Parallax Stingray User manual

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Forums: forums.parallax.com
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Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 1 of 26
Stingray Robot (#28980)
The Stingray robot from Parallax Inc. provides a mid-size platform for a wide range of robotics projects and
experiments. The Propeller Robot Control Board is the brains of the system providing a multiprocessor
control system capable of performing multiple tasks at the same time. The Propeller chip provides eight 32-
bit processors each with two counters, its own 2 KB local memory and 32 KB shared memory. This makes
the Propeller a perfect choice for advanced robotics and the Stingray robot.
Features
•Multicore Propeller chip based control board
•Extra large EEPROM (64 KB) for storing additional
data
•On-board 3.3 V & 5V switching power supply
•5 V I/O translators to simplify interfacing to 5 V
sensors/devices
•Integrated dual full bridge driver
•Two DC spur gear motors
•Two-wheel differential drive system with rear omni-
directional wheel
•Multiple mounting locations for sensors, add-ons,
etc.
•Free online Propeller Tool programming software for
Windows and example Stingray source code
(requires Win2K/XP/Vista, IE7 or higher, and USB port)
Key Specifications
•Power requirements: 6 AA 1.2 V Rechargeable Batteries (not included)
•Communication: USB A to Mini B Cable (included)
•Operating temperature: 32 to 158 °F (0 to 70 °C)
•Dimensions, assembled: 13” L x 10.9” W x 5.5” H (33 x 27.7 x 14 cm)
Prerequisites
This document covers assembly of your Stingray robot and testing of its motors. The Stingray is intended for
those with previous programming and electronics experience, specifically prior experience with the Propeller
chip microcontroller. The following resources are recommended for Propeller beginners:
•Propeller Education Kit Labs: This educational text is a great way to get started with the Propeller.
It focuses on general Propeller programming and interfacing. The complete PDF and source code are
included in the Propeller Tool v1.2.6 or later Help file.
•The Propeller Manual and Propeller Datasheet: These invaluable reference materials are also
included in the Propeller Tool v1.2.6 or later Help file.
•The Propeller chip Forum (www.forums.parallax.com) At the top of the Propeller forum there is a
sticky thread titled “Propeller: Getting Started and Key Thread Index.” This link contains a wealth of
information from Parallax and other sources for getting started with the Propeller.

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 2 of 26
Bill of Materials
This table contains a complete list of the parts used in this kit at the time this document was created. Parts
and quantities are subject to change without notice. If you have any questions about your kit contents,
please contact Parallax through the Tech Support Resources listed on page 26.
Part # Description Quantity
28230 Propeller Robot Control Board 1
27950 Motor, 7.2VDC, 310 RPM, 6mm Shaft 2
130-32000 PE Kit Project Parts 1
452-00060 Battery Retention Clip, 6 AA 1
500-00001 Transistor, NPN, Switching, 200 mA 4
700-00028 Screw, Zinc, Pan Head, Phillips, #4-40, ¼” 16
700-00064 Parallax Screwdriver 1
700-00077 Breadboard, 3.19” L x 1.65” W 1
700-00081 Breadboard, 30 Row X 2 Column 2
710-00017 Screw, Black, Button Socket Cap, #4-40, ¼” 34
710-00018 Screw, Black, Button Socket Cap, M3, 6mm 6
710-00019 Screw, Black, Phillips Flat Head, #4-40, ¼” 2
710-00020 Screw, Zinc, Pan Head, Phillips, #8-32, 3/8” 4
712-00004 Washer, Zinc, #6 ID, 3/8” OD 2
713-00001 Standoff, Aluminum, ¼” W, Round, 5/8” L, #4-40 8
713-00017 Nut, Black Oxide, #4-40 2
721-00008 Wheel, 4-7/8” Diameter, Blue Tread 2
721-00009 Wheel Hub, Aluminum, 6 mm Shaft (includes o-ring and set screw) 2
725-00062 Hex Key, 1/16” 1
725-00068 Hex Key, 2 mm 1
730-00050 Stingray Chassis Plate 2
730-00051 Stingray Motor Mount Plate 2
730-00052 Stingray Sensor Mount Plate 5
730-00053 Stingray Tail Wheel Mount Plate 1
730-00054 Multi-Directional Tail Wheel (Omni-Wheel) 1
730-00055 Stingray Tail Wheel Axle 1
730-00056 Handle, Aluminum, 3” Length, #8-32 Screw 2
730-00057 Breadboard Mounting Plate 1
753-00003 Battery Holder, 6AA, 12” w/Connector 1
800-00037 Jumper Wire, F-M, 120mm, 10-Pack 1
800-28900 Wire, 2-Conductor (Green/White), 20AWG, 10” 1
800-28980 Wire, 2-Conductor (Blue/White), 20AWG, 10” 1
805-00006 USB A to Mini B Cable 1
Assembly Instructions
This section will guide you step-by-step as you assemble your Stingray robot. Each step will describe the
parts and tools required and then the procedure to assemble them. Each step contains a CAD drawing as a
visual aid to the instructions. Be sure to follow each step carefully.

