First understand the nature of my situation (i.e. why I don't just use a standard radio TX). I am wanting to put a camera on a quad-copter (Arducopter w/APM) and send the video back to a PC for high level image processing (via a standard video RX/TX). I also am having the Telemetry data from the Quad come back to the same PC (via an Xbee) for further processing and integration. I am flying the quad using a standard RF TX/RX using the quad's input ports.
I would love to be able to send flight controls (pitch, roll, yaw, throttle; CH1-4) up to the quad via an Xbee and have the RF RX receive it.
So my question is, Can an Xbee send up RF commands to a standard radio RX?
No, "you are doing it wrong" as they say. Mission planner has the capability to provide joystick control to the heli over the telemetry link. One thing was quickly discovered that Xbee (specifically Xbee Pros) are not fast enough to do this reliably. It can be done, just not optimal. Further, the newer 3DR 900MHz radios and in theory the 433Mhz radios are much better at this type of link. The problem with the Xbees truely is throughput. While they work great for telemetry only data and minor adjustments, we know you cannot update the APM firmware and a number of other functions that are known to not work. The new 3DR radios are much faster. So what I'm saying is, sure you can try it but don't expect great success with your current hardware. If you upgrade to 3DR radios, you will have much better luck.
Here is a blog post on the "how" http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A7114...
Be sure to read the last pages as there are a lot of good discussions and info regarding the bandwidth requirements which I was hinting at. Further, there is good discussion on using dual Xbee links, but as I said, the new 3DR radios are better than Xbee and cheaper, so they are pretty much your upgrade path in order to do this effectively.
Hope this gets you closer to the answer.
Thanks for the information! Looks like you are saving me a lot of time and frustration. I'll look into the new 3DR tx/rx.
In the meantime, I came up with another Idea as far as how to control the Arducopter from the PC, and that is to have a standard RC Transmitter like This FS-TH9X and connect it to the PC. Then have the "Joystick" commands sent to the TX. As far as latency it seems if I can keep it under 500 ms I will be ok.
I know that has been done to run simulators, but I cant find anyone who has used the process in reverse. i.e. used it to send commands from the PC to the transmitter then from the transmitter to the drone. Any thoughts on this?
This is pretty much the results of using Xbee:
Comment by Ellison Chanon November 20, 2011 at 5:51pm
Ok, after a day of testing, here's what I found on this latency issue:
- The JoyStick interface works fine when the APM is connected via USB.
- The JoyStick interface works fine when connected via Serial Port3 (Telemetry port), directly using null modem. This means that the 56K baud is sufficient for the control of aircraft using JoyStick.
- The problem occurs, when a wireless link is connected to Serial Port3. When I connect my APC220 to the Serial Port3, I begin to get packet errors, and my link health, according to Mission Planner drops from 100%, when directly connected through null modem to 68%. This means my link speed drops below the 56K. This is insufficient for both telemetry and JoyStick control.
To decide how to solve the problem I like to find out from those who are doing this, whether they experience the same drop in link quality, when using the wireless link. (That's the percentage value in the top right hand corner of the the HUD, with the little bar graph.)
Sorry I answered the question in a roundabout way.
So my question is, Can an Xbee send up RF commands to a standard radio RX?
No, Xbee cannot "transmit" to a standard RC receiver. Even if they are the same frequency like 2.4 GHz, they are entirely different protocols and transmission patterns. This is why I said "you are doing it wrong".
You can send control commands across Xbee or another type of data radio (3DR or others) via Mission Planner, but that's not exactly the same as sending it to the RC Receiver via the inputs of the APM. I just wanted to make this clear.
Also, I should have provided the direct link to the instructions:
Page 11 describes using 2 sets of radios and also mods to the Xbees to make them faster http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A7114...
I think though that everything I've seen of the 3DR radios (I have a set) they work MUCH better than Xbees.
Ahh afraid of that. Okay well thanks for the help!
I will continue to explore other options as to controlling the drone from the ground.
Hmmm... Maybe with some crafty decoding on the APM side...
I use a connection XBee pro 2.7Ghz for 6 months, for controle my Drone.
I have create my own Controle Box ( WBCommander) with an UC Arduino Mega.
In 57Kbd, it works very fine, and I take advantage of the télémetry :)
I've never heard of 2.7Ghz until today and that looks to be far different standard than what we were talking about. Are you sure it's not 2.4Ghz?
Here's Digi's offerings http://www.digi.com/products/wireless-wired-embedded-solutions/zigb...
Again, I'm not saying it's not possible, just there seems to be known issues with Xbee Pro 900s like I have. The 2.4s might work OK, the 3DR is likely to work very well (haven't seen someone try it yet). 2.4 is reduced range VS the 900s and that's why the 900s were the recommended choice for telemetry until the 3DR radio solution came out. Not only that, but the disaster flooding that happened at the Digi plant didn't help the situation with supply either of the Xbees. http://wirelessweek.com/News/2012/05/Thai-flooding-impacts-tech-com... which luckily might have had a hand in 3DR pushing to get different radios and thus ending up with the 3DR solution.
This is an assumption that he has Xbee Pro 900MHz and it's entirely possible he has the 2.4Ghz modules.
Wilfrid, thanks for posting the link to your pic, but do you have info on the code and hardware you used? Maybe some build info and diagrams?
Sorry, it's kind of a peeve of mine when somebody posts a picture of some really cool project, with no links to the code or anything else and thus no hopes of anyone else being able to build it. I saw a few comments in your thread about the hardware but even google searching WB Commander only looped me back to your pics and the one thread about Antartica. In a DIY enviroment, that's the worst kind of bragging. Kinda like hey, see what I built-too bad you can't make one.
Hi, Yes is 2.4Gz, sorry for this mistake :)
The WBCommander (Wilfrid Babilas Commander), is build around an UC Arduino Mega + XBeePro 2.4Gz + 2 HobbyKing Joystick + VDF, The Box is made with Carbon.
Special Function is connected to speed Button, like Loiter, 3 Programmable Waitpoint, etc...
For more information (Architecture + Code + Inside Picture), i prepare a Blog, but i am very busy this Week :)
Ok, that's cool and just follow up with the link to help these guys out who are trying to build joystick control systems.
Sorry I didn't say it before but nice work! I don't want to discourage anyone from posting about the latest and greatest thing they built, and I totally get it that documentation takes time, often after the thing was built and tested.
I do hate it though when people post and do not share what they created (technically a violation of the open source code and ideas used to build the object). Open source is not Free, you gotta give the design back to the community.
One more question, I understand your basic setup but at the other end (the heli) are you using APM 1 or 2 (not that it matters) and basic Arducopter firmware? Or did you have to customize the APM firmware as well?
I ask this because the current ground station firmware I thought didn't work with current APM code. If you came up with ground code that did, well that is very usefull!
The Ground Firmware is my fully original software, with Arduino v1.
The Drone Firmware is actualy, the original v21, and Run on APM1.
Cool, so you have made a working ground control firmware with the 2.x arducopter code on the APM!!!! This makes me very happy.
Could you post a HEX or pretty please the source? Even if you don't have the documentation done? In theory, you can just attach a zip when you start a thread?