Xycom XVME 590, Manual

Page: 35 / 102

XVME-500/590 Manual
February, 1988
2.6.4.4
Conversion Resolution
(J2A, J2B)
A jumper has been provided to change the ADC to an eight-bit converter. This will
allow a faster conversion (if required by the user), but will decrease conversion
resolution.
If this option is chosen, the lower 4 data bits will have to be masked
by software. Table 2-10 shows the conversion resolution jumpers.
Table 2-10. Conversion Resolution Jumpers
I
Conversion Desired Jumper Installed
12-bit J2A
8-bit J2B
Figure 2-5 shows the various formats of the data input register when either J2A or
J2B are installed.
High Byte Low Byte
D I I DIO
D 6
DI D O
Base + 86H
Base + 87H
J2A 12-bit r e s o l u t i o n ( b y t e s D I I - D O )
J2B 8-bit resolution (D11-D4)
(D3-D0 i g n o r e d
by software)
Figure 2-5. How Jumpers Change the Data Register
2-19