Hardware on Paparazzi UAV Blog

New Paparazzi autopilot Chimera released

Mon, 20 Mar 2017 00:11:06 +0000

The ENAC UAV lab is proud to release its latest autopilot board. Named Chimera, it is based on the latest STM32F7 micro-controller and offers a large connectivity.

The design have been made with the ease of use and integration for end-users, especially researchers. With the usual features like IMU and barometer, the Chimera also carries a differential pressure sensor, a SD card slot, a XBee modem slot and a 5V power supply dedicated to external companion processor.

First flights of the hybrid vehicle Cyfoam with Chimera board

Sun, 12 Mar 2017 13:09:11 +0000

The Cyfoam is a hybrid vehicle developed at ENAC Drone Lab. The aircraft is a foam, with a 3D printed fuselage, version of the composite-made Cyclone.

The vehicle is powered by the new autopilot board Chimera! which executes the control algorithms developed by Ewoud from Delft MAV Lab. We are currently aiming at a total autonomous mode, e.g., auto take off and auto landing.

Flying Parrot's Disco aircraft with Paparazzi

Fri, 24 Feb 2017 21:40:45 +0000

The Disco from Parrot is a fixed-wing aircraft designed for FPV with all the feature already available on their Bebop2, plus some extra things, like airspeed sensor, SBUS input and PWM outputs.

The autopilot itself is all integrated in a box called C.H.U.C.K. and it allows nice and easy flights with the SkyController2 and the Cockpitglasses, connected via Wifi.

Just like the Bebop and ARDrones, it is now possible to fly this drone using Paparazzi. Just connect to the plane, upload your code and you’re ready to go! Here is the video of the maiden flight:

1Bitsy & Black Magic Probe Kickstarter

Tue, 29 Nov 2016 23:55:28 +0000

1Bitsy & Black Magic Probe Kickstarter

As many of you know a programmer and debugger is a tremendously useful tool for many Paparazzi UAV based autopilots like the Lisa/MX and Lisa/S.

Our friends at 1BitSquared are running a Kickstarter to make a new revision of their Black Magic Probe JTAG SWD debugger and programmer with the addition of the 1Bitsy. 1Bitsy is a development board using the same CPU as Elle0 and Lisa/MX Paparazzi autopilots. It can serve as a good prototyping platform for payload control or for your next autopilot project.

DELFTACOPTER - Hybrid Drone on a Mission

Tue, 20 Sep 2016 19:26:38 +0000

DELFTACOPTER, an electric, long range, transitioning autonomous delta-wing helicopter, is on a mission. What mission? In this case, it’s the 2016 Outback Medical Express challenge and the MAVLab Team at TUDelft has high hopes for their hybrid aircraft.

This year’s Outback Medical Express mission requires a UAV to pick up and bring back a blood sample of an ill-fated person called “Outback Joe” located at an inaccessible roughly known location 30 kilometer away remote location with unknown terrain.

Paparazzi UAV at DefCon 24

Wed, 03 Aug 2016 22:39:16 +0000

We will be at DefCon 24. A yearly hacker conference in Las Vegas, Nevada. If you are there make sure to say hi. To get in touch just send a mention or private message to @paparazziuav on twitter or a contact us in our Gitter Discuss channel.

1BitSquared will be there selling their hardware. If you are interested send them a message to @1bitsquared on twitter. They will have Elle0, Lisa/S, Lisa/MX, Lisa/M autopilots for sale as well as Lisa/S starter kits and Quad Kits. The new Black Magic Probe v2 programming and debugging adapter will be available at the Hacker Warehouse in the Vendor area.

Drones vs. Retro-gaming: fly with a Game Boy Classic

Mon, 01 Aug 2016 22:23:44 +0000

Some time ago, I found my old Game Boy at my parents’ house. So the first thing that came to my mind was: can I fly a drone with this ? (and also where is my Mario Bros cartridge).

So I spend some time searching the web to see if I could find some idea to solve my problem. And if it seems that piloting unmanned aircraft with a Game Boy is not so common, you can find everything you need to program it!

Introduction to the G0 GPS

Mon, 21 Mar 2016 22:30:05 +0000

Dear Paparazzians,

I made a new video describing the details of the G0 Paparazzi UAV GPS receiver module. In the video I go through and describe the several design decisions we made to ensure high Signal to Noise Ratio, good multi path GPS signal rejection and overall reliability of the GPS for use in airborne robotics applications.

