CAT5259 Datasheet, PDF (10/16 Pages) Catalyst Semiconductor – Quad Digitally Programmable Potentiometers (DPP) with 256 Taps and 2-wire Interface

CAT5259
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_WR. 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 7. These instructions
transfer data between the host/processor and the
CAT5259; 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
DataRegister 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.
Figure 7. Two-Byte Instruction Sequence
— Gang XFR Data Register to Wiper Control
Register
This transfers the contents of all specified Data
Registers to the associated Wiper Control
Registers.
— Gang 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 (Figure 9
and 10). The Increment/Decrement command is
different from the other commands. Once the
command is issued and the CAT5259 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 RL terminal.
See Instructions format for more detail.
SDA
0101
S ^{ID3 ID2 ID1 ID0} A3 A2 A1 A0 A I3 I2 I1 I0 R1 R0 P1 P0 A ^S
T
C
CT
A
R
T
Device ID
Internal
Address
K
Instruction
Opcode
KO
Register Pot/WCR ^P
Address Address
Figure 8. Three-Byte Instruction Sequence
SDA
0 101
S
T
ID3 ID2 ID1 ID0 A3
A
R Device ID
T
A2 A1 A0
Internal
Address
A I3
C
K
I2 I1 I0
Instruction
Opcode
R1 R0 P1 P0 A
C
K
Data Pot/WCR
Register Address
Address
D7 D6 D5 D4 D3 D2 D1 D0 A S
CT
WCR[7:0]
KO
P
or
Data Register D[7:0]
Figure 9. Increment/Decrement Instruction Sequence
SDA
0101
S ^{ID3 ID2 ID1 ID0 A3 A2 A1 A0} A ^{I3 I2 I1 I0 R1 R0 P1 P0} A I I
T
A Device ID
Internal
C
CN N
K
Instruction Data Pot/WCR K C C
R
Address
Opcode
Register ^Address
12
T
Address
ID
NE
CC
n1
DS
ET
CO
nP
Doc. No. MD-2000 Rev. J
10
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Characteristics subject to change without notice