Analog Devices ADuC7024 Reference Manual page 2

AN-719
When inserted, the IRQ0 push-button switch drives
P0.4/IRQ0 high. This can be used to initiate an external
interrupt 0.
To enter serial download mode, the user must pull the
P0.0/BM pin low while reset is toggled. On the evalua-
tion 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.
Power Indicator/General-Purpose LEDs
A red power LED (D3) is used to indicate that a sufficient
supply is available on the board. A general-purpose LED
(D2) is connected directly to P4.2 of the ADuC7024. When
P4.2 is cleared, the LED is turned on; when P4.2 is set,
the LED is turned off.
Analog I/O Connections
All analog I/O connections are brought out on header J3.
ADC0 and ADC1 are buffered using an 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, with the AD8132 used
to evaluate the ADC in fully differential mode.
ADC2 and ADC5 to ADC9 are not buffered. Be sure to fol-
low the data sheet recommendations when connecting
signals to these inputs.
DAC1 can be used to control the brightness of the green
LED, D1, when connected via the S1 switch.
General-Purpose Prototype Area
A general-purpose prototype area is provided at the
bottom of the evaluation board for adding external
components as required in the user's application. As can
be seen from the layout, AV
tracks are provided in this prototype area.
(A) S3 AND S2 RELEASED
S3
(RESET = 1)
, AGND, V , and DGND
DD DDIO
S2 S3
(BM = 1) (RESET = 1)
(D) RELEASE S3
S3 S2
(RESET = 1) (BM = 0)
Figure 1. Entering Serial Download Mode on the Evaluation Board
DIP SWITCH LINK OPTIONS
S1-1 V
REF
Function: Connects the output of the 2.5 V external
reference (ADR291) to the V
of the ADuC7024.
Use: Slide S1-1 to the ON position to connect the
external reference to the ADuC7024.
Slide S1-1 to the OFF position to use the in-
ternal 2.5 V reference or a different external
reference on the V
S1-2 V
OCM
Function: Connects 1.67 V to the V
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
V
OCM
divided output of the ADR291 reference.
Slide S1-2 to the OFF position to use a dif-
ferent voltage for V
voltage to the V
Note that the V
the reference value, as shown in Table I.
V V
REF
2.5 V 1.25 V
2.048 V 1.024 V
1.25 V 0.75 V
(B) PUSH S2
S2
(BM = 0) (RESET = 0)
(E) RELEASE S2
S3 S2
(RESET = 1) (BM = 1)
–2–
REF
pin of the J3 header.
REF
OCM
of the differential amplifier to the 1.67 V,
by connecting a dc
OCM
pin of the J3 header.
OCM
value is dependent on
OCM
Table I. V Range
OCM
min V max
OCM OCM
2.05 V
2.276 V
2.55 V
(C) PUSH S3
S3 S2
(BM = 0)
pin (Pin 55)
pin of the
REV. 0