For my arduino controlled car, but it has a servo plug.. now. Before I buy it, how would I determine how to control that thing without having a receiver / remote control ? What are possible options? Where do I look for such documentation if it isn't on the manufacturer site?
Before I buy it, how would I determine how to control that thing without having a receiver / remote control ? What are possible options? Where do I look for such documentation if it isn't on the manufacturer site?
All the documentation for the controller is what you linked to.
The short answer to your question on how to control it, is to use the Servo library on the Arduino:
Now, within the documentation that you linked (and I only skimmed it lightly), there should be enough information in there telling you how to program and use it from a receiver point of view (that is, if you were using it for standard R/C control). That should be enough to go on in order to use the Servo library (if you have experience controlling regular servos using the library and Arduino).
If not, though, it might be helpful for you to buy a receiver and transmitter to play around with the controller, and gain a "feel" and understanding how it works in the normal "manual" operational mode with an R/C system. Then, you can translate that into what is needed by the Servo library.
The greatest issue on these controllers - besides programming them (which appears to be possible without needing anything very special) - is "arming" them to take the commands from the controller. There should be instructions within that document you linked (again, I only skimmed it) on how to do this, but it is important and necessary for it to work properly (indeed, for it to work at all). Basically, "arming" the controller initiates it so that it can take commands from the controlling system (whether receiver, or an Arduino with the Servo library); there is generally a particular sequence of commands that have to be sent after it is turned on in order to "arm" it - after which, it will beep or do something else (again, read the manual you linked) to show you that it is armed and ready to receive regular commands.
With the a regular R/C transmitter, you typically do this by moving the controls on the transmitter in a certain fashion, after which a beep is heard and/or an LED is lit - then you can continue the use of the controls as normal. For using an Arduino and the Servo library, you must send a similar sequence of commands; ie - Servo.write() and/or Servo.writeMicroseconds() - again, after which it indicates that it is "armed", you can send normal command sequences to control it properly.
This arming sequence is a safety feature, and most controllers have it - but it must be initiated properly after power-up, or the controller will not function. Again, having an actual transmitter/receiver handy to play with this can be super-helpful in troubleshooting and development of the Arduino Servo library code implementation.
Finally - one thing you can also do (which may or may not be useful in your project) by having an actual transmitter and receiver - you can interface the receiver to the Arduino! By using PulseIn:
...after connecting the receiver's servo output to the Arduino - and reading the pin - you can determine what your transmitter is sending. From there, you can simply "pass it thru" to the servo via the Servo library (just as if it were connected directly), or you can do more interesting things...
For instance - you could record your commands to memory (EEPROM or SDCard, likely) - then play them back! Or - maybe you have an R/C car - add a front mounted ultra-sonic sensor to the car, pass the accelerator and/or steering thru the Arduino - and if the ultra-sonic sensor "sees" an potential collision with something, it could stop the car automatically, or steer it away from it (or both).
These are just a couple of potentially interesting options in playing with R/C receivers, transmitters, controllers, and mixing the Arduino in with them all...