I hope this video is helpful. If you think so too please let me know in the YouTube comments. If you enjoyed the video make sure to like it on YouTube and subscribe to the channel.

Introduction to the Elle0 Autopilot

Thu, 03 Mar 2016 00:33:17 +0000

Dear Paparazzians,

I made a new video describing the details of the Elle0 Paparazzi UAV autopilot. Elle0 is now available for purchase in the 1BitSquared store together with the G0 companion GPS receiver. In the video I go through and describe every IO pin as well as some of the design differences to the Lisa/MX Autopilot. Additionally, I describe how you can add a battery voltage monitor to your Elle0 using a voltage divider circuit.

Paparazzi UAV on Pixhawk teaser

Tue, 01 Mar 2016 22:20:49 +0000

Hi all Open-Source enthusiasts,

Today we are happy to announce we’ll be adding an extra autopilot board to there long list of supported autopilots.

The Pixhawk autopilot board will be integrated in our next software release! The video shows the first flight with Paparazzi UAV on a Pixhawk, more videos will follow.

Why choose Paparazzi UAV?

If you are looking for an advanced, modular open-source autopilot which has features others can only dream of, you choose Paparazzi UAV.

1BitSquared launches German Store

Tue, 12 Jan 2016 14:40:12 +0000

1BitSquared has just launched their German online store. This is the first dedicated Paparazzi UAV hardware supplier in Europe.

With a store in Europe they can provide faster delivery times of Paparazzi UAV hardware for all the European users and developers. Now you can purchase Lisa/M(X), Lisa/S, Elle0 autopilots and accessories for Paparazzi UAV within Europe without having to pick up your order at your customs office. We hope this will make the entry into Paparazzi and working with the system easier, knowing that you can get new parts and hardware faster from a local supplier.

G0 GPS Module

Mon, 28 Dec 2015 11:10:44 +0000

Just in time for the new year 1BitSquared releases a new GPS module named G0. It is designed to neatly fit on top of the Paparazzi UAV Elle0 Autopilot, that they released just a few weeks ago.

G0 features the UBlox Max-7Q chipset, a large ground plane and EMI shielding. Due to the large ground plane and optional side flaps it has good multipath and EMI rejection characteristics, making it a great device to be used on fully autonomous systems that need high precision and reliable GPS reception.

Lisa/S Nano Quadcopter featured on sUAS News

Tue, 15 Dec 2015 17:41:50 +0000

In the light of the recent FAA registration limits, the great guys at sUAS News wrote an article featuring the Paparazzi UAV powered Lisa/S nano Quadcopter. This platform was developed by 1BitSquared in collaboration with the TU-Delft MAV lab team, provides all the autonomous capabilities while being way below the FAA regulated limits for registration. The Lisa/S nano Quadcopter weighs only 39g while the FAA requires all aircraft above 250g to be registred.

Multi-UAV flights for simultaneous meteorological measurements

Fri, 04 Dec 2015 13:53:30 +0000

ENAC UAV Lab team and Meteo-France (CNRS-GAME and ENM) teams have spent several days at the Atmospheric Research Center of Lannemezan (in the south of France) in order to perform experiments for simultaneous meteorological measurements through multi-UAV flight.

This was part of a research project called VOLTIGE aimed at studying the formation of cloud and fog events. One of the planes is measuring the turbulence near the ground, a second plane is flying above the cloud or the fog with a radiation sensor and the last one is making a vertical profile of temperature, pressure and humidity up to 1500 meters AGL.

Elle0 Autopilot

Tue, 01 Dec 2015 02:05:12 +0000

1BitSquared has released Elle0, a new Paparazzi UAV autopilot. Elle0 is the lowest cost autopilot developed specifically for use with the Paparazzi UAV framework. It was inspired by the Lisa/MX and Apogee autopilots and has been stripped down to the most essential features while preserving the flexibility that Paparazzi autopilots are famous for.

