x9268us24c7979 Intersil Corporation, x9268us24c7979 Datasheet - Page 10

• Manufacturer Part Number: x9268us24c7979
• Description: Dual Digitally Controlled Xdcp? Potentiometers
• Manufacturer: Intersil Corporation

DEVICE DESCRIPTION
Wiper Counter Register (WCR)
The X9268 contains two Wiper Counter Registers, one
for each DCP potentiometer. The Wiper Counter
Register can be envisioned as a 8-bit parallel and
serial load counter with its outputs decoded to select
one of 256 switches along its resistor array. The
contents of the WCR can be altered in four ways: it
may be written directly by the host via the Write Wiper
Counter Register instruction (serial load); it may be
written indirectly by transferring the contents of one of
four associated data registers via the XFR Data
Register instruction (parallel load); it can be modified
one step at a time by the Increment/Decrement
instruction (See Instruction section for more details).
Finally, it is loaded with the contents of its Data
Register zero (DR0) upon power-up.
The Wiper Counter Register is a volatile register; that
is, its contents are lost when the X9268 is powered-
down. Although the register is automatically loaded
Table 4. Wiper counter Register, WCR (8-bit), WCR[7:0]: Used to store the current wiper position (Volatile, V).
Table 5. Data Register, DR (8-bit), Bit [7:0]: Used to store wiper positions or data (Nonvolatile, NV).
WCR7
(MSB)
MSB
Bit 7
NV
V
WCR6
Bit 6
NV
V
10
WCR5
Bit 5
NV
V
WCR4
Bit 4
NV
V
X9268
WCR3
Bit 3
with the value in DR0 upon power-up, this may be
different from the value present at power-down.
Power-up guidelines are recommended to ensure
proper loadings of the DR0 value into the WCR (See
Design Considerations Section).
Data Registers (DR)
Each potentiometer has four 8-bit nonvolatile Data
Registers. These can be read or written directly by the
host. Data can also be transferred between any of the
four Data Registers and the associated Wiper Counter
Register. All operations changing data in one of the
data registers is a nonvolatile operation and will take a
maximum of 10ms.
If the application does not require storage of multiple
settings for the potentiometer, the Data Registers can
be used as regular memory locations for system
parameters or user preference data.
Bit [7:0] are used to store one of the 256 wiper
positions (0~255).
NV
V
WCR2
Bit 2
NV
V
WCR1
Bit 1
NV
V
WCR0
(LSB)
Bit 0
LSB
NV
V
August 29, 2006
FN8172.4