Digilent 410-145P User Manual

CCeerreebboott NNaannoo™
RReeffeerreennccee MMaannuuaal

Revision: February 6, 2009
Note: This document applies to REV A of the board.

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Overview

The Cerebot Nano is the smallest in the
Cerebot line of boards offered by Digilent. The
board’s small size allows it to be used as either
a peripheral that can be plugged directly into
other Digilent boards or as a tiny stand-alone
embedded control board. In spite of its small
size, the Cerebot Nano is packed with
features.

The Cerebot Nano’s versatile design and
programmable microcontroller allows you to
control different external devices and program
the board for multiple uses. The board has
many I/O connectors and supports a number of
programming tools including Atmel AVR
Studio® 4 and WinAVR.

The Cerebot Nano has a number of
connections for peripheral devices. Digilent
peripheral modules (Pmods™) include H­bridges, analog-to-digital and digital-to-analog
converters, a speaker, switches, buttons,
LEDs, RS232 converters, screw terminal
connectors, BNC connectors, servo motors,
and more. For more information see

www.digilentinc.com.

Features include:

• ATmega168 microcontroller

• one 6-pin and two 12-pin connectors for

Digilent Pmod peripheral module
boards

• up to eight analog-to-digital (ADC) input
channels

• four LEDs

• ESD protection for all I/O pins

• in-system programming support using

the Digilent parallel JTAG cable or the
Digilent USB JTAG/SPI cable.

16K Flash

(Internal)

512 EEPROM

(Internal)

1K SRAM

(Internal)

www. d i g i l e n t i n c . c om

215 E Main Suite D | Pullman, WA 99163

[phone] Voice and Fax

Power

connector

ATMega168

MLF32

Cerebot Nano

2

J1

SPI/

ISP

J2/

TWI

J4

ADC6/7

I/O Connectors

Cerebot Nano Circuit Diagram

4 LEDs

JA

ADCs/

IO

TM

12

USART/

Internal

Oscillator

UART, SPI,
& TWI ports

1226

JB

TWI/

IO

®

Doc: 502-095 page 1 of 6

Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

Cerebot Nano Reference Manual

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

Digilent, Inc.

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’ I2C 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.

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.