X9119 Datasheet, PDF (7/18 Pages) Xilinx, Inc – Single Digitally-Controlled (XDCP ™ ) Potentiometer

X9119
Table 3. Instruction Set
Instruction Set
Instruction
Read Wiper Counter
Register
R/W I₂ I₁ I₀ 0 RB RA 0
1 10000 0 0
0
Operation
0 Read the contents of the Wiper Counter
Register
Write Wiper Counter
Register
0 1 0 1 0 0 0 0 0 Write new value to the Wiper Counter
Register
Read Data Register
1 1 0 1 0 1/0 1/0 0 0 Read the contents of the Data Register
pointed to RB-RA.
Write Data Register
0 1 1 0 0 1/0 1/0 0 0 Write new value to the Data Register
pointed to RB-RA.
XFR Data Register to 1
Wiper Counter Register
11
0 0 1/0 1/0 0 0 Transfer the contents of the Data Register
pointed to by RB-RA.to the Wiper Counter
Register
XFR Wiper Counter
0
Register to Data Regis-
ter
11
1 0 1/0 1/0 0 0 Transfer the contents of the Wiper Counter
Register to the Data Register pointed to by
RB-RA.
Note: (1) 1/o = data is one or zero.
Instruction and Register Description
DEVICE ADDRESSING
WIPER COUNTER REGISTER (WCR)
The X9119 contains a Wiper Counter Registers (see
Table 4) for the XDCP potentiometer. The WCR is
equivalent to a serial-in, parallel-out register/counter
with its outputs decoded to select one of 1024
switches along its resistor array. The contents of the
WCR can be altered in one of three ways: (1) it may be
written directly by the host via the write wiper counter
register instruction (serial load); (2) it may be written
indirectly by transferring the contents of one of four
associated data registers via the XFR data register; (3)
it is loaded with the contents of its data register zero
(R0) upon power-up.
The Wiper Counter Register is a volatile register; that
is, its contents are lost when the X9119 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.
DATA REGISTERS (DR0 TO DR3)
The potentiometer has four 10-bit non-volatile 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 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 9–Bit 0 are used to store one of the 1024 wiper
position (0 ~1023).
7
FN8162.2
September 15, 2005