Introduction: How to Use the Actobotics Servo Controller

About: I'm a tech at Robotzone (the makers of Actobotics®). I'll be posting helpful tutorials about how to use our products and incorporating them into cool robotics and R/C projects.

In this instructable I will walk you through how to use the Actobotics Servo Controller. It's a manual servo controller meaning that it doesn't require an input from a computer, microcontroller or otherwise to operate the servos. All you need is the controller, power and servos. Check out the video to see it in action!

Step 1: Connecting Servos

There are two ways to connect servos to the Actobotics Servo Controller:

Connecting Servos (direct)

reference picture 1 for direct connection

Servos can plug directly into the board via the pins located near the CAT6 port. These pins are labeled 'S' for signal, '+' for positive and '-' for negative. This connection works with nearly any brand of servo whether it has the universal style connector or it has the tab off to the edge for added clarity of the plug orientation.

Connecting Servos (via CAT6 port)

reference pictures 2 and 3 for CAT6 connection

If you wish to increase the distance between the servos and the controller you may wish to utilize the CAT6 port. This port allows you to run a CAT6 patch cable between the servos and the controller to span the distance. While regular servo extensions (plugged into the row pins on the top of the board) may serve the same purpose this is a more polished way to run servos at a distance.
1. plug a CAT6 cable into the CAT6 port.
2. plug the other end of the CAT6 cable into the CAT6 receiving board p/n 605103
3. plug the servos into the row pins labeled '1' and '4' on the CAT6 receiving board. Be sure to properly orient the servo connector so that the signal wire is nearest the channel number on the board, positive in the middle and negative on the outside.
You'll find a jumper pin on the CAT6 receiving board. If you wish to isolate power between your servo controller and the servos you can pull this pin and power your servos from the 'AUX PWR' holes or from the spare row pins. In most cases the jumper pin would be left in place in order to share power between the controller and the servos.

Step 2: Supplying Power

The servo controller can run on 4.8-7.4VDC. If you're using a power supply make sure that the power supply can provide enough current [measured in amps (A) or millamps (mA)] to drive the servos you have selected. Whether using a battery or power supply make sure that the servos can handle the voltage being supplied to the controller. There are some servos that are only rated for 4.8V.

There are a few ways to supply power:

1. Barrel Jack(picture 1) - the servo controller has a 2.5mm x 5.5mm power jack. You can plug a 2.5mm x 5.5mm DC power plug into the jack in order to supply power. If you need a power plug to solder into a battery or power supply there are several options here.

2. Row Pins (pictures 2 and 3) - on the top of the controller there are 3 pins labeled 'Battery'. You can plug in a receiver battery to these pins and the orientation of the plug doesn't matter as long as the negative wire goes to one of the pins labeled '-' and the positive wire goes to the center pin labeled '+'. Don't let the three pins fool you, only 2 need to be used.

Step 3: Adjusting the Range of the Servos

Servos operate off of a signal sent from a servo controller. The frequency range of that signal determines the amount of rotation that will be achieved by each servo. Different brands and models of servos rotate different amounts given the same signal range sent from a controller. For this reason it's nice to have the ability to adjust the frequency sent from the controller.

Brief version: right out of the box, the controller will run most servos about 90 degrees. You can overdrive most analog servos to 180 degrees by going through the range adjustment sequence below. Not many digital servos will be able to rotate 180 degrees using the range adjustment; 120 degrees is probably more realistic. To achieve 180 degrees out of a Hitec digital servo you could use a servo programmer to reset the endpoints within the servo's internal programming and then plug the reprogrammed servo into the Actobotics Servo Controller.

While it is less common to have a project where you want to reduce the rotation of the servo, you can also use the range adjustment feature to limit the rotation.

