|
X9410 Datasheet, PDF (5/21 Pages) Xicor Inc. – Dual Digitally Controlled Potentiometer | |||
|
◁ |
X9410
Figure 3. Instruction Byte Format
Register
Select
I3 I2 I1 I0 R1 R0 0 P0
Instructions
Pot Select
The four high order bits of the instruction byte specify
the operation. The next two bits (R1 and R0) select one
of the four registers that is to be acted upon when a
register oriented instruction is issued. The last bit (P0)
selects which one of the two potentiometers is to be
affected by the instruction.
Four of the ten instructions are two bytes in length and
end with the transmission of the instruction byte. These
instructions are:
â XFR Data Register to Wiper Counter RegisterâThis
transfers the contents of one speciï¬ed Data Register
to the associated Wiper Counter Register.
â XFR Wiper Counter Register to Data RegisterâThis
transfers the contents of the speciï¬ed Wiper Counter
Register to the speciï¬ed associated Data Register.
â Global XFR Data Register to Counter RegisterâThis
transfers the contents of both speciï¬ed Data Registers
to the associated Wiper Counter Registers.
â Global XFR Wiper Counter Register to Data Registerâ
This transfers the contents of both Wiper Counter
Registers to the speciï¬ed associated Data Registers.
The basic sequence of the two byte instructions is
illustrated in Figure 4. These two-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 tWRL. A transfer
from the WCR (current wiper position), to a data register
is a write to nonvolatile memory and takes a minimum
of tWR to complete. The transfer can occur between
one of the two potentiometers and one of its associated
registers; or it may occur globally, where the transfer
occurs between both potentiometers and one
associated register.
Five instructions require a three-byte sequence to
complete. These instructions transfer data between the
host and the X9410; either between the host and one
of the data registers or directly between the host and
the Wiper Counter Register. These instructions are:
â Read Wiper Counter Registerâread the current
wiper position of the selected pot,
â Write Wiper Counter Registerâchange current wiper
position of the selected pot,
â Read Data Registerâread the contents of the
selected data register;
â Write Data Registerâwrite a new value to the
selected data register.
â Read StatusâThis command returns the contents of
the WIP bit which indicates if the internal write cycle
is in progress.
The sequence of these operations is shown in Figure 5
and Figure 6.
The ï¬nal command is Increment/Decrement. It is
different from the other commands because itâs length
is indeterminate. Once the command is issued, the
master can clock the selected wiper up and/or down in
one resistor segment steps, thereby providing a ï¬ne
tuning capability to the host. For each SCK clock pulse
(tHIGH) while SI is HIGH, the selected wiper will move
one resistor segment towards the VH/RH terminal.
Similarly, for each SCK clock pulse while SI is LOW, the
selected wiper will move one resistor segment towards
the VL/RL terminal. A detailed illustration of the
sequence and timing for this operation are shown in
Figures 7-8.
REV 1.1 10/6/00
www.xicor.com
Characteristics subject to change without notice. 5 of 21
|
▷ |