As I mentioned earlier, we’ve got an AR Drone to play with. One of the common mods that popped up on the internet were ways of extending the range on the AR Drone. It normally uses a local Wi-Fi connection to your phone or tablet for control and video signals. Many found this quite restrictive and have gone pretty far in extending that range. The first and easiest was just to set up a higher power Wi-Fi Bridge where you’ll be flying. The Drone only has about 15db of wi-fi magic in it, so anything stronger than that is an improvement. There were too many variations on this to delve into the details, but as you see, there’s not much too it. The second method is to completely replace the Wi-Fi control system with a nice R/C controller. This will greatly increase your range as well as give you extra channels for triggering different attachments (usually lights).  I’ve seen two main methods used. One is called “MacGuyver mod”. This one is a plug and play kit that doesn’t seem to have much info along with it.

The other is called “MiruMod” and the creator has shared all the information they can.  You can find a parts breakdown as well as schematics, wiring diagrams, instructions, and software. [Miru] uses an Arduino Pro Mini or an Arduino Nano as a go-between from the receiver to the serial port on the AR Drone. You can see in the wiring diagram below that it is a fairly simple install, and all [miru] asks for is that maybe you donate some beer money if you appreciate his mod.I have started to work on DroneProxy some time ago to work around bugs in the firmware of the drone. Basically it is a transparent proxy for the UDP AT command packets arriving on port 5556. The packets are parsed to keep track of the sequence number. If no packets are received for 1500 ms the proxy will start sending “landing” commands with increasing sequence numbers (until somebody plugs the battery…). If you wondered how the update process to version 1.3.3 would look if you attached a serial console….

During my telnet visits to the Parrot AR.Drone i wondered what all the serial ports (/dev/ttyPA0..And now I know which one is used by what and where i can find them on the board.difference entre parrot ar drone 1 et 2 The pinout for a USB cable can be found at the official Parrot website….here.parrot ar drone tweaks /dev/ttyPA0 is used by the bootloader and the kernel and can be found on the “USB” port (Pin 4 is RX and Pin 6 is TX) and greets us with:parrot ar drone le bon coin This serial interface should allow us to attach a GPS module (with a TTL level serial interface) directly, without the need of a new kernel! ar parrot drone reichweite

GPS here we come! /dev/ttyPA1 is used to interface with the motor controllers. There must be some de-multiplexer between the serial port and the 4 motor controllers. parrot ar drone engadgetI actually managed to randomly start a motor by typing garbage into this.parrot ar drone steuern /dev/ttyPA2 connects to the navboard and continously spits out navdata from all sensors. After Parrot finally released the GPL sources for their kernel changes it was time to dig into the firmware some more. Last week i was taking a closer look at the closed source control binary which has the innovative name “program.elf”. It turns out that the binary dynamically links to libiw (from the wireless_tools) which is a GPL licensed library. You can easily check this yourself by telneting into the drone: Antoine Ferran (from Parrot) confirmed this fact on the next morning:

The libiw is dynamically linked with the program but it is a mistake. Libiw is not needed anymore: it is a remnant of a previous test version. Any calls to libiw has been removed from the current build that will be released soon. You can find the complete discussion here. I am pretty confident that they will not get away with that and will have to release the source code. Actually that could be a really good way for Parrot to get help from the community to fix all of the critical bugs in the current firmware (“fly-away” syndrom, random crashes, ….) and make a much better product! Now that i am done messing with the software and actually completing a few test flights, I figured it was about time to tear the drone apart. The only thing required is a tiny torx screwdriver (T6X20) which fortunately i had laying around on my desk because we use the same screws to tighten the GSM modules on to our GSM cards. Once you remove the plastic shielding you can see the mainboard stacked on top of the navboard (which carries the ultrasonic sender/receiver).

The front camera is connected with a ribbon cable coming from the right. Above that camera connector is a 7 pin USB header. Undo 4 little screws and you can remove the navboard (which plugs into the backside of the mainboard with an 8 pin connector…probably serialish). Here you see the mainboard with the camera cable removed and the battery connector ripped out of the shell (to give some space for moving the mainboard). The mainboard has 2 on-circuit wifi antennas (ANT1 and ANT2): This is the navboard with the ultrasonic sender/receiver pair. The “ugly padding” on the left is probably to shield the right one from receiving the “echo” through vibrations across the pcb (instead of receving the reflected signal through the air). The 8 pin connector connects to the mainboard. The other side of the navboard: And the other side of the mainboard: The drone is really easy to take apart and also to re-assemble. It even does work again.Please, wait while we are validating your browser