User`s manual

3-2 Universal Command Converter Motorola
Host Computer Hardware
dependent upon the host computer bus speed and its operating system. This section
describes the host computer interface hardware and software components.
3.1.1 Host Computer Bus Interface Card
Figure 3-1 shows a block diagram of the host computer interface card for all computer
platforms. The interface consists of three fixed addresses in the host computer I/O
memory map. The host computer’s interface card address zero is used as a control port for
selecting, resetting, or interrupting one or more command converters. Address one reads
and writes eight bit data bytes to one or more command converters. Address two
acknowledges command converter service requests and selects group members for
multiple command converter commands. All data is passed high-order byte first. For
example, in a 32-bit transfer, bits 31–24 are transferred first, followed by bits 23–16, bits
15–8, and then bits 7–0.
Figure 3-1. Host Computer Bus Interface Card
The ADS user interface program allows as many as eight command converters to be
addressed using one host computer interface card. Command converters may be addressed
in groups or individually depending upon the command and command arguments entered
by the user.
Host computer interface card address zero has eight output control lines. These output
control lines are asserted using positive logic (V
OH
= TRUE). Three address zero signals
BUS ADDRESS
ADDR
DECODER
CTRL
BUS
CTRL
BUS
DATA
LOCAL DATA
+5V AND GND
HOST COMPUTER BUS
CTRL1
DATA
CTRL2
37-PIN CONNECTOR
BUS INTERFACE
TO COMMAND CONVERTER(S)
R
/
W
OE
AD0
AD1
AD2
AA1973