Analog Devices MICROCONVERTER ADUC7020 User manual

ADUC7020 EVALUATION BOARD
REFERENCE GUIDE
MICROCONVERTER
ADUC7020 DEVELOPMENT SYSTEM

ADuC7020 Evaluation Board Reference Guide
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 2 of 12 www.analog.com/microconverter
CONTENTS:
Evaluation Board Reference Guide:
1) Evaluation Board Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2) Evaluation Board Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3) DIP Switch link Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4) External Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5) Demonstration Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
6) Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

ADuC7020 Evaluation Board Reference Guide
(1) Evaluation Board Overview
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 3 of 12 www.analog.com/microconverter
(1) EVALUATION BOARD OVERVIEW
The ADuC7020 Evaluation board has the following features :
•2 Layer PCB (4” X 5” Form Factor)
•9V power supply regulated to 3.3V on board
•4 pin UART header to connect to RS232 Interface Cable
•20-pin standard JTAG connector
•Demonstration Circuit
•32.768kHz Watch Crystal to drive the PLL clock
•ADR291 2.5V External Reference Chip
•Reset/Download/IRQ0 Push Buttons
•Power Indicator/General Purpose LEDs
•Access to all ADC inputs and DAC output from external header. All device Ports are brought out
to external header pins.
•Surface mount and through hole general purpose prototype area
THIS DOCUMENT REFERS TO THE MICROCONVERTER ADUC7020 EVAL BOARD REV A1
NOTES :
1. All references in this document to physical orientation of components on the board are made with respect to a component
side view of the board with the prototype area appearing in the bottom of the board.
2. The board is laid out to minimize coupling between the analog and digital sections of the board. To this end, the ground
plane is split with the analog section on the left hand side and a digital plane on the right hand side of the board. The
regulated 3.3V power supply is routed directly to the digital section and is filtered before being routed into the analog
section of the board.

ADuC7020 Evaluation Board Reference Guide
(2) Evaluation Board Features
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 4 of 12 www.analog.com/microconverter
(2) EVALUATION BOARD FEATURES
Power Supply:
The user should connect the 9V power supply via the 2.1mm input power socket (J5). The input
connector is configured as ‘CENTER NEGATIVE’ i.e. GND on the center pin and +9V on the outer
shield.
This 9V supply is regulated via a linear voltage regulator (U5). The 3.3V regulator output is used to drive
the digital side of the board directly. The 3.3V supply is also filtered and then used to supply the analog
side of the board.
When on, the LED (D3) indicates that a valid 3.3V supply is being driven from the regulator circuit. All
active components are decoupled with 0.1uF at device supply pins to ground.
RS232 Interface:
The ADuC7020 (U1) P1.1 and P1.0 lines are connected to the RS232 Interface Cable via connector (J1).
The Interface Cable generates the required level shifting to allow direct connection to a PC serial port.
Ensure that the cable supplied is connected to the board correctly i.e. DVDD is connected to DVDD and
DGND is connected to DGND.
Emulation Interface:
Non-intrusive emulation and download are possible on the ADuC7020 via JTAG by connecting a JTAG
emulator to the J4 connector.
Crystal Circuit:
The board is fitted with a 32.768kHz crystal, from which the on-chip PLL circuit can generate a
41.78MHz clock.
External Reference (ADR291)
The external 2.5V reference chip (U2) has two functions. It is provided on the evaluation board to
demonstrate the external reference option of the ADuC7020 but its main purpose is to generate the VOCM
voltage of the differential amplifier if required.
Reset/Download/IRQ0 Push Buttons:
A RESET push button is provided to allow the user to manually reset the part. When inserted the RESET
pin of the ADuC7020 will be pulled to DGND. Because the RESET pin on the ADuC7020 is Schmidt
triggered internally there is no need to use an external Schmidt trigger on this pin.
When inserted the IRQ0 push button switch drives P0.4/IRQ0 high. This can be used to initiate an
external interrupt 0.