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Preparation
9Match the Bill of Materials against the parts in your kit to make sure all parts are present.
9Find a clean workspace on which to assemble your robot. You might want to put down some
newspaper or cardboard so that the edges of the metal parts do not scratch the work surface.
9Organize tools and parts prior to starting the assembly and separate parts by type to make it easier
to gather them during the assembly process.
9Throughout the assembly process, when tightening screws be sure to get them nice and snug but do
not over-tighten them or you may strip the threads.
Additional Tools Required
Two hex keys and one Phillips/flathead screwdriver are provided. The following additional tools are required:
•Safety glasses
•Small pair of needle-nosed pliers
•O-ring pliers if you have them (these are
optional, but make things easier)
Safety first! Taking basic safety precautions is absolutely necessary when building the Stingray. The
assembly process includes steps where there is the potential for injury. For example, you will be installing
an o-ring which could fly off at high velocity if not installed properly. These dangers are minimized by
wearing safety glasses during assembly and using the right tools for the job.
Stingray Robot Assembly (exploded view of major parts)
Note: The metal parts shown in the CAD drawings have been lightened to show detail.
Multi-directional Tail Wheel
Stingray Chassis
Top Plate
Stingray Tail
Wheel Axle
Handle, Aluminum
A
ssembled Breadboards on
Breadboard Mounting Plate
Stingray Senso
r
Mount Plates
O-ring Stingray Motor
Mount
Plate
Standoff, Aluminum
Moto
r
Battery Holder and
Retention Clip Tail Wheel
Mount Plate
Wheel Hub
Wheel, Blue Tread
Motor Wire
A
ssemblies
Propeller Robot Control Board

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STEP 1: Chassis Assembly (lower)
Parts Required
•(1) Stingray Chassis Plate
•(5) Stingray Sensor Mount Plate
•(2) Stingray Motor Mount Plate
•(1) Stingray Tail Wheel Mount Plate
•(16) Screw, Black, Button Socket Cap,
#4-40, ¼”
Tools Required
91/16” Hex Key (included)
9Use the 1/16” Hex Key and the black #4-40 black button socket cap screws in this step. (Note that
there are also 6 button socket cap screws and a 2 mm Hex Key; be careful to use the correct type.)
9Attach the Tail Wheel Mount Plate and Sensor Mount Plates to the Chassis Plate in the orientation
shown below.
9Attach the Motor Mount Plates, being very careful to orient them correctly so that one screw hole is
close to the Chassis Plate, which will be the bottom of the robot.
Tip: An easy way to do this step is to attach the Tail Wheel Mount Plate first, then attach the front Sensor
Mount Plate. Now if you turn the Chassis Plate upside down each mount plate will slide right into position
and should be easier to attach.
Stingray Sensor Mount Plates
Screw, Black, Button Socket Cap, #4-40, 1/4”
Stingray Sensor
Mount Plate
Stingray Tail Wheel
Mount Plate
Motor Mount
Plate
Motor Mount
Plate
Stingray Chassis
Plate
Orient Motor
Mount Plates so
one screw hole is
close to the lower
Chassis Plate

