Digilent 410-145P - Manual (Page 2)

Digilent, Inc. Cerebot Nano Reference Manual
www.digilentinc.com page 2 of 6
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
Features of the ATmega168 include:
•
master/slave serial peripheral interface
(SPI)
• programmable serial USART interface
• Atmel two wire serial interface (TWI)
•
eight channel, 10-bit ADC
•
two 8-bit timer/counters
•
one 16-bit timer/counter
•
16KB program flash
•
512 byte EEPROM
•
1KB internal SRAM
• analog comparator
•
built-in 8MHz/1MHz clock source.
For more information on the ATmega168
microcontroller, refer to the data sheet
available at
www.atmel.com .
Functional Description
The Cerebot Nano is designed for embedded
control and robotic applications as well as
microprocessor experimentation. Embedded
firmware, suitable for many applications, can
be programmed into the Cerebot Nano’s
ATmega168 microcontroller.
Although the Cerebot Nano can be used as a
stand-alone microcontroller board, it is also
designed to be part of a larger system using a
distributed processing architecture. Connector
J1 allows the Cerebot Nano to be plugged
directly into other Digilent microcontroller
boards, such as the Cerebot II or Cerebot Plus.
The Cerebot Nano can be plugged directly into
ports on many of Digilent’s FPGA boards,
although some boards may require the use of
the Digilent Module Interface Board.
The Cerebot Nano can be programmed with
firmware to perform local control functions. It
can then be controlled by, and report back to, a
higher level controller in the host controller
board. For example, the Cerebot Nano could
be programmed to perform closed-loop motor
speed control. It could relieve extra work for
the host processor, when performing the motor
speed control, by processing commands from
the host and controlling the motors itself.
Communication Options
Connector J1 provides access to the
master/slave SPI. SPI is a high-speed,
synchronous, serial interface used by many
serial peripheral devices like ADCs and DACs.
The SPI interface is used for programming the
ATmega168 and as a user-accessible SPI
port. The Digilent PmodAD1 and PmodDA1
modules use the SPI interface.
Connectors JB and J2 provide access to the
Atmel two-wire interface (TWI). The TWI is a
medium speed (200-400 Kbps) serial bus that
allows up to 128 devices to be connected.
Connector J2 can be used to daisy chain other
devices to the TWI bus. Atmel’s TWI interface
is directly compatible with Phillips’ I
2 C protocol.
The ATmega168 microcontroller provides a
USART that can be used for asynchronous or
synchronous serial communications. However,
the Cerebot Nano doesn’t provide for a crystal
oscillator, and the internal RC oscillator isn’t
accurate enough for reliable asynchronous
communications. It is sometimes possible to
tune the oscillator using the calibration register
to allow asynchronous communications to
work.