ADuC7020 Evaluation Board Reference Guide
(2) Evaluation Board Features
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 5 of 12 www.analog.com/microconverter
To enter serial download mode the user must pull the P0.0/BM pin low while reset is toggled. On the
evaluation board serial download mode can be easily initiated by holding down the serial download push
button (S2) while inserting and releasing the reset button (S3) as illustrated in Figure 1.
S3
(RESET=1)
S2
(BM=1)
(
A
)S3&S2RELE
A
SED
S2
(BM=0)
S3
(RESET=1)
(B) PUSH S2
S3
(RESET=1)
S2
(BM=0)
(D) RELEASE S3
S2
(BM=0)
S3
(RESET=0)
(C) PUSH S3
S2
(BM=1)
S3
(RESET=1)
(E) RELEASE S2
Figure 1: Entering Serial Download Mode on the Evaluation Board.
Power Indicator/General Purpose LEDs:
A power LED (D3) is used to indicate that a sufficient supply is available on the board. A general
purpose LED (D2) is directly connected to P4.2 of the ADuC7020. When P4.2 is cleared the LED will be
turned ON and when P4.2 is set the LED will be turned off.
Analog I/O Connections:
All analog I/O are brought out on header J3.
ADC0 and ADC1 are buffered using a AD8606 to evaluate single–ended and pseudo differential mode. A
potentiometer can be connected to ADC0 buffered.
ADC3 and ADC4 can be buffered with a single-ended to differential op-amp on board, the AD8132 used
to evaluate the ADC in fully differential mode.
ADC2 is not buffered. Be sure to follow the datasheet recommendation when connecting signals to this
input.
DAC1 can be used to controlled the brightness of the green LED D1, when connected via the S1 switch.
General Purpose prototype area
General Purpose prototype areas are provided at the bottom of the evaluation board for adding external
components as required in the users application. As can be seen from the layout AVDD, AGND, VDDIO
and DGND tracks are provided in this prototype area.

ADuC7020 Evaluation Board Reference Guide
(3) Link Options
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 6 of 12 www.analog.com/microconverter
(3) DIP SWITCH LINK OPTIONS
S1-1 VREF
Function: Connects the output of the 2.5V external reference (ADR291) to the VREF pin (pin #35) of
the ADuC7020.
Use: Slide S1-1 to the ON position to connect the external reference to the ADuC7020.
Slide S1-1 to the OFF position to use the internal 2.5V reference or a different external
reference on VREF pin of J3 header.
S1-2 VOCM
Function: Connects 1.67V to the VOCM pin of the AD8132. No extra DC voltage is required on the
board to use the ADC in differential mode.
Use : Slide S1-2 to the ON position to connect VOCM of the differential amplifier to 1.67V, divided
output of the ADR291 reference.
Slide S1-2 to the OFF position to use a different voltage for VOCM by connecting a DC
voltage to the VOCM pin of J3 header. Note that VOCM value is dependant on reference value as
shown in Table 1:
VREF V
OCM min VOCM max
2.5V 1.25V 2.05V
2.048V 1.024V 2.276V
1.25V 0.75V 2.55V
Table 1: VOCM range
S1-3 POT
Function: Connects the potentiometer output to ADC0. This input is buffered by an AD8606. This is for
demonstration purposes.
Use : Slide S1-3 to the ON position to connect the potentiometer to the op-amp of ADC0 input
channel.
Slide S1-3 to the OFF position to use ADC0 input on J3 header.
S1-4 ADC3
Function: Brings out ADC3 (pin #1) on J3 header.
Use: Slide S1-6 to the ON Position to connect directly ADC3 of J3 header to ADC3 pin (pin #1) of
the ADuC7020.
Slide S1-6 to the OFF Position to disconnect ADC3 of J3 header from ADC3 pin (pin #1) of
the ADuC7020.

ADuC7020 Evaluation Board Reference Guide
(3) Link Options
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 7 of 12 www.analog.com/microconverter
S1-5 VIN-
Function: Connects -OUT of the single-ended to differential op-amp (AD8132) to ADC3. S1-5 and S1-
6 must be used together, when VIN- is in the ON position, VIN+ must also be in the ON
position to use the differential op-amp on channel ADC3 and ADC4.
Use: Slide S1-5 to the ON Position to connect –OUT of the AD8132 to ADC3.
Slide S1-5 to the OFF Position to use ADC3 without the AD8132.
S1-6 VIN+
Function: Connects +OUT of the single-ended to differential op-amp (AD8132) to ADC4. When VIN+
is in the ON position, VIN- must also be in the ON position to use the differential op-amp on
channel ADC3 and ADC4.
Use: Slide S1-6 to the ON Position to connect +OUT of AD8132 to ADC4.
Slide S1-6 to the OFF Position to use ADC4 without the AD8132.
S1-7 ADC4
Use: Slide S1-6 to the ON Position to connect directly ADC4 of J3 header to ADC4 pin (pin #2) of
the ADuC7020.
Slide S1-6 to the OFF Position to disconnect ADC4 of J3 header from ADC4 pin (pin #2) of
the ADuC7020.
S1-8 LED
Function : Connects the DAC1 output to the green LED of the demo circuit, D1.
Use : Slide S1-7 to the ON position to connect the DAC1 output to D1.
Slide s1-7 to the OFF position to use DAC1 output on J3 header.

