Digital Signal Processing Reference
In-Depth Information
are available on the FPGA board's expansion headers. A 5V 1A power supply
pin is available on the UP3's J2 expansion connector. J4 has a 3.3V supply
connection pin and JP6 can be used as another 5V supply connection.
A small protoboard can be built to connect servos and sensors to the FPGA
board. All of the connectors and pins on the boards line up on tenth inch
centers. A 0.1” perfboard or wire wrap protoboard can be cut down to 2” by 2
7/8” so that it fits over J1, J2, J3, and J4. 0.1” 40 pin connectors to attached the
protoboard to connect to J1..4 can be mounted on the protoboard. A wire warp
protoboard with holes every .1” has solder pads that can be used to attach
connectors using solder. Point to point wiring and soldering can be used to
make connections on the protoboard from the J1..J4 connectors to the .1”
connectors used to attach servos and sensors. Small single row strips of .1”
header pins can be snapped apart to make male connectors on the board for the
servos and most sensors.
You may want to consider isolating your robot's servo or motor power supply
from the supply used for the FPGA board's logic to control the noise generated
on the supply lines by the DC motors. On larger robots, two batteries are
sometimes used. A V
unregulated
connection that does not go through the 5V
regulator and is connected directly to the UP3's power input jack is available
on JP8 and J4. The 9V supply is connected after the input power switch on the
UP3 and to JP5. This also can be used to power servos and motors, assuming
the battery voltage level is not too high. If the battery voltage is too high,
another regulator can be used for the motors.
At a minimum, decoupling capacitors connected across the servo's power
supply connections are a good idea. If you plan on having several sensors on
your robot, you may want to consider building a small PCB with header pins
for the sensor power and data connections as seen in Figure 13.19. Most R/C
servos can run on 4.8 to 6V.
13.8 Robot Projects Based on R/C Toys, Models, and Robot Kits
A second option for building an FPGA driven robot involves modifying a low-
cost radio-controlled (R/C) car or truck. Fundamentally, almost any large R/C
car or truck can be modified to work with the Altera board, although some are
clearly better choices than others.
In our robot, we used a Radio Shack (
www.radioshack.com
) R/C 4WD SUV
shown in Figure 13.20. The R/C platform affords a more robust drive train and
control; however, turning radius and noise levels are sacrificed over the smaller
FPGA-bot. The R/C SUV has a spring suspension and large soft tires that make
it operable outdoors on rougher surfaces. Following are some R/C car selection
considerations that will affect available modifications and control of the new
platform.