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STEP 2: Motor Installation
Parts Required
•(2) Motor, 7.2 VDC, 310RPM, 6 mm Shaft
•(6) Screw, Black, Button Socket Cap, M3, 6 mm
Tools Required
•2mm Hex Key (included)
9Using the included 2 mm Hex Key attach the motors to the Motor Mount Plates using 3 each of the
M3 screws as shown in the figure below. The main body of the motors should be toward the bottom
of the robot while the shaft should be toward the top.
9Be sure all three screws in each motor are very snug, but do not over-tighten.
Please note that the six M3 screws look very similar to the ones used on the chassis assembly in the
previous step. To distinguish them from the others you can see that the hex hole in the head of the M3 is
larger and uses the 2 mm (larger) Hex Key.
Motor Mount
Plate
Motor Mount Plate
Screw, Black, Button Socket
Cap, #4-40, 1/4”
Assembled Lower Chassis
Motors
Front End of
Stingray Robot
Tail End of
Stingray Robot
Right Side of Stingray Robot
Left Side of
Stingray Robot

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STEP 3: Motor Wire Connection
Parts Required
•(1) Wire, 2-Conductor (Green/White), 20AWG, 10”
•(1) Wire, 2-Conductor (Blue/White), 20AWG, 10”
Tools Required
•None
There are two Motor Wire Assemblies. One has a Green/White wire pair while the other has a Blue/White
wire pair.
9Connect the Green/White Motor Wire Assembly to the left motor (shown) so that the green wire
connects to the positive terminal and the white wire connects to the other terminal. See the figure
below for details.
9Repeat the procedure for the right motor making sure to connect the blue wire to the positive
terminal and the white wire to the other terminal.
Left Motor
Green/White Motor Wire Assembly
Left Motor
Other Terminal
Connect to white wire
Left Motor
Positive Terminal
Connect to green wire

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 7 of 26
STEP 4: Hub Installation
Parts Required
•(1) Wheel Hub, Aluminum, 6mm Shaft
•(4) Hub Set Screws (included with hubs)
Tools Required
•1/16” Hex Key (included)
9Using the included 1/16” Hex Key, install 2 set screws loosely into each Wheel Hub as shown in the
figure below.
9Slide the hub onto the motor shaft so that the screws line up with the flat part of the motor shaft.
The hub should slide all the way onto the shaft with just a small gap (< 1/16”) between the hub and
the motor casing protruding through the motor mount plate.
9Both set screws should land on the flat part of the motor shaft when tightened down.
9Gently tighten the set screws. Be careful not to over-tighten the set screw but make sure it is very
snug or the hub may work loose over time.
9Repeat this procedure for the other motor.
Motor
Shaft
Hub Set Screws
Wheel Hub
Motor
Wheel Hub Set Screw holes go over
flat part of motor shaft

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STEP 5: Front Wheel Installation
Parts Required
•(2) Wheel, 4-7/8” Diameter, Blue Tread
•(2) Hub o-ring (included with hubs)
Tools Required:
•Small pair of needle nosed pliers or snap-
ring pliers (not included)
•Safety Glasses (not included)
9Be sure to wear your safety glasses during this step.
9Stand the robot on its side so that the hub and wheel are facing upward as shown in the first figure
below. This will make it easier to install the o-ring onto the hub.
9Slide one of the wheels onto a hub. You can either hold the robot chassis between your legs or
have someone else hold it in place for this step.
9To install the o-ring, place it over the hub and hold the back part of the ring in place as shown in the
upper right figure.
9Using the o-ring pliers or small needle nosed pliers, separate the front of the o-ring while pressing
down lightly. This should cause it to snap into place into the groove on the hub as shown in the
lower right figure.
9Repeat with other wheel.
Note: A video clip demonstrating how to do install the Hub o-ring with needle nosed pliers is available for
download on the Stingray product page on our website.
Wheel Hub mounted on Motor
Shaft with Set Screws
O-ring
Wheel, Blue Tread
Place o-ring over the hub and hold the back part of the
ring in place.
With pliers, separate the front of the o-ring while
pressing down lightly.
When the O-ring snaps into place into the groove on
the hub, release the pliers.

