ADuC824 Evaluation Board Reference Guide
(2) Evaluation Board Features
Version 1.0
Analog Devices Inc., MicroConverter
Page 4 of 14
www.analog.com/microconverter
(2) E
VALUATION
B
OARD
F
EATURES
Power Supply:
A 9V supply is fed to the board via the 2.1mm input power socket (J8). The input connector is configured
as ‘CENTER NEGATIVE’ i.e. GND on the center pin and +9V on the outer shield. Alternatively the user
can connect a 9V battery via J9(-) and J10(+). The 9V supply is regulated via a linear voltage regulator
(U7), the 5V output being used to drive the digital side of the board directly. The 5V supply is also
filtered and then used to supply the analog side of the board.
When on, the green LED (D2) indicates that a valid 5V supply is being driven from the regulator circuit.
All analog supplies are decoupled with 10uF and 0.1uF at device supply pins. Digital supplies are
decoupled with 0.1uF at the digital supply pins.
RS232 Interface:
The ADuC824 (U1) TXD and RXD (pins 17 and 16 respectively) lines are connected via an RS232
transceiver (U2) to the external 9-way D-Type connector (J1). The transceiver generates the required level
shifting to allow direct connection to a PC serial port. This interface will be the main channel of
interactive communications on the board. A standard serial port cable is included as part of the
QuickStart
Development System to connect the PC directly to Evaluation Board.
Analog I/O Connections:
The inputs to the primary ADC are filtered with a first order (RC) anti-aliasing filter. There is an option
(LK5) to bias the AIN2 analog input to 2.5V. There is also an option (LK4) to short both analog input
channels (AIN1/AIN2) to allow various noise parameters to be more easily evaluated. (See section 1.2 for
Link descriptions). The DAC output is buffered before being driven to an external pin header.
A general purpose buffer configuration is provided at J2-14, J2-16 and J2-17. The buffer configuration
allows the user to control the gain and/or offset of a signal.
General Purpose prototype area
General Purpose prototype areas are provided at the top and the bottom or the evaluation board for adding
external components as required in the users application. As can be seen from the layout AVDD, AGND,
DVDD and DGND tracks are provided in this prototype area.
External Data Memory Interface:
The Evaluation board incorporates 32KBytes SRAM (U5). This external memory can be configured as a
data memory or as both code and data memory. Typically the 32Kbytes will be used as external data
memory. To configure it as such remove link 13.
The MicroConverter uses a 24-bit address interface to external memory unlike a standard 8051, which
only uses 16-bit addresses. This means that the MicroConverter can address up to 16MBytes of XRAM
while the 8051 can only address 64kBytes of XRAM. This is done by multiplexing Port2 (high address
byte + page address byte) as well as Port0 (low address byte + data byte). See page 62 of the datasheet.
