X9241
Cascade Mode
DW bit of the WCR is set to “0” the wiper is enabled;
when set to “1” the wiper is disabled. If the wiper is
disabled, the wiper terminal will be electrically isolated
and float.
The X9241 provides a mechanism for cascading the
arrays. That is, the sixty-three resistor elements of one
array may be cascaded (linked) with the resistor ele-
ments of an adjacent array.
When operating in cascade mode VH, VL and the wiper
terminals of the cascaded arrays must be electrically
connected externally. All but one of the wipers must be
disabled. The user can alter the wiper position by writing
directly to the WCR or indirectly by transferring the
contentsofthedataregisterstotheWCRorbyusingthe
Increment/Decrement command.
Cascade Control Bits
The data byte, for the three-byte commands, contains 6
bits (LSBs) for defining the wiper position plus two high
orderbits,CM(CascadeMode)andDW(DisableWiper).
The state of CM enables or disables (normal operation)
cascade mode. When the CM bit of the WCR is set to “0”
the potentiometer is in the normal operation mode.
WhentheCMbitoftheWCRissetto“1”thepotentiometer
is cascaded with its adjacent higher order potentiometer.
For example; if bit 7 of WCR2 is set to “1”, pot 2 will be
cascaded to pot 3.
When using the Increment/Decrement command the
wiper position will automatically transition between
arrays. The current position of the wiper can be deter-
mined by reading the WCR registers; if the DW bit is “0”,
the wiper in that array is active. If the current wiper
position is to be maintained, a global XFR WCR to Data
Register command must be issued before power-down.
ThestateofDWenablesordisablesthewiper.Whenthe
Figure 9. Cascading Arrays
VL0
VH0
POT 0
WCR0
VW0
VL1
POT 1
WCR1
VH1
VW1
VL2
POT 2
WCR2
VH2
VW2
VL3
POT 3
WCR3
VH3
EXTERNAL
=
VW3
CONNECTION
3864 ILL F16.1
8
XICOR [ XICOR INC. ]
