 deg. C.
+
+	uint16_t voltage = (uint16_t)(esc.esc[0].esc_voltage);
+	msg.main_voltage_L = (uint8_t)voltage & 0xff;
+	msg.main_voltage_H = (uint8_t)(voltage >> 8) & 0xff;
+
+	uint16_t current = (uint16_t)(esc.esc[0].esc_current);
+	msg.current_L = (uint8_t)current & 0xff;
+	msg.current_H = (uint8_t)(current >> 8) & 0xff;
+
+	uint16_t rpm = (uint16_t)(esc.esc[0].esc_rpm * 0.1f);
+	msg.rpm_L = (uint8_t)rpm & 0xff;
+	msg.rpm_H = (uint8_t)(rpm >> 8) & 0xff;
 
 	msg.stop = STOP_BYTE;
 	memcpy(buffer, &msg, *size);
@@ -123,14 +209,14 @@ 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);
+	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);
+	orb_copy(ORB_ID(vehicle_gps_position), _gps_sub, &gps);
 
-	struct gps_module_msg msg = { 0 };
+	struct gps_module_msg msg;
 	*size = sizeof(msg);
 	memset(&msg, 0, *size);
 
@@ -150,7 +236,7 @@ build_gps_response(uint8_t *buffer, size_t *size)
 		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);
+		uint16_t speed = (uint16_t)(gps.vel_m_s * 3.6f);
 		msg.gps_speed_L = (uint8_t)speed & 0xff;
 		msg.gps_speed_H = (uint8_t)(speed >> 8) & 0xff;
 		
@@ -196,33 +282,33 @@ build_gps_response(uint8_t *buffer, size_t *size)
 		msg.longitude_sec_H = (uint8_t)(lon_sec >> 8) & 0xff;
 		
 		/* Altitude */
-		uint16_t alt = (uint16_t)(gps.alt*1e-3 + 500.0f);
+		uint16_t alt = (uint16_t)(gps.alt*1e-3f + 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 */
+		/* Get any (and probably only ever one) _home_sub postion report */
 		bool updated;
-		orb_check(home_sub, &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);
+			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;
+			_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);
+		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);
+			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;
 		}
 	}
diff --git a/src/drivers/hott_telemetry/messages.h b/src/drivers/hott/messages.h
index e6d5cc723..451bee91c 100644
--- a/src/drivers/hott_telemetry/messages.h
+++ b/src/drivers/hott/messages.h
@@ -60,19 +60,25 @@
 #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 start;			/**< Start byte   				*/
 	uint8_t eam_sensor_id;		/**< EAM sensor					*/
 	uint8_t warning;
-	uint8_t sensor_id;			/**< Sensor ID, why different?	*/
+	uint8_t sensor_text_id;
 	uint8_t alarm_inverse1;
 	uint8_t alarm_inverse2;
-	uint8_t cell1_L;			/**< Lipo cell voltages. Not supported.	*/
+	uint8_t cell1_L;		/**< Lipo cell voltages. Not supported.	*/
 	uint8_t cell2_L;
 	uint8_t cell3_L;
 	uint8_t cell4_L;
@@ -92,9 +98,9 @@ struct eam_module_msg {
 	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_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_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;
@@ -103,35 +109,82 @@ struct eam_module_msg {
 	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_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_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. */
+	uint8_t stop;			/**< Stop byte */
+	uint8_t checksum;		/**< Lower 8-bits of all bytes summed. */
 };
 
-/** 
- * The maximum buffer size required to store a HoTT message.
- */
-#define 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;		// 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_text_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
+};
 
 /* GPS sensor constants. */
-#define GPS_SENSOR_ID		0x8A
-#define GPS_SENSOR_TEXT_ID	0xA0
+#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 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 */
@@ -179,15 +232,15 @@ struct gps_module_msg {
 	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; 				\
-})
+// The maximum size of a message.
+#define MAX_MESSAGE_BUFFER_SIZE 45
 
-void messages_init(void);
+void init_sub_messages(void);
+void init_pub_messages(void);
+void build_gam_request(uint8_t *buffer, size_t *size);
+void publish_gam_message(const uint8_t *buffer);
 void build_eam_response(uint8_t *buffer, size_t *size);
+void build_gam_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);
diff --git a/src/modules/uORB/topics/esc_status.h b/src/modules/uORB/topics/esc_status.h
index e67a39e1e..00cf59b28 100644
--- a/src/modules/uORB/topics/esc_status.h
+++ b/src/modules/uORB/topics/esc_status.h
@@ -63,7 +63,8 @@
 
 enum ESC_VENDOR {
 	ESC_VENDOR_GENERIC = 0,					/**< generic ESC */
-	ESC_VENDOR_MIKROKOPTER					/**< Mikrokopter */
+	ESC_VENDOR_MIKROKOPTER,					/**< Mikrokopter */
+	ESC_VENDOR_GRAUPNER_HOTT				/**< Graupner HoTT ESC */	
 };
 
 enum ESC_CONNECTION_TYPE {