Arexx AAR-04, Руководство пользователя, Страница: 11 / 30

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3.2 Background-information for the AAR
The front-side provides a USB-interface equipped with an FT232 IC.
This chip transforms the USB-signal into a RS232 UART-signal, which
may be processed by the ATMEGA328P Processor (located at right
side of the front position).
At the opposite side we positioned the ON/OFF-switch including a
JP3-connector for the supply-connection and the motor-controller
IC2. The back-side of the printed circuit board (PCB) has been chosen
to locate both engines and the wheel-sensors.
The wheel-sensors are using photo-eyes. The cogwheels have been
equipped with four holes in a 90°-position pattern. As soon as the
light passes a hole and hits a sensor the wheel sensor will send a
trigger-pulse for this corresponding wheel to the processor. Addition-
ally the electronic circuits switch on LED16 respectively LED17. The
trigger pulses allow us to have an accurate overview of the wheel-
speed for each of the rear wheels.
At the front-side we located the connectors for extension boards and
at the bottom-side of the PCB we will find the sensors for the line-
follower circuit.
The line-follower uses an LED to send a beam of light to the bottom
area. Alongside of the LED two infrared sensors have been positioned
to monitor the reflected light from the bottom. Additionally the PCB
provides us with the other components (LEDs, resistors and capaci-
tors) to complete the line-follower to a working module.
The robot uses an Arduino-board, which may be compared to the
Arduino Duemilanove board. The ATMEGA328P micro-controller is the
system’s core, which provides us with 14 digital I/O-ports, in which
six ports are configurable as Pulse-Width-Modulated (PWM-) output
channels. Additionally the robot has been configured with 6 analog
input channels, a 16MHz crystal oscillator and a USB- connector for
programming and control. The list may be completed with an ISP-
connector, enabling experienced hobbyists to program their own
boot-loader program.
The robot has been designed for a 5V-supply voltage and may also
be satisfied with the supply current from the USB-plug. This option is
quite comfortable for testing and programming.
Rather comfortable in this robotic concept are the connector plugs,
which allow you to insert your own extension modules or the AREXX-
extension modules from the ASURO-series.