Specifications

PROGRAMMING THE S-lOO A02l2 BOARn
There are 16 I/O ports (or memory locations, depending on
the board configuration) involved in communicating with the A/D.
For 8 bit systems, these are configured to provide eight possible
READ and WRITE operations with two possible interchangeable locations
for each READ and WRITE. The READ and WRITE Register assignments
are given following this section.
The generalized algorithm for sampling an AID input is:
1) Set Command Port (Write Port 0 or 1) to desired options
(gain select; auto sequence or load enable; external strobe
enable; interrupt enable for timer
1,2, A/D overrun or AID done;
and WAIT function enable).
2) Set multiplexer address to desired input line (0 through
256). Write port 2 or 3 .
3) Start conversion. Output (or store) anything to this
port. (Write port 4 or 5).
4)
Read status of A/D. This is bit 7 of READ port 0 or
1. It is designated A/D DONE and will become 1 when the conver-
sion is complete.
5) Read low B bits of A/O from Read port 2 or 3.
6) Read high B bits of A/O from Read port 4 or 5.
The timer can be controlled as follows:
To write to the Data Port of the AM9513 timer, use WRITE
REGISTER C or O.
To write to the Command Port of the AM9513 timer. use
WRITE REGISTER E or F.
To read from the Data Port of the AM9513 timer, use READ
REGISTER C or O.
To read from the Command Port of the AM9513 timer, use READ
REGISTER E or F.
To clear timer flop 1, write to WRITE REGISTER 6 or 7.
To clear timer flop 2, write to WRITE REGISTER B or g.
The other function controlled through software is as follows:
To clear the overrun flop, write to WRITE REGISTER A or B.
The Register Assignments are given on the next two pages.
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