Version 1.0 - Analog Devices ADUC824 Reference Manual

LK6 (3x1) DAC Output Link
Function: The DAC output can be routed out on one of 2 pins. This link routes the selected DAC output
pin through an external buffer to the external pin J2-13.
Use : Slide LK6 to Position A if DAC output is selected on pin 12 (P1.7/AIN4).
Slide LK6 to Position B if DAC output is selected on pin 3 (P1.2/I
Slide LK6 to Center Position if DAC output is not being used.
LK7 (3x1) REFIN- Select
Function: Allows the selection of an external reference, i.e. the AD780 or the RTD reference voltage
Use: Slide LK7 to Position A to connect REFIN- to analog ground (use with AD780).
Slide LK7 to Position B to connect the negative end of the RTD circuit reference voltage (the
voltage dropped across R11) to REFIN- (use with RTD temp demo circuit).
Slide LK7 to Center Position to connect an external reference at J2-7 to REFIN+
LK8 (3x1) REFIN+ Select
Function: Allows the selection of an external reference, i.e. the AD780 or the RTD reference voltage
Use: Slide LK8 to Position A to connect REFIN+ to the 2.5V output of the AD780.
Slide LK8 to Position B to connect the positive end of the RTD circuit reference voltage (the
voltage dropped across R11) to REFIN+ (use with RTD temp demo circuit).
Slide LK8 to Center Position to connect an external reference at J2-8 to REFIN-.
LK9 (3x1) External Data Memory
Function: This link is used to configure the external data memory map. Either the bottom 32k Bytes of
the external data memory space is mapped or the bottom 256 bytes in the first 128 pages is
mapped. (via A16-A23 and U4).
Use : Slide LK9 to Position A to make U4 transparent. Hence the external data memory (U5) sees
address lines A0-A14. Hence the bottom 32K Bytes of the address range are mapped into the
external data memory space.
Note: In this mode (using less than 64k Bytes of XRAM) the latch U4 is unnecessary.
Slide LK9 to Position B to allow ALE to latch U4. Hence the external data memory (U5) sees
the address lines A0-A7 and A16-A22. Hence the bottom 256 Bytes in the first 128 pages of
the address range are mapped into the external data memory space.
Note: This mode may not be of particular use to the user but it does show the 24 bit
addressing ability of the MicroConverter.

Version 1.0

ADuC824 Evaluation Board Reference Guide
Page 8 of 14
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