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STEP 6: Tail Wheel Installation
Parts required
•(1) Multi-Directional Tail Wheel (Omni-Wheel)
•(1) Stingray Tail Wheel Axle
•(2) Screw, Black, Button Socket Cap, #4-40, ¼”
Tools Required
•1/16” Hex Key (included)
9Be sure the two halves of the Tail Wheel Assembly are joined.
9Slide the Tail Wheel Axle inside the Tail Wheel Assembly and place it between the fins of the Tail
Wheel Mount Plate.
9Using the 1/16” Hex Key, insert the screws into each end of the axle as shown in the figure below.
9Be sure the axle screws are very snug or they may come loose over time.
Multi-Directional Tail Wheel
Stingray Tail Wheel Axle
Stingray Tail Wheel Mount Plate
Screw, Black, Button Socket Cap,
#4-40, 1/4”
Screw, Black, Button Socket Cap,
#4-40, 1/4”

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 10 of 26
STEP 7: Battery Holder Installation
Parts Required
•(1) Battery Holder, 6AA, 12” w/Connector
•(2) Screw, Black, Phillips Flat Head, #4-40, ¼”
•(2) Washer, Zinc, #6 ID, 3/8” OD
•(2) Nut, Black Oxide, #4-40
Tools Required
•Parallax Screwdriver (included)
•Small pair of needle nosed pliers
(optional, not included)
9Place the Battery Holder into the chassis so that the wires are facing the left side of the robot.
9Study the figure below to see how the screws, washers and nuts are used to secure the Battery
Holder in place:
oThe screws will go through the holes in the battery holder and then through the washers
before passing through the chassis.
oNuts will thread onto screws from under the chassis. In this manner the washers will
effectively raise the battery holder slightly from the chassis surface.
9Use the #1 Phillips screwdriver to snug the screws down. If the nuts turn while doing this you can
use the needle nosed pliers to hold them.
Battery Holder
Wires face left side of robot
Front End of
Stingray Robot
Washers
Screw, Black, Phillips Flat Head, #4-40, 1/4””
Screws
Left Side of
Stingray Robot
Right Side of
Stingray Robot
Tail End of
Stingray Robot

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 11 of 26
STEP 8: Battery Installation & Retention Clip
Parts Required
•(1) Battery Retention Clip, 6 AA
•6 AA 1.2 V Rechargeable Batteries
Tools Required
•None
9Be very careful when handling the Battery Retention clip, as the thin metal could potentially cause a
cut if you are not careful.
9Insert the 6 AA batteries into the holder being sure to observe polarity carefully. The negative side
of each battery always faces the spring in each slot.
9Once all 6 batteries are installed, slide the retention clip from the side of the battery holder. The
ends of the retention clip have tabs that, when properly installed, hook under the battery pack.
Battery Holder
Battery Retention Clip
Use 6 AA 1.2 V
Rechargeable Batteries

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STEP 9: Chassis Assembly (upper)
Parts Required
•(1) Stingray Chassis Top Plate
•(2) Handle, Aluminum, 3” Length, #8-32 Screw
•(4) Screw, Zinc, Pan Head, Phillips, #8-32, 3/8”
•(8) Standoff, Aluminum, ¼” W, Round, 5/8” L, #4-40
•(8) Screw, Zinc, Pan Head, Phillips, #4-40, ¼”
Tools Required
•Parallax Screwdriver
(included)
•1/16” Hex Key (included)
9Position the Aluminum Handles over the Stingray Chassis Top Plate. The handles will only fit in the
larger, outer slots on the left and right of the Chassis Plate.
9Using the Phillips end of the Parallax screwdriver, loosely attach the Aluminum Handles to the
Chassis Plate using the #8-32 x 3/8” screws as shown in the figure below.
9Center each handle in the grooves and tighten the screws, careful not to over-tighten them.
9Using the Phillips end of the Parallax screwdriver, install the 8 standoffs into the holes shown below.
Standoff Standoff
Handle
Handle
Outer slots
Screw, Zinc, Pan Head,
Phillips, #8-32, 3/8”
Screw, Zinc, Pan Head,
Phillips, #8-32, 3/8”
Screw, Zinc, Pan Head,
Phillips, #4-40, 1/4”
Stingray Chassis Top Plate

