cat5251 Catalyst Semiconductor, cat5251 Datasheet - Page 7

• Manufacturer Part Number: cat5251
• Description: Quad Digitally Programmable Potentiometer Dpp? With 256 Taps And Spi Interface
• Manufacturer: Catalyst Semiconductor

CAT5251
INSTRUCTION AND REGISTER
DESCRIPTION
DEVICE TYPE / ADDRESS BYTE
The first byte sent to the CAT5251 from the
master/processor is called the Device Address Byte.
The most significant four bits of the Device Type
address are a device type identifier. These bits for the
CAT5251 are fixed at 0101[B] (refer to Table 1).
The two least significant bits in the slave address
byte, A1 - A0, are the internal slave address and
must match the physical device address which is
defined by the state of the A1 - A0 input pins for the
CAT5251 to successfully continue the command
sequence. Only the device which slave address
matches the incoming device address sent by the
master executes the instruction. The A1 - A0 inputs
can be actively driven by CMOS input signals or tied
to V
address byte must be set to 0.
Table 1. Identification Byte Format
Table 2. Instruction Byte Format
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CC
or V
SS
. The remaining two bits in the device
(MSB)
(MSB)
ID3
I3
0
ID2
I2
1
Device Type
Identifier
Instruction
Opcode
ID1
I1
0
ID0
I0
1
7
INSTRUCTION BYTE
The next byte sent to the CAT5251 contains the
instruction and register pointer information. The four
most significant bits used provide the instruction
opcode I3-I0. The R1 and R0 bits point to one of the
four data registers of each associated potentiometer.
The least two significant bits point to one of four Wiper
Control Registers. The format is shown in Table 2.
Data Register Selection
R1
0
Data Register Selected
Data Register
Selection
R0
DR0
DR1
DR2
DR3
0
Slave Address
A1
WCR/Pot Selection
P1
R1
0
0
1
1
(LSB)
(LSB)
A0
P0
R0
Doc. No. MD-2017 Rev. F
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1
0
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