Parallax Stingray Manual page 18

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.
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.
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1
3
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
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).
Copyright © Parallax Inc.
The 24 available I/O pins are buffered through three 8-bit
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.
over-current protection
Stingray Robot (#28980)
and thermal
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