C

What you'll need:

• At least a 5-channel RC unit. 7 channels or more is highly recommended
• Female-to female cables for each channel you'll be using. We use these short ones to minimize cable clutter.
• A power source. For electric aircraft, this is usually the ESC. For gas/nitro powered planes, your radio will need its own battery. !ArduPilot Mega normally gets its power from the RC system. (If you want to power it directly from a battery, rather than through the RC system/ESC, you can; APM has a built-in power regulator to allow this. Instructions for doing that are here).

Instructions

The main !ArduPilotMega has been revised since its original version. One of the differences is that the channel markings now follow normal RC conventions (1-8) rather than the previous version's 0-7. Here is the difference between the 1.0 and 1.4 boards:

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/IMG_4936.jpg

The following instructions will show the connections for each board.

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/ArduPilot_RC_Diagram.jpg

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/ArduPilot_RC_Diagram2.jpg

Connect your RC receiver to !ArduPilot Mega (APM) with female-to-female cables. Each channel that you want APM to control should be connected to an Input on the APM board. You MUST connect an ESC or other power source to the RC pins, to power both the RC system and the board. APM will not power those pins by itself (via USB, for example).

Typically, the channel assignments are as follows: || ** RC Channel** || Function || ** APM Connector (v1.0) ** || ** APM Connector (v1.4) ** || || 1 || Roll || 0 || 1 || || 2 || Pitch || 1 || 2 || || 3 || Throttle || 2 || 3 || || 4 || Yaw || 3 || 4 || || 5 || Autopilot control || 7 || 8 ||

Note: elevons (combined ailerons/elevator, as used in flying wings) are also supported' just connect them to the first two channels as you would to your RC receiver. You'll tell APM to do elevon mixing via a DIP switch setting in the next section.

If you're flying a V-tail, this is not currently support by the APM software. Instead, you can mix your rudder and elevator channels externally with a hardware mixer. Here's a good and very inexpensive ($3) one.

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When you follow the right-angle connector, you'll see that the signal pins are those that connect to the board furthest from the edge; the ground pins are closest to the edge. Usually signal is white or yellow; ground is black.

Plug your servos and other devices you want APM to control into the matching Output connectors. In this picture, I've connected 5 channels in and two servos out.

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/IMG_4808.JPG

The first four channels are controlled by APM's multiplexer. To use this feature you should connect the channel on your RC receiver that you want to use to select the autopilot mode to the last channel input (marked as 7 on the board) on !ArduPilot Mega.

When you place APM in your aircraft, it is very important that it face the right way. The GPS connector should face forward, and the servo cables face back. Like this (note: there's a little arrow on the bottom of the shield that point to the front, too, in case you need a reminder at the field):

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/imudirection.jpg

Installing it in your plane

When putting APM in your plane, it's important to ensure that it's solidly mounted and doesn't move around in flight. It should also be as close as possible to level when the plane is in its flying orientation. Ideally, you'll want to have it as close to the center of gravity as you can (that's where vibration is the least) and mounted on foam tape onto a solid platform.

Here's an example of one way to mount it (and the GPS module) in an !EasyStar.

http://ardupilot-mega.googlecode.com/svn/ArduPilotMegaImages/IMG_4878.JPG

(Optional) Failsafe function

When the PWM pulse width on the last channel exceeds 1750 microseconds the multiplexor switches to manual mode so that the lower 4 channels are controlled by the RC inputs rather than by the autopilot. That means that even if the APM code crashes, you will always be able to switch them back into manual control. You can override this feature by using some other channel for your mode selection and leaving the highest channel input unused. In this case you can still have a manual mode, but it will be dependent on software. There is a parameter in the autopilot header file that you use to tell the autopilot which channel input you want to use for mode selection. You can read more about APM's failsafe functions here.

Also, you can set up your system to provide a failsafe in case of radio signal loss. The first method is using a receiver which allows you to set the default PWM values that it will output if the rf signal is lost. Spektrum receivers, for example, have this feature. In this case set up the receiver so that the channel you are using for mode selection outputs a value corresponding to a switch position you will use for RTL (or AUTO). If you are using a receiver for which you can only program the throttle channel for radio loss failsafe, program it to output a value below 1000 milliseconds and enable the throttle failsafe in the header file.