ADuC7020 Evaluation Board Reference Guide
(4) External Junctions (Connectors)
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 8 of 12 www.analog.com/microconverter
(4) EXTERNAL CONNECTORS:
J3 Analog I/O Connector
The analog I/O connector J3 provides external connections for all ADC inputs, reference inputs and DAC
outputs. The pinout of the connector is shown below in Table 2.
Pin # Pin Description
J3-1 AVDD
J3-2 AGND
J3-3 VREF
J3-4 ADC0
J3-5 ADC1
J3-6 ADC2
J3-7 ADC3
J3-8 ADC4
J3-9 VDIFF
J3-10 VOCM
J3-11 DAC0
J3-12 DAC1
J3-13 DAC2
J3-14 DAC3
Table 2: Pin functions for Analog I/O connector J3
J5 Power Supply Connections
J5 allows for the connection between the evaluation board and the 9V power supply provided in the
ADuC7020 Development System.
J4 Emulation Connector
J4 provides a connection of the evaluation board to the PC via a JTAG emulator, not included in the
ADuC7020 Development System.
J1 Serial Interface Connector
J1 provides a simple connection of the evaluation board to the PC via a PC serial port cable provided with
the ADuC7020 Development System.
J6 I2C Interfaces Connector
J6 provides a simple access to the two I2C interfaces of the ADuC7020.

ADuC7020 Evaluation Board Reference Guide
(4) External Junctions (Connectors)
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 9 of 12 www.analog.com/microconverter
J2 Digital I/O Connector
The digital I/O connector J2 provides external connections for all GPIOs. The pinout of the connector is
shown below in Table 3, with details of the pin functions.
Pin # Pin Description
J2-1 DGND
J2-2 P4.2
PLAO[10]
J2-3 P1.0
T1/SIN/SCL0/PLAI[0]
J2-4 P1.1
SOUT/SDA0/PLAI[1]
J2-5 P1.2
RTS/SCL1/PLAI[2]
J2-6 P1.3
CTS/SDA1/PLAI[3]
J2-7 P1.4
IRQ2/RI/CLK/PLAI[4]
J2-8 P1.5
IRQ3/DCD/MISO/PLAI[5]
J2-9 P1.6
DSR/MOSI/PLAI[6]
Pin # Pin Description
J2-10 P1.7
DTR/CSL/PLAO[0]
J2-11 P0.7
ECLK/XCLK/SIN/PLAO[4]
J2-12 P2.0
CONVSTART/SOUT/PLAO[5]
J2-13 P0.5
IRQ1/ADCBUSY/PLAO[2]
J2-14 P0.4
IRQ0/ PLAO[1]
J2-15 P0.3
TRST/ADCBUSY
J2-16 P0.6
T1/MRST/PLAO[3]
J2-17 P0.0
CMP/PLAI[7]
J2-18 DGND
Table 3: Pin functions for digital I/O connector J2

ADuC7020 Evaluation Board Reference Guide
(5) RTD Temperature Demonstration Circuit
Rev. 1.0 Analog Devices Inc., MicroConverter
Page 10 of 12 www.analog.com/microconverter
(5) POTENTIOMETER DEMONSTRATION CIRCUIT
ADC DAC
AV
DD
Application
Code
AV
DD
Figure 2: Circuit diagram of the RTD Circuit
Using the sample code pot.c in the code example folder, the variation in the potentiometer resistance can
be seen on the output LED.
Note that the internal and external reference are 2.5V, which gives an ADC input range of 0V to 2.5V in
single-ended mode. The potentiometer can give a voltage between 0V and AVDD = 3.3V.