For the techy crowd: the default PWM range of the Actobotics Servo Controller is 989 - 2013usec. The range is adjustable all the way out to 477 - 2527usec. Analog servos can typically respond to a signal range from 600 - 2400usec which usually allows for 180 degrees of rotation (exceptions do apply). Hitec digitals can run on a signal range of approximately 850 - 2150usec which yields somewhere around 120 degrees of total rotation but the servos have no response to signals that fall outside that range. To get more rotation from a digital you must reprogram how the servo responds to the signal rather than just changing the signal sent to it. Most Hitec digitals can have the endpoints reprogrammed with a Hitec servo programmer so that when a signal range of 1000-2000usec is received it'll be able to do approximately 180 degrees. On most Hitec digitals, if the endpoints within the internal programming of the servo are set to their maximums (using a Hitec Servo Programmer), the servo will rotate approximately 180 degrees given a range of 1000-2000usec sent from the servo controller.

How to adjust the signal range of the Actobotics Servo Controller:

1. plug the servos in, and power up the controller. A green LED light on the top right of the board will illuminate. Turn the knobs to make sure both servos are functioning properly.

2. take an ink pen, pencil or something small in diameter that will fit through the hole in the center of the case (if you ordered the assembled version that includes the enclosure) and press the button down for approximately 1 second. Release the button when the red LED light illuminates, indicating that you've entered in to the programming mode to set the left endpoint of each channel. Turn the knobs till you're happy with the location of the servos. This will become the left endpoint.

3. take your pin and press and hold the button down for 1 second. Both the red and green LED lights will illuminate indicating that you've entered in to the programming mode to set the right endpoint of each channel. Rotate the knobs till you're happy with the location of the servos. This will become the right endpoint.

4. press and hold the button down for 1 second. The green LED will illuminate indicating that the programming is done and you can now operate the servos by turning the knobs. If you're unhappy with the endpoints selected just go through the above steps and adjust as needed.

Step 4: Resetting the Controller Back to the Factory Settings

If you want to start fresh and go back to the factory settings all you need to do is remove power from the board, press and hold the programming button down, and plug power in again. Keep holding down until the LED lights stop flashing (it takes about 3 seconds).

Step 5: Mounting the Actobotics Servo Controller (assembled Version in the Aluminum Enclosure)

The back of the aluminum enclosure has 4 tapped holes (6-32 thread) that match up with the .770" hub pattern found throughout the entire Actobotics product line. When mounting with these holes keep in mind there's a circuit board inside the case so don't use too long of a screw and contact the board. The board is just beyond .2" above the very bottom of the box so if you're mounting to any material with a thickness between .05" and .1525", a 1/4" length screw would be adequate. Any material with a thickness between .1125" and .215" could use a 5/16" length screw. Any material with a thickness between .175" and .2775" could use a 3/8" length screw.

The actual thread depth is .0975" so make sure you select a screw that utilizes the entire amount of threads for max holding power.

Step 6: Mounting the Actobotics Servo Controller (bare Board, No Case)

If you've purchased the version that comes without the case you can mount the board using the 4 holes located on the corners. These holes are 1.061" apart from top to bottom and 2.561" from side to side in order to match up with the continued hole pattern found on the Actobotics Channel. You can run 6-32 tapped standoffs to space the board off of the channel and then run 6-32 screws through the board to fasten it to the standoffs or you can run nylon spacers between the channel and the board, long screws through the board, through the spacer and through the channel and into a tapped object (screw plate or 6-32 nut).

The potentiometers will conveniently line up with the 1/2" holes in the channel so you can stick them through the channel holes if you wish. With a proper height even the power jack will be accessible/usable (.375" standoffs used in picture for proper alignment).

Step 7: Potentiometers (for Those Who Purchased the Unassembled Board)

you will receive potentiometers and row pins with your circuit board.

potentiometers: these can be soldered into the top or the bottom of the board as you choose.

pins: the row pins can be soldered into the top of bottom of the board so that you can connect a male servo lead to the board and run it out to a remote-mount potentiometer. The wiper is in the middle and reference on either side so be sure to connect the wires to the proper poles of the remote mount potentiometer you intend to use.