Assembling a Servo Base System
We recommend you practice working with servos by setting up a servo system of loose parts on a workbench or kitchen table. This lets you see every part of the system at once and offers a clear understanding of how things work together. This is usually much easier than starting with all the parts in separate dark corners…
Each servo will typically have a 180 degree maximum rotation. At the midpoint of this rotation is the center-of-throw position. It is best to install your servo arms so this position is near the center of the motion in which the servo will eventually need to move. Finding this position is easiest by temporarily placing a servo arm on the drive axle and GENTLY rotating it left and right to find the ends of the throw. Be careful – plastic gears can be stripped by any quick or forceful movements. Move the arm to the approximate center of that rotation, remove the arm, and re-install it pointing in the direction in the middle of the operational throw. Once connected to a Servo Base, the center of throw may also be found by pressing the yellow button on the front of the Base as detailed below.
Plug in servo motors to the 3-pin connections above the base label at “Out”. Install the first servo at the right hand side of the base; This will prevent confusion later since the setup sequence will proceed from right to left. You can use 3-pin extensions as needed to reach distant servos.
Plug the Touch Toggles in below the label at “In”. Toggles operate servos directly opposite them across the base. Place a Touch Toggle across from every occupied servo output.
Connect a 5v supply to the power inlet to the black barrel connector. We recommend a separate supply for each servo board, since they can draw quite a bit of power on startup. When the power is applied you should see the green power LED light up at the right hand side of the base. All the connected servos will move randomly for a moment, and then lock into preset positions. This is a behavior well known to RC enthusiasts.
It is important to note that the servos jumping at startup can be “out of range”, into part of the rotation that is not part of your switches throw. It is important that some spring is built into the linkage between the servo and whatever it is operating, so that delicate mechanisms are not damaged.
The yellow button on the base will center all the servo motors. Pressing it again will release them all to normal function. This can be handy to know the center of throw when setting up each servo. When centered all the Toggles will have both red and green LEDs lit, so all the lights will shine, and one light Toggles will appear a reddish amber color. When the centering circuit is active you won’t be able to operate the Setup Remote.
Using The Setup Remote To Adjust Servo Operations
To adjust the servo settings you will need a Setup Remote. This is a setup tool only used to set each servo to it’s precise limits of motion and speed, so you’ll only need one no matter how many servos you have. You will also need a DCC or Data cable; This is a six pin modular jack and cable with straight through wiring. Be careful: similar telephone cables have crossed over wiring and will damage the base.
We recommend you plug your Touch Toggles from right to left so you can see the lights flash immediately when the procedure starts. The setup procedure starts at the right-most control, so if that position isn’t occupied you won’t see anything happen when you push the first button.
The data cables and jacks can be very stiff when they are new. It is a common problem to have difficulty pushing them all the way in until they’re really snug. The clip will click when they are all the way in.
There might be a small amount of dirt or oil on the contacts from manufacture. Plugging and unplugging the cable several times should wipe away any non conductive material. A spray contact cleaner might be necessary in extreme cases for both the cable and plug.
We recommend un-powering the Base when plugging or unplugging the Remote, mostly because either action can send unexpected button presses to the Base when changing the wire. It can be very confusing to have a setup procedure start when you hadn’t touched anything yet.
Start the Setup
Remove power from the Servo Base. Plug the Data cable into the jack on the Setup Remote. Plug the other end into the similar jack on the front of the Servo Base.
Press the black “Next” button on the Setup Remote to choose which servo motor you want to set. After the first press one of the Toggles will flash. The rest of the Toggles plugged into the base will turn green and stay green even if touched. Each time you press the black button another Toggle will flash. After each of the Toggles have flashed the final press will make all the Toggles turn red for a moment, and then all the Toggles will be released back to their original positions and normal functionality. At this point you can test any of the servo motors for operation. If you need further adjustments just press the black button to flash the control you are interested in.
When the Touch Toggle is flashing for the servo motor you plan to adjust, press the blue “Select” button on the Remote. The Toggle will flash a quick acknowledgment-flicker, and then start flashing mostly-green. At this point you can move the servo position to where it should be when the Touch Toggle is green. Use the two white buttons to move the servo motor left and right. Each press will move the motor a tiny step. Holding down the button will steadily move the servo motor position.
When the “green” position is right, press the blue “Select” button again. Now after the acknowledgment-flicker the Toggle will blink mostly-red. Use the white buttons to set the position to where it should be when the Toggle is red. Press the blue “Select” button to set the “red” position.
The final step in a setting up a single servo motor starts with the Toggle’s indication switching back and forth more slowly. The servo will also steadily move from the “green” position to the “red” position and back. Using the white buttons now will slow down or speed up the motion. For the protection of the servo, the top speed is limited. Low speeds can be very slow, though when the steps are slow enough a bit of jerky-ness may be visible.
The final press of the blue “Select” button will save all your settings and move the flashing selection to the next Touch Toggle. If you don’t want to set that one just press the black “Next” button to step over it.
Repeat until done.
You can see that this is all arranged so that you can easily set one or two positions and then try them out right from your controls. You can move to the next control or go back and adjust things again if you’re not satisfied with the operation. Once all the adjustments have been made you can power-down the panel, disconnect the Setup Remote, and return it to the toolbox. All the settings will be permanently remembered until the Setup Remote is plugged in again.
Occasionally you may accidentally adjust a servo to have the same start and stop endpoints (usually from pressing the blue button more than once without making any adjustments). This can be mystifying because when the Touch Toggle is touched, the indication will change but the servo motor will not move. Try to perform the setup procedure again for that motor. Be sure to make the “red” endpoint different than the “green” endpoint.
It is always good practice to build a spring or spring action into linkage connecting a servo motor to the part being moved. The motor in a servo is geared way down and often has a very short lever arm. Even small servos can produce pounds of force, so always include at least a Z bend in your linkage wire to provide a relief in the battle of the unstoppable force and the immovable object.
You’ll want to adjust the end positions of each servos operation so that it is not heavily loaded or trying to push a linkage further than it will go. The tiny motor in the servo can use quite a bit of energy trying get to a position it can’t quite reach or keeping a heavy spring tight. They will often buzz or hum noticeably when working like this. In an extreme case they can burn out from heat buildup.
If you have a lot of work to do, you may need to think about up-sizing your servo motor. Our base will drive large servos just as well as tiny ones. If your linkage is subject to unexpected loads (like human hands trying to force things) you might want to get servo motors with metal gears instead of plastic, so they can’t be easily stripped.
Because servo motors can gobble lots of electricity to just hold their position the Servo Base is not designed to “share” power with it’s neighbors, as with our other bases. This way the eight servos of a single base have access to up to two amps of 5v electricity available from a wall plug power supply. The DC input plug is mounted in the center of the Servo Base to allow multiple bases to be positioned more closely together in tight quarters while maintaining full access to the input and output pins.
One larger power supply can be used to power multiple Servo Bases as is detailed in another paper on “Using your own power supply with Touch Toggle Bases”.