Here are some of the specs:

STM32F4 168MHz ARM Cortex-M4 microcontroller with FPU
- 1 Mbyte of Flash memory
- 192+4 Kbytes of SRAM including 64-Kbyte of CCM (core coupled memory) data RAM
- Cryptographic acceleration: hardware acceleration for AES 128, 192, 256, Triple DES, HASH (MD5, SHA-1), and HMAC
- True random number generator
3 axis gyroscope (connected over SPI for high speed sampling and low latency)
3 axis accelerometer (connected over SPI for high speed sampling and low latency)
3 axis magnetometer (connected over SPI for high speed sampling and low latency)
barometer (connected over dedicated SPI for low noise operation and low latency)
1 I2C auxilary sensor connection
2 TTL level serial ports for telemetry radio and GPS
2 serial input interfaces for remote control receivers (using Spektrum compatible JST connectors)
1 USB port for easy firmware upgrade
8 PWM outputs/inputs for servos or legacy PPM RC receivers
2 Analog inputs for system battery voltage and current measurement
CAN TX and RX lines are accessible

Mechanically Elle0 is designed around the 30.5mm M3 hole pattern, popularized by the Nano Quad community. But Elle0 can be used on more than just Nano Quads, it has everything on board to control anything from a small Quad through a big Octocopter to Airplanes or Helicopters. For an autonomous UAV you just need to add a GPS, Telemetry radio and maybe RC receivers. ;)

Parrot Bebop 2 Support

Thu, 19 Nov 2015 00:16:47 +0000

Parrot has released their new Bebop 2 camera quadcopter. Paparazzi UAV already has support for that new platform.

Thanks to the great work of the TU-Delft MavLab team and especially Freek van Tienen it is possible to replace the stock functionality of the Parrot Bebop 2 with Paparazzi UAV.

This change gives the platform a lot of autonomous flight enhancements like dynamic flight plans, as well as improved stabilization algorithms like the INDI controller.

Multi MAV Autonomous Flight

Sun, 27 Sep 2015 11:42:09 +0000

Rich Burton of Hooperfly made a video showcasing the flexibility and accuracy of the PaparazziUAV system running on the 1BitSquared Lisa/MX autopilot.

Using Paparazzi’s flight plan software to dictate a pattern of waypoints for three of his TeensyFly MAV’s to take off autonomously, hover, fly a rectangular pattern, hover and land. All the flight plan blocks are triggered in unison with a custom papget xml config file. The unison nature of their flight is quite beautiful to behold.

Paparazzi UAV controlled with arcade

Tue, 01 Sep 2015 21:59:54 +0000

Here is a fun demo by the ENAC UAV Lab. They are showing off the flexibility of the Paparazzi UAV system by connecting an arcade gamepad to the ground station.

PaparazziUAV Flying Robots on Slashdot

Fri, 21 Aug 2015 02:37:19 +0000

The kind folks over at Slashdot.org were nice enough to stop by the PaparazziUAV booth at OSCON 2015 to talk about flying robots. Thanks Tim for the opportunity to talk about HooperFly, the Lisa/MX autopilot from 1bitsquared and the coolest open-source UAV software on the planet, PaparazziUAV.

Here’s a link to the video: Flying Robots on Slashdot.org

Paparazzi UAV + HooperFly = Flying Robots

Wed, 22 Jul 2015 05:42:16 +0000

HooperFly made a great video showing off two of their airframes, flying completely autonomously. These robotic aircraft are based on HooperFly’s own rugged airframe design the TeensyFly and feature Paparazzi UAV powered Lisa/MX autopilots. The multi aircraft support in Paparazzi makes these types of flights possible.

Paparazzi on the Parrot Bebop

Sun, 01 Feb 2015 08:21:44 +0000

The TU Delft MAVlab team made a great video showing off the ease of use of the Paparazzi UAV system on the new Parrot Bebop platform.

BBC Interview with Bart Remes

Mon, 15 Dec 2014 09:14:07 +0000

Great BBC interview with Bart Remes, head of the Mavlab at TU Delft. Bart shows off the Lisa/S Nano Quadcopter and comments on the usefulness and safety of sub-miniature UAV.

Parrot Bebop Paparazzi Integration

Wed, 12 Nov 2014 00:00:19 +0000

As you know paparazzi is a very modular platform. To show the world how modular we are, we worked hard on implementing paparazzi into the Parrot Bebop. At the Micro Aerial Vehicle Laboratory (MAVLab) of Delft University of Technology faculty Aerospace engineering (TU Delft) we received a pre-production model of the Bebop. We did our best to have paparazzi integrated before the launch of the Bebop. If you want to follow the progress check our (youtube channel).

