Xycom XVME 500, Manual

Page: 60 / 102

XVME-500/590 Manual
February, 1988
SETTLING TIMES for these module amplifier jumpers are as follows:
J22A - 24uSec
J22B - 10uSec
J22C - 80uSec
J22D - 16uSec (not used)
A conversion mode is selected by writing its corresponding two-bit code to bits D5
and D6 of the status/control register (see Table 3-2 Input Mode Options).
The
following subsections define each of the input conversion modes and list the
procedure for using each.
3.4.1.1 Single Channel Mode
In the single-channel mode, the module will automatically start another conversion
on the specified channel, after the low-order A/D input byte (base + 8 1H) has been
read.
Procedure
1)
2)
3)
4)
5)
Write the
81H). The appropriate control byte to the status/control register (base +
objective is to set both D5 and D6 to logic ‘0’.
Select the desired channel by writing the channel number to bits D0 thru
D4 of the gain/channel register (base + 85H).
Assuming the cor-
responding Gain RAM was properly initialized (programmed) after power-
up, the gain will not
in gain is desired).-
have to be rewritten at this time (unless a change
To initiate the first conversion, perform a “dummy” read (base + 87H), or
force a conversion by writing a logic ‘1’ to bit D7 of the status/control
register (make sure the appropriate mode and interrupt states have been
selected).
Wait until the conversion is complete (i.e., check the busy flag (bit D7)
of the status/control register, or use interrupts).
Read the results of the conversion from the A/D input register -- high
byte (base + 86H) before the low byte (base 87H), or a 16-bit read.
After the low byte is read, a new conversion will automatically be
initiated on the same channel.
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