X9259 Xicor, X9259 Datasheet - Page 9

• Manufacturer Part Number: X9259
• Description: Quad Digitally-Controlled (XDCP) Potentiometers
• Manufacturer: Xicor

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).
X9259
DEVICE DESCRIPTION
Wiper Counter Register (WCR)
The X9259 contains four 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 X9259 is powered-
down. Although the register is automatically loaded
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).
REV 1.2.3 4/30/02
WCR7
(MSB)
MSB
Bit 7
NV
V
WCR6
Bit 6
NV
V
WCR5
Bit 5
NV
V
WCR4
Bit 4
NV
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V
Data Registers (DR)
The 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).
WCR3
Bit 3
NV
V
WCR2
Bit 2
NV
V
Characteristics subject to change without notice.
WCR1
Bit 1
NV
V
WCR0
(LSB)
Bit 0
LSB
NV
V
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