Building the Lisa/S Nano Quadcopter

Mon, 10 Nov 2014 08:33:10 +0000

The TU Delft MAVlab team has created an engaging tutorial showing the step by step assembly of the new Lisa/S Nano Quadcopter. With these instructions you will be flying in no time! :)

Paparazzi on the Parrot ARDrone

Thu, 16 Oct 2014 08:52:37 +0000

The TU Delft MAVlab team have made a series of tutorials for the Parrot ARDrone. Showing off the ease of use of the Paparazzi UAV system on the platform.

Getting started

Autonomous Flight

IMAV 2014 Recap

Sat, 16 Aug 2014 06:27:37 +0000

IMAV 2014 was a great experience this year. If you don’t know what it is, its a micro air vehicle competition and conference that was held in Delft, Netherlands.

During the three days of the conference, there were many very interesting talks and presentations as well as an incredible showcase of research talent during the competition. Here is a playlist of the talks, they can be found on the TU Delft MAVlab YouTube channel.

PAPARAZZI AT DEFCON 22

Fri, 01 Aug 2014 01:42:02 +0000

Paparazzi UAV and 1BitSquared will be attending this years DefCon 22 in Las Vegas, Nevada. It takes place from August 7th through 10th, 2014.

We will be at the Hak5 vendor booth, with Lisa/S autopilots, Black Magic Probe, Nano Quad kits and more. Please come by and say hi!

Drones 101 Series on HAK5 - Episodes 1-7

Wed, 30 Apr 2014 00:51:49 +0000

Piotr Esden-Tempski of 1Bit Squared is working together with Darren Kitchen of HAK5 on a series about Open Source Drones, explaining what Drones/UAV/UAS are, how to build, operate, program, and calibrate them. This series highlights Paparazzi’s hardware and software systems and their strengths.

Here is the first episode in the series titled, Drones 101- Hak5 episode 1611. In this episode Piotr and Darren build an Open-Source autonomous aerial system.

Drones 101- Hak5 episode 1612. In episode 2, Piotr and Darren discuss drone basics. How they are put together, what are their components, how they operate and what makes them special.

Paparazzi at 30C3

Fri, 27 Dec 2013 00:00:49 +0000

The 30C3 – 30th Chaos Communication Congress was held in the Congress Center in Hamburg, Germany on December 27th-30th, 2013. We were present there as part of the Paparazzi UAV Assembly.

Piotr Esden-Tempski of 1BitSquared made a presentation on Paparazzi’s History in the main events hall during the congress.

httpvh://www.youtube.com/watch?v=IePG2fzKvF0

'Small autopilot, big ideas'

Sat, 30 Nov 2013 00:09:58 +0000

The Paparazzi UAV Lisa/S autopilot has been featured in MICROmanufacturing magazine. We were excited to discover that the Guinness Book listing for the smallest autopilot system is for the Kestrel autopilot. Which is 14 grams heavier and several centimeters bigger than the Lisa/S!

Lisa/S Pre-Order

Wed, 27 Nov 2013 00:00:03 +0000

Due to popular demand, Lisa/S and SuperbitRF are available for early pre-order from 1 BIT SQUARED.

Lisa/S at TU-Delft

Wed, 28 Aug 2013 00:21:17 +0000

Our friends at the TU-Delft MAVLab have made a video showing Lisa/S flying on a Quadrocopter and Helicopter. In the video you can see the Paparazzi UAV software compiled for Lisa/S stabilize and control the aircraft. It is using the SuperbitRF module to receive control commands from a Spektrum RC transmitter. All the necessary software is integrated into the master software branch of Paparazzi.

Lisa/S The Worlds Smallest UAV Autopilot

Mon, 26 Aug 2013 00:00:53 +0000

TU Delft researchers in collaboration with 1BitSquared have designed and build the world’s smallest autopilot for micro aircraft.

Researcher Bart Remes and his team of the Micro Aerial Vehicle Laboratory at the TU Delft faculty of Aerospace Engineering in a collaboration with Piotr Esden-Tempski from 1BitSquared have designed, built and tested the world’s smallest open source autopilot for small unmanned aircraft. A smaller – and lighter – autopilot allows these small flying robots to fly longer, fit into narrower spaces or carry more payloads, such as cameras. That makes them more suitable to be used in rescue operations for example. Remes: “Our aim? Make MAVs so small and light that every fireman can fit one in his pocket.”

