RM2C
Understanding
Connections on
the Robot Control
Board (RCB).
In the following slides, The RCB
components will be documented in
detail so that the intended purpose
of each part is understood.
The Black SPDT switch is used to cut
on and cut off the power to the board.
THE 1n4004 Diode is used to limit REVERSE
CURRENT through the circuit if the voltage is
accidently applied in reverse.
The GREY
stripe on the
DIODE is the
NEGATIVE
side or
“CATHODE”.
The
POSITIVE
side of the
DIODE is
called the
ANODE.
The green POWER CONNECTOR is where power
is connected to the circuit board. The board should
be powered on 12 Volts DC.
You can see in this
photo that I marked the
power connector with a
+ and - sign to be sure I
didn’t incorrectly
connect power to the
circuit. Be sure to screw
the terminals down snug
to hold the wire in place.
Also, be sure that the
wires are pushed
completely into the
sockets with NO
insulation showing!
The DISC CAPACITORS in the circuit are used to keep
the power source stable so that the voltage doesn’t
fluctuate greatly when big loads such as servo motors are
powered.
The value of
these
capacitors is
.1 uF. These
are SMALL
capacitor
values
designed to
handle high
frequency
shifts.
The 5 Volt Regulator steps the voltage from the power
source down to 5 volts to power most of the essential
motors, sensors, relays and actuators that are necessary.
The 5 Volt Regulator can
handle 5 AMPS of current
and so a HEAT SINK is
required to help keep the
part cool.
The CENTER ROW of all
the header pins is
connected to the 5 Volt
regulator!
Center Row
Center Row
5 volt regulator
The 3.3 Volt Regulator powers the Propeller chip
and the XBEE Network Controller.
The 3.3 Volt Regulator
can handle up to 3
AMPS of current and it
also requires a HEAT
SINK to keep it cool.
This regulator gets its
power from the 5 volt
regulator.
3.3 Volt
The HEADER PINS are connection points to Pins
on the Propeller Chip as well as connections to
Positive 5 Volt and Ground.
Each set of
three header
pins is
organized with
the Propeller
Pin Closest to
the chip, +5 V in
the middle row
and Ground in
the outside row.
+ 5 Volt
The ULN2803 AMP/DRIVER Is used to
pull-up voltage for driving items like
stepper motors and relays.
ULN 2803A
Header Pins
are provided
on EACH side
of the
ULN2803 A to
allow
connections to
the chips
INPUT and
OUTPUT Pins.
Header Pins
The 5 Volt RELAY is provided to support
the control of Solenoids and Pneumatic
devices.
A RELAY is an
Electromechanical
switch that uses a
SMALL voltage to
control a LARGE
voltage. The use of
the relay can allow
the user to use the
3.3 v output of the
PROPELLER CHIP to
control devices of 12
Volts and higher.
5 Volt Solid State RELAY
The RESISTORS on the circuit board
are used to limit the flow of current.
1k Resistors
The 10K
RESISTOR is
being used to
provide
ISOLATION
between the
connection on
PIN 12 and
POSITIVE
Voltage.
10K Resistor
The four 1K
RESISTORS shown
here are to provide
current limiting to
pins 12 – 15 where
the PS2 Controller is
to be connected.
The XBEE WIRELESS NETWORK CONTROLLER is
the device which sends the wireless signal from
the PS2 controller to the receiver which is on the
ROBOT.
Generally used to
control signals in a
wireless computer
network, the XBEE
has its own internal
software and can be
programmed separate
from the Propeller.
The YELLOW (RX) and GREEN
(TX) LED’S, beside the XBEE,
are used to indicate data
transfer.
The XBEE is directly connected to PIN 4 and PIN 3 on the Propeller Chip.
These two pins are affected in Propeller Programming and open the
communication channel between the two XBEE’s.
The PROPELLER CHIP shown below is a
MICROCONTROLLER that can be programmed to
perform many electronics processes at the same time.
Although the CHIP itself is NOT labeled, the sticker
below the chip shows the actual PIN connections on the
PROPELLER CHIP.
This CHIP is the CORE of
the ROBOT CONTROL
BOARD (RCB). This chip
enables the operation of all
the robotic parts through
computer programming.
The Angled FOUR PIN HEADER is used to connect
the computer to the PROPELLER through a PROP
PLUG.
The PROP PLUG connects to the 4 PIN HEADER with the
silver USB connection faced UPWARD (As Shown)
The last part we will discuss is the 24LC256
EEPROM memory chip. Its purpose is to SAVE
the programs that you download onto the
Propeller chip for reuse , even if you remove
power from the board.
This chip is a
FLASH MEMORY
device which
saves the code
you download to
the Propeller
WHEN you use
the F11 key!
24LC256 EEPROM