The Digilent Servo Robot Kit (SRK) provides the perfect starting point for those new to robotics, but has the power to be used for advanced designs and applications as well. The SRK pairs our powerful Cerebot™ MX3cK microcontroller development board with a rugged steel platform and all the motors, wheels, and other parts needed to build a complete robot.
This document demonstrates a simple design that will get your SRK up and running, able to move forward, backwards, and pivot left or right – all depending on which button is pressed. Using your SRK’s powerful Cerebot MX3cK microcontroller, you’ll be able to add all sorts of functionality to your robot. Add some of our extensive line of peripheral modules (Pmods™) and you can design almost anything!
Your Cerebot MX3cK can be programmed with either Microchip MPLAB® IDE or chipKIT™ MPIDE. Microchip MPLAB IDE can be downloaded for free from microchip.com. chipKIT MPIDE can be downloaded for free from github.com/chipKIT32/chipKIT32-MAX.
The demo project used in this design can be downloaded from the Servo Robot Kit product page at digilentinc.com. For more information on programming the Cerebot MX3cK with MPLAB or MPIDE, see the Cerebot MX3cK Reference Manual, available from the Cerebot MX3cK product page at digilentinc.com.
- Cerebot MX3cK
- standoffs for mounting MX3cK
- battery holder (4xAA)
- 2” Velcro Strip
- one two pin MTE battery cable
- rugged Metal Platform with Holes on ½-inch Center
- two continuous rotation GWS servos
- two servo brackets
- rugged plastic wheels and tail skid
- two Pmod brackets
- one 6” 6-pin cable
- 8/32 Machine Screws
- 8/32 Hex Machine Nuts
The rugged steel components have holes on ½-inch centers allowing Digilent circuit boards and other vendors’ products to be easily attached.
The following tools are recommended for robot assembly:
- regular and small Phillips head screwdrivers
1. Servo Brackets
2. Rear Tail Skid
Add the standoffs to the robotic kit as shown below. Set four extra screws aside to mount the MX3cK in a later step.
4. Pmod Clips
5. Battery Velcro
6. Servo Motors
First, remove the white servo wheel by unscrewing the black screw, and set them aside. Mount the servos using the remaining hardware that came with the servo mounts.
Take out the two wheels and the rubber traction bands. Stretch the rubber band around the outside of the wheel. Then, attach the wheels to the servos, and secure them using the small black screws that were removed in the previous step.
Attach the MX3cK to the standoffs using the four screws that were set aside in step 3. If the through-holes on the MX3cK and the standoffs do not line up, loosen the standoffs, and retighten them after the MX3cK is attached.
9. PmodCON3 and PmodBTN
Connect the Pmods as shown below. The PmodCON3 connects to JC 6-10 (the bottome row) and the PmodBTN connects to JD 1-4 (the top row). Take care that the pins are all connected in the correct orientation. See below. The symbol that looks like a flower should only be visible on one end of the 6 pin cable, as you look down on the RDK.
10. Cable Connectors
Connect the right servo to J4 and the left servo to J5 on the PmodCON3. The white cable must be connected to the pin labeled “SIG”.
11. Battery Case
12. Connecting the Battery
Connect the open ends of the two pin MTE battery cable to the blue screw terminal on the PmodCON3 (J6). Take care that the red wire goes in the ‘+’ side of the screw terminal, and that the black wire goes in the ‘-‘ side of the screw terminal. Then, attach the connector side of the two pin MTE battery cable to the two pin header J6 on the MX3cK as shown below. Take care that the red cable connects to the ‘+’ pin (V) and that the black cable connects to the ‘-‘ pin (G).
13. Powering Up
When you are ready to power the MX3cK, add 4 AA batteries to the battery pack, and attach the connector end of the MTE cable to the two pin header J5 on the MX3ck. Take care that the red cable connects to the ‘+’ pin (V) and that the black cable connects to the ‘-‘ pin (G)
You can now use MPIDE to program the LineFollowingSRK demo project to the board. Again, this demo project can be downloaded from the Line Following Servo Robot Kit product page at digilentinc.com. Once the board is programmed, place the robot on a lightly colored (preferably white) surface with a black line between the two middle sensors. Turn the board on and press BTN2. The robot will start moving. To stop the robot, press BTN2 again. If the robot is moving in the opposite direction than expected, then check that step 10 above has been followed correctly.