Lisa/S V0.1 Design

Sat, 10 Aug 2013 00:01:54 +0000

Lisa/S nano autopilot V0.1 PCB Layout video - 6 months of work in 3 minutes.

Designing new hardware takes time. Laying out a board is only part of the challenge. A lot of work goes into research about the parts and circuits to use. In the following video you can see how the whole engineering effort concludes into the final design of the board. Even though the time lapse shows only 7 hours and 48 minutes of layout work, it was spread over 6 months of engineering effort.

Autonomous Paparazzi Parrot AR Drone

Tue, 22 Jan 2013 00:00:39 +0000

At the TU Delft university of technology student teams made the impossible; possible. Now you can turn your AR Drone v2 into an autonomous drone, controlled by Paparazzi autopilotsoftware. It’s simple, Insert GPS receiver into USB port, build and upload your flight plan via WiFi, and you are done! No hardware modification needed.

Detailed instructions to get your own drone flying with a Paparazzi autopilot brain can be found by following this link

ATMOS Hybrid UAV

Fri, 06 Jul 2012 00:00:58 +0000

ATMOS, a hybrid airplane-quadrotor developed at the MavLab of TU-Delft, was awarded third place (out of 140) in the UAVForge Competition. There were more than 140 initial contestants and after several selection rounds with only 12 finalists, the paparazzi Lisa/M powered ATMOS was one of the few that could actually make it to the remote target site miles away in an RF unfriendly environment. No team fully completed the baseline objectives which is why no prices were issued. The vertical takeoff and landing, together with long range thanks to the wing and flexibility thanks to open-source paparazzi were key factors in this event [1].

Paparazzi YouTube Playlist

Tue, 08 May 2012 00:00:38 +0000

A lot of cool stuff is done with paparazzi driven UAV`s. To share what the paparazzi community is doing a youtube video playlist has been created. If you want your video to be listed in there please send a YouTube link to the mailing list.

UMARIM V1.0

Wed, 05 Oct 2011 00:00:41 +0000

ENAC Team Umarim V1.0 autopilot is now released: LPC based, on-board IMU & barometer, narrow fuselage form factor (56x25mm) and lightweight (9gr) are its main features. Add your favorite GPS receiver and it will fit in your thin light UAV prototype. But it will also do the job for a bigger UAV as well. More info here…

Lisa/M for developers

Wed, 22 Jun 2011 02:51:05 +0000

Hello everyone,

After many months of hard work we have finally reached a version of Lisa/M that is ready for a wider range of developers. Although there are still some things missing that would allow a beginning user to use it with ease, we decided it is better to provide it to all of the other brilliant non core developers and users. You can find out more about it in the Paparazzi Wiki. A big thanks go to OpenUAS for his great help with the documentation.

Aspirin IMU Release

Mon, 21 Feb 2011 23:27:48 +0000

Today we are pleased to announce the public release of our next generation IMU, Aspirin! After a lengthy research, development, and testing period we are now happy with the hardware and the software drivers for this unique IMU. It is incredibly small and light, three digital sensors packed onto a single 19x14mm PCB. The footprint allows you to integrate it into your own designs too. We are also making it available via a carrier board for drop in use on Lisa/L.

Lisa/M next generation entry level Paparazzi Autopilot

Tue, 14 Dec 2010 05:53:27 +0000

Lisa/M Bottom

As promised, we want to talk about projects we are currently working on. One of them is Lisa/M.

Lisa/M will be the medium sized Autopilot based on the STM32 Cortex-M3 microcontroller. It is part of the Lisa series of Autopilots. It is very small (50mm x 25mm), about the size of an RC receiver. We want it to be as affordable as possible so that more people can join the autonomous aircraft revolution. The final cost still needs to be determined, as we are not done with the development yet.

Lisa STM32 Paparazzi Autopilot Overview Part 1.

