CAT5409_13 Datasheet, PDF (10/15 Pages) ON Semiconductor – Quad Digital Potentiometer (POT)

CAT5409
 Read Data Register – read the contents of the selected
Data Register
 Write Data Register – write a new value to the
selected Data Register
Table 12. INSTRUCTION SET (Note: 1/0 = data is one or zero)
Instruction Set
Instruction
I3 I2 I1 I0 R1 R0 WCR1/ P1
Read Wiper
10010 0
1/0
Control Register
Write Wiper Control 1 0 1 0 0 0
1/0
Register
Read Data
Register
1 0 1 1 1/0 1/0
1/0
Write Data Register 1 1 0 0 1/0 1/0
1/0
XFR Data Register 1 1 0 1 1/0 1/0
1/0
to Wiper Control
Register
XFR Wiper Control 1 1 1 0 1/0 1/0
1/0
Register to Data
Register
Gang XFR Data
0 0 0 1 1/0 1/0
0
Registers to Wiper
Control Registers
Gang XFR Wiper
1 0 0 0 1/0 1/0
0
Control Registers
to Data Register
Increment/
00100 0
1/0
Decrement Wiper
Control Register
WCR0/ P0
1/0
1/0
1/0
1/0
1/0
1/0
0
0
1/0
Operation
Read the contents of the Wiper Control
Register pointed to by P1−P0
Write new value to the Wiper Control
Register pointed to by P1−P0
Read the contents of the Data Register
pointed to by P1−P0 and R1−R0
Write new value to the Data Register
pointed to by P1−P0 and R1−R0
Transfer the contents of the Data
Register pointed to by P1−P0 and
R1−R0 to its associated Wiper Control
Register
Transfer the contents of the Wiper
Control Register pointed to by P1−P0 to
the Data Register pointed to by R1−R0
Transfer the contents of the Data
Registers pointed to by R1−R0 of all four
pots to their respective Wiper Control
Registers
Transfer the contents of both Wiper
Control Registers to their respective data
Registers pointed to by R1−R0 of all four
pots
Enable Increment/decrement of the
Control Latch pointed to by P1−P0
The basic sequence of the three byte instructions is
illustrated in Figure 11. These three-byte instructions
exchange data between the WCR and one of the Data
Registers. The WCR controls the position of the wiper. 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 non-volatile 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 the transfer can occur between all
potentiometers and one associated register.
Four instructions require a two-byte sequence to
complete, as illustrated in Figure 10. These instructions
transfer data between the host/processor and the CAT5409;
either between the host and one of the data registers or
directly between the host and the Wiper Control Register.
These instructions are:
 XFR Data Register to Wiper Control Register
This transfers the contents of one specified Data
Register to the associated Wiper Control Register.
 XFR Wiper Control Register to Data Register
This transfers the contents of the specified Wiper
Control Register to the specified associated Data
Register.
 Global XFR Data Register to Wiper Control
Register
This transfers the contents of all specified Data
Registers to the associated Wiper Control Registers.
 Global XFR Wiper Counter Register to Data
Register
This transfers the contents of all Wiper Control
Registers to the specified associated Data Registers.
Increment/Decrement Command
The final command is Increment/Decrement (Figures 6
and 12). The Increment/Decrement command is different
from the other commands. Once the command is issued and
the CAT5409 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 Instructions format for more detail.
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