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 13 of 26
STEP 10: Attaching the Chassis Top Plate
Parts Required
•(16) Screw, Black, Button Socket Cap, #4-40, ¼”
Tools Required
•1/16” Hex Key (included)
9Place the Stingray Chassis Top Plate with the handles and standoffs installed over the robot.
9Bring the Motor Wires and Battery Holder Wire up through the large center hole as shown below.
9Line the Top Chassis Plate up with the holes in the Stingray Sensor Mount Plates.
9With the 1/16” Hex Key, attach the Chassis Plate using the 16 button socket cap #4-40 x ¼” screws.
Motor Wires
Battery Wire
Stingray Sensor Mount Plate
Screw, Black, Button Socket Cap,
#4-40, 1/4”
Stingray Chassis Top Plate
with Handles and Standoffs
installed

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 14 of 26
STEP 11: Breadboard Assembly
Parts Required
•(1) Breadboard, 3.19” L x 1.65” W
•(2) Breadboard, 30 Row X 2 Column
•(1) Breadboard Mounting Plate
Tools Required
•None
9Assemble the three breadboard sections so that they look like the figure below.
9Carefully remove the strip covering the adhesive backing on the Breadboard sections.
9Before adhering it to the Breadboard mounting Plate, align it carefully so you do not cover up the
mounting holes, as you won’t be able to remove and reposition it again.
9When you are sure of your alignment, stick the assembled breadboards to the Breadboard Mounting
Plate as shown by the cross-hatch area in the figure below.
Breadboard Mounting Plate
Breadboard,
30 Row X 2 Column
Breadboard, 3.19” L x 1.65” W
Do NOT stick breadboard
assembly over mounting holes

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 15 of 26
STEP 12: Installing the Breadboard and Control Board
Parts Required
•(1) Propeller Robot Control Board
•(1) Breadboard Assembly (from previous step)
•(8) Screw, Zinc, Pan Head, Phillips, #4-40, ¼”
Tools Required
•Parallax Screwdriver (included)
9Using the Phillips end of the Parallax Screwdriver, attach the Breadboard Assembly to the standoffs
closest to front end of the Stingray Robot using the #4-40 x ¼” screws.
9Place the Propeller Robot Control Board on the remaining four standoffs, oriented so that the long
row of 3-pin headers is closest to the breadboard assembly.
9Route the Battery Wire out from under the left side of the board, and the Motor Wires out from
under the right side of the board as shown in the figure below.
9Using the Phillips end of the Parallax Screwdriver, attach the Propeller Robot Control Board to the
standoffs using the #4-40 x ¼” screws.
Motor Wires
Battery Wire
Propeller Robot Control Board
Position it so row of 3-pin Headers is
closest to Breadboard Assembly
Breadboard Assembly on Stingray
Breadboard Mounting Plate
Standoff
Screw, Zinc, Pan Head,
Phillips, #4-40, 1/4”

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STEP 13: Connecting Battery and Motor Wires
Parts Required
•Assembled Stingray Robot
Tools Required
•None
9Insert the Battery Wire plug into the matching socket just in front of the DC Barrel Jack on the
Propeller Robot Control Board as shown in the figure below.
9Insert the Green/White Motor Wire plug into the Motor A socket on the opposite side of the Propeller
Robot Control Board as shown in the figure below.
9Insert the Blue/White Motor Wire plug into the Motor B socket.
Blue/White Motor Wire plugs into
the Motor B socket
Green/White Motor Wire plugs
into the Motor A socket
Battery Wire plugs into the
battery socket

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 17 of 26
Completed Stingray Robot
Propeller Robot Control Board
2
3
1
14
6
7
9
11
13
4
8
15
5
12
17
18
16
10
1. Propeller P8X32A-Q44
2. 64 KB EEPROM
3. Socketed 5 MHz Crystal
4. Right Motor Socket
5. Left Motor Socket
6. L6205 H-Bridge Driver
7. USB Connector
8. Battery Pack Socket
9. Barrel Jack, 2.1 mm
10. Power Good/Fail LEDs
11. Dual Switching Power Supply
12. Reset Button
13. 3-Position Power Switch
14. Headers to I/O P0-P23
15. Voltage Translators for I/O
16. Direct I/O Access Vias
17. VIN, 5V, 3.3V Headers
18. Ground/Mounting Vias
Front End
Left Side
Tail End
Right Side