Mon, 06 Dec 2010 23:13:20 +0000

Many Paparazzi followers will be familiar with the popular TINY and TWOG fixed wing autopilot boards that have allowed so many UAV pilots their first taste of autonomous flight. A few will even have had the pleasure of using the Booz multicopter autopilot board. All three of these designs are based on the Phillips LPC2148 microcontroller, which has proven to be a solid performer in this role. Antoine Drouin, the genius behind the Booz board, has once again outdone himself with a completely new series of autopilot boards based on the STM32 ARM Cortex-M3 microcontroller, which has the umbrella name Lisa. The first available is the Lisa/L and it is this board that will be explored in coming articles.

Code Refactor

Sun, 01 Aug 2010 00:00:49 +0000

After many years of development, so many new autopilot boards and aircraft types have been added that a sourcecode reorganization was needed. This undertaking is started and will simplify the continuous evolution of the project.

To benefit from these important changes, it only requires you to update your airframe configuration document once. After you have updated, you should not notice the significant reorganization that is going on behind the scenes. This change will benefit your aircrafts flying successfully for the years to come. The required changes are described on Update Your Airframe Configuration.

Tiny Without GPS

Fri, 13 Jun 2008 00:00:28 +0000

The new baby autopilot is born. His name is TWOG, he weighs 8 grams and is 40.2 x 30.5mm long. He’s in good health and looks a lot like his mother Tiny v2, except for the GPS receiver. The proud parents invite you to visit the pictures and technical information album…

Tiny 2.11 Available

Sat, 15 Mar 2008 00:00:49 +0000

A number of vendors are now offering assembled and not-assembled autopilots, sensors and accessories. The software is written, the hardware is built, what are you waiting for? Getting started has never been easier! More details on the Get Hardware page.

Small and Light GCS

Wed, 06 Feb 2008 00:00:43 +0000

Looking for a small, light and cheap ground station? Paparazzi runs on the ASUS eeePC out of the box (after installing the Debian Paparazzi packages). Tested on the pre-installed Xandros distribution, on a standard Ubuntu and on the preconfigured eeeXubuntu.

Tiny 2.1 Autopilot

Thu, 13 Dec 2007 00:00:09 +0000

The new Tiny 2.1 autopilot flew nicely in a Funjet for the first time.

Antenna Tracker

Mon, 05 Feb 2007 00:00:25 +0000

Jeremie Vacher, a student at ENAC, has developed a tracker for antennas. It is functional but still needs a little bit of polishing. Anybody interested?

7 State Kalman Filter

Thu, 07 Dec 2006 00:00:47 +0000

Antoine continues to make great progress toward the holy grail of 17 state inertial navigation and releases a video showing the performance of the 7-state Kalman filtered IMU providing the attitude-heading reference system (AHRS) on his quadrotor. Note how much coffee was consumed in preparation for this video. More info on the IMU is available on the sensors page. Also, be sure to admire the schematics and source code!

2003 - 2006

Wed, 01 Nov 2006 00:00:45 +0000

Paparazzi has come a long way since it’s creation in 2003. For a bit of nostalgia browse the original website.

JMD 04 Results

Mon, 20 Sep 2004 10:18:38 +0000

Paparazzi was very successful at the JMD04 (Journées Micro Drones) competition/conference in Toulouse, France. The ENAC team won first place with the Microjet. Here is the report from Antoine Drouin.

Hi everybody

Paparazzi’s microjet won the JMD04 MAV event ( http://www.micro-uav04.net/ )

During the event, we had contact with industrials who told us they were interested in manufacturing our board. Maybe the end of the nightmare for those of you who don’t enjoy the soldering iron :)

Paparazzi V1.0

Wed, 01 Oct 2003 00:00:44 +0000

This article is based on the gallery on the original paparazzi savannah website.

The following pictures were taken between August 2003 and October 2003.

We had developed a flight controller board similar to the autopilot one. We had been able to re-use some of their code - for example radio control receiving or servos commanding. Thanks allot Trammel.

The plane now had the potential to become fully autonomous (not controlled from ground anymore).

Paparazzi V0

Fri, 01 Aug 2003 00:00:02 +0000

This article is based on the gallery on the original paparazzi savannah website.

The following pictures were taken between February 2003 and August 2003.

This was the very first version of the system. The airborne hardware was minimal. It only consisted in a GPS receiver, a pic micro-controller and a modem. The pic would transmit GPS data to the ground. The plane was steered from the ground laptop using the buddy jack input of the radio control transmitter. The plane was equipped with a genuine FMA stabilizer and we tried to pilot “through” it.