cat5221 Catalyst Semiconductor, cat5221 Datasheet - Page 8

• Manufacturer Part Number: cat5221
• Description: Dual Digitally Programmable Potentiometers Dpp? With 64 Taps And I?c Interface
• Manufacturer: Catalyst Semiconductor

CAT5221
INSTRUCTIONS AND REGISTER
DESCRIPTION
INSTRUCTIONS
SLAVE ADDRESS BYTE
The first byte sent to the CAT5221 from the master/
processor is called the Slave/DPP Address Byte. The
most significant four bits of the slave address are a
device type identifier. These bits for the CAT5221 are
fixed at 0101[B] (refer to Table 1).
The next four bits, A3 - A0, are the internal slave
address and must match the physical device address
which is defined by the state of the A3 - A0 input pins
for the CAT5221 to successfully continue the com–
mand sequence. Only the device which slave address
matches the incoming device address sent by the
master executes the instruction. The A3 - A0 inputs
can be actively driven by CMOS input signals or tied
to V
Table 1. Identification Byte Format
Table 2. Instruction Byte Format
Doc. No. MD-2113 Rev. K
CC
or V
SS
.
(MSB)
(MSB)
ID3
0
I3
ID2
1
I2
Device Type
Identifier
Instruction
Opcode
ID1
I1
0
ID0
I0
1
8
INSTRUCTION BYTE
The next byte sent to the CAT5221 contains the
instruction and register pointer information. The four
most significant bits used provide the instruction
opcode I [3:0]. The P0 bit points to one of the Wiper
Control Registers. The least two significant bits, R1
and R0, point to one of the four data registers of each
associated potentiometer. The format is shown in
Table 2.
Data Register Selection
A3
WCR/Pot Selection
Data Register Selected
0
A2
DR0
DR1
DR2
DR3
Slave Address
P0
A1
R1
Data Register
Characteristics subject to change without notice
Selection
R1
(LSB)
0
0
1
1
(LSB)
A0
R0
© Catalyst Semiconductor, Inc.
R0
0
1
0
1