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 18 of 26
Control Board Details
The Propeller Robot Control Board provides all the necessary base circuits needed to build a very powerful
mid-size robotics platform. The control board has an on-board USB serial interface to facilitate programming
and communication with the Propeller chip. A dual switching supply provides 3.3 V and 5 V @ up to 3 A
each. The on-board dual full bridge driver makes it possible to directly drive the Stingray’s DC brushed gear
motors with an extra motor controller. The 24 available I/O pins are buffered through three 8-bit
bidirectional voltage level translators providing direct 5 V interface capability. Finally, the input voltage can
come from the included battery pack, an aftermarket battery pack or a wall adapter using a standard 2.1
mm barrel plug. See below for details of the on-board hardware and connections.
Propeller P8X32A-Q44 [ 1 ]
The multicore Propeller chip contains 8 cogs (processors) that can operate simultaneously, both
independently and cooperatively with other cogs, sharing access to global memory and the system clock in a
round-robin fashion through a central hub. Each cog has access to all 32 I/O pins, with pin states tracked in
its own I/O output and direction registers. Each cog also has its own memory, as well as two counter
modules and a video generator. See the Propeller Manual and datasheet in the Propeller Tool Help for more
information.
64KB EEPROM (P28 – P29) [ 2 ]
The AT24C512 EEPROM (see the figure at left) chosen for the Stingray is 64KB
instead of 32KB, allowing for extra memory to store user data. This extra
memory could be used for GPS lookup tables, map data or whatever you
choose. This extra 32 KB is not overwritten when programming the EEPROM
via the Propeller Tool software. This means that when you download a new
program to the EEPROM the data in the upper 32K is not lost. The SCL line is
connected to P28 and the SDA line is connected to P29.
Socketed Crystal [ 3 ]
A 5 MHz crystal is included in the socket next to the Propeller chip. With the included crystal the Propeller
chip can run at 5, 10, 20, 40 and 80 MHz. By exchanging the crystal for one of a different value other
operating frequencies can be achieved. Refer to the Propeller datasheet for more information about using
external crystals.
L6205 Dual Full Bridge Driver (P24 – P27); Motor Sockets [ 4, 5, 6 ]
The L6205 driver is connected to the Propeller chip via I/O pins P24–P27.
P24 and P25 control Motor A while P26 and P27 control Motor B.
The L6205 used on the Propeller Robot Control Board is a Dual Full Bridge
Driver that offers many advantages in comparison to a simple H-Bridge
circuit alone. As a dual driver it can handle two motors at up to 2.8 A
(5.6 A peak) with an operating frequency of up to 100 kHz. The L6205
also provides non-dissipative over-current protection and thermal
shutdown. Internal logic eliminates the possibility of an improper
configuration of the driver that might cause a short circuit. Connections to
the output of the H-Bridge are made through the Motor A and Motor B
socket’s connectors (Molex #0351560200).
2
3
1
6
1
4
5
12

