X9269 Datasheet, PDF (10/25 Pages) Xicor Inc. – Dual Digitally-Controlled Potentiometers

X9269
DEVICE DESCRIPTION
Instructions
Four of the nine instructions are three bytes in length.
These instructions are:
– Read Wiper Counter Register – read the current
wiper position of the selected potentiometer,
– Write Wiper Counter Register – change current
wiper position of the selected potentiometer,
– Read Data Register – read the contents of the
selected Data Register;
– Write Data Register – write a new value to the
selected Data Register.
The basic sequence of the three byte instructions is
illustrated in Figure 4. These three-byte instructions
exchange data between the WCR and one of the Data
Registers. A transfer from a Data Register to a WCR is
essentially a write to a static RAM, with the static RAM
controlling the wiper position. The response of the
wiper to this action will be delayed by t_WRL. A transfer
from the WCR (current wiper position), to a Data
Register is a write to nonvolatile memory and takes a
minimum of t_WR to complete. The transfer can occur
between one of the four potentiometers and one of its
associated registers; or it may occur globally, where the
transfer occurs between all potentiometers and one
associated register
Four instructions require a two-byte sequence to
complete. These instructions transfer data between the
host and the X9269; either between the host and one of
the data registers or directly between the host and the
Wiper Counter Register. These instructions are:
– XFR Data Register to Wiper Counter Register –
This transfers the contents of one specified Data
Register to the associated Wiper Counter Register.
– XFR Wiper Counter Register to Data Register –
This transfers the contents of the specified Wiper
Counter Register to the specified associated Data
Register.
– Global XFR Data Register to Wiper Counter
Register – This transfers the contents of all specified
Data Registers to the associated Wiper Counter Reg-
isters.
– Global XFR Wiper Counter Register to Data
Register – This transfers the contents of all Wiper
Counter Registers to the specified associated Data
Registers.
INCREMENT/DECREMENT COMMAND
The final command is Increment/Decrement (Figure 5
and 6). The Increment/Decrement command is different
from the other commands. Once the command is
issued and the X9269 has responded with an
acknowledge, the master can clock the selected wiper
up and/or down in one segment steps; thereby,
providing a fine tuning capability to the host. For each
SCL clock pulse (t_HIGH) while SDA is HIGH, the
selected wiper will move one resistor segment towards
the R_H terminal. Similarly, for each SCL clock pulse
while SDA is LOW, the selected wiper will move one
resistor segment towards the R_L terminal.
See Instruction format for more details.
REV 1.1.11 2/17/03
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Characteristics subject to change without notice. 10 of 25