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 19 of 26
The L6205 inputs are connected to P24 through P27 on the Propeller chip. When the power switch on the
control board is set for POWER ON/MOTORS ON, the L6205 is enabled and the outputs are connected to the
motors. The truth table for controlling the L6205 is shown below in Table 1. P24 and P25 control the left
motor while P26 and P27 control the right motor. This table assumes the motors are connected to the
control board as defined in the assembly instructions.
Table 1: Motor Truth Table
P24 P25 P26 P27 Left Motor Right Motor
0 0 0 0 Brake Brake
1 0 0 0 Reverse Brake
0 1 0 0 Forward Brake
1 1 0 0 Brake Brake
0 0 1 0 Brake Forward
1 0 1 0 Reverse Forward
0 1 1 0 Forward Forward
1 1 1 0 Brake Forward
0 0 0 1 Brake Reverse
1 0 0 1 Reverse Reverse
0 1 0 1 Forward Reverse
1 1 0 1 Brake Reverse
0 0 1 1 Brake Brake
1 0 1 1 Reverse Brake
0 1 1 1 Forward Brake
1 1 1 1 Brake Brake
Note that it may be more intuitive to look at the table as two groups consisting of P24/P25 and P26/P27. In
this manner you have 4 possible combinations for each motor as shown in Table 2.
Table 2
P24 P25 Left Motor P26 P27 Right Motor
0 0 Brake 0 0 Brake
1 0 Reverse 1 0 Forward
0 1 Forward 0 1 Reverse
1 1 Brake 1 1 Brake
Pulse-width modulating one of the inputs in the opposite state of the other pin will cause that motor to move
at a speed proportional to the duty cycle of the signal. A wide range of frequencies could be used for pulse-
width modulating DC brushed motors.
The USB Serial Interface (P30 – P31)
The USB interface (see the figure at right) provides a serial connection to the
Propeller chip through the USB port of your PC. This interface is used for both
programming and communication with the control board and is based on the FTDI
FT232RL. A green LED indicates data coming into the control board and a red LED
indicates data being sent to the PC. Data coming into the control board goes to P31
on the Propeller chip while data being sent comes from P30.
2
7

Copyright © Parallax Inc. Stingray Robot (#28980) v1.1 10/6/2009 Page 20 of 26
Battery Pack Socket [ 8 ] and Barrel Jack Connector [ 9 ]
The Battery Pack Socket accepts the connector on the Stingray
Battery Pack. The Barrel Jack Connector is for use with a 6-15 VDC
wall-mount power supply, with a center positive 2.1 mm barrel
connector. NOTE: Using the Barrel Jack Connector temporarily
disables the Battery Pack Socket.
CAUTION: The input voltage (VIN) is also the motor voltage.
For this reason you should not use a wall adapter or battery higher
than 7.5 VDC when enabling the motors (power switch moved to the
third (right) position, see below). Voltages higher than 7.5 VDC can
severely reduce the life of the motors and potentially damage them.
Power Good/Fail Indicator LEDs [ 10 ]
There are actually two LEDs for power indication on the control board, one red and one green (see the
figure above). The green LED means the power is good. If the input voltage falls below approximately 6
VDC the green LED goes out and the red LED above it comes on. You may also notice when switching the
power on/off that the red LED briefly blinks while the power supply rails stabilize.
LT3501-based Dual Switching Supply [ 11 ]
The power supply uses the LT3501 Dual Tracking 3 A Switching Regulator
to provide the 3.3 V and 5 V used on the control board. This supply
regulates the 6 – 15 VDC on the input down to the desired voltages at up
to 3 A of current per supply.
Reset Button [12]
This button resets the Propeller chip, initiating its boot up procedure (see
the Propeller Help). Be aware that if the motors are running, this will cause
them to go into brake mode (see Table 1 on page 19).
3-position Power Switch [ 13 ]
The first (left) position, marked ALL OFF, turns off power to the Control Board, I/O
headers when set to 5 V, and motors. In this position the power LED is out. The
second (middle) position, marked POWER ON / MOTORS OFF, turns on power to the
control board and I/O headers, but disables the H-Bridge, effectively turning the
motors off. The last (right) position on the power switch, marked POWER ON /
MOTORS ON, turns on power to the control board, I/O headers and motors. Note
that the 3-position switch has no effect on VIN availability at the I/O headers set to
VIN, nor at the VIN power supply tap (see VIN, 5 V, and 3.3 V Power Access
Headers [ 17 ] on page 21).
Headers to 24 Available I/O Pins (P0 – P23) [ 14 ]; Voltage Translators [ 15 ]
The 24 available I/O pins are connected to three TXB0108 8-bit bidirectional voltage level translators that
convert the voltage from 3.3 V at the Propeller chip to 5 V at the I/O headers and provides some short
circuit protection with built-in 4 kΩresistors. These fully bidirectional pins are grouped as three ports with
eight I/O lines each: P0–P7, P8–P15 and P16–P23.
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