X9119_08 Datasheet, PDF (6/17 Pages) Intersil Corporation – Single Digitally-Controlled (XDCP™) Potentiometer

X9119
Instruction and Register Description
Device Addressing: Identification Byte (ID and A)
Following a start condition, the master must output the
address of the slave it is accessing. The most significant four
bits of the slave address are the device type identifier. The
ID[3:0] bits is the device id for the X9119; this is fixed as
0101[B] (refer to Table 1).
The A2–A0 bits in the ID byte is the internal slave address.
The physical device address is defined by the state of the
A2–A0 input pins. The slave address is externally specified
by the user. The X9119 compares the serial data stream with
the address input state; a successful compare of both
address bits is required for the X9119 to successfully
continue the command sequence. Only the device which
TABLE 1. IDENTIFICATION BYTE FORMAT
DEVICE TYPE
IDENTIFIES
ID3
ID2
ID1
ID0
0
1
0
1
(MSB)
slave address matches the incoming device address sent by
the master executes the instruction. The A2–A0 inputs can
be actively driven by CMOS input signals or tied to V_CC or
V_SS. The R/W bit is the LSB and is be used to program the
device for read or write operations.
INSTRUCTION BYTE AND REGISTER SELECTION
The next byte sent to the X9119 contains the instruction and
register pointer information. The three most significant bits
are used provide the instruction opcode (IOP[2:0]). The RB
and RA bits point to one of the four registers. The format is
shown below in Table 2.
Table 3 provides a complete summary of the instruction set
opcodes.
INTERNAL SLAVE
ADDRESS
A2
A1
A0
READ OR
WRITE BIT
R/W
(LSB)
TABLE 2. INSTRUCTION BYTE FORMAT
INSTRUCTION
OPCODE
REGISTER
SELECTION
I2
I1
I0
0
RB
RA
0
0
(MSB)
(LSB)
REGISTER SELECTED
RB
RA
DR0
0
0
DR1
0
1
DR2
1
0
DR3
1
1
TABLE 3. INSTRUCTION SET
INSTRUCTION SET
INSTRUCTION
Read Wiper Counter
Register
R/W I₂ I₁ I₀ 0 RB RA 0 0
OPERATION
1
10000
0
0 0 Read the contents of the Wiper Counter
Register
Write Wiper Counter
Register
0
10100
0
0 0 Write new value to the Wiper Counter
Register
Read Data Register
1
1 0 1 0 1/0 1/0 0 0 Read the contents of the Data Register pointed to
RB-RA.
Write Data Register
0
1 1 0 0 1/0 1/0 0 0 Write new value to the Data Register
pointed to RB-RA.
XFR Data Register to
Wiper Counter Register
1
1 1 0 0 1/0 1/0 0 0 Transfer the contents of the Data Register
pointed to by RB-RA.to the Wiper Counter
Register
XFR Wiper Counter Register 0
to Data Register
1 1 1 0 1/0 1/0 0 0 Transfer the contents of the Wiper Counter
Register to the Data Register pointed to by
RB-RA.
NOTE: 1/0 = data is one or zero.
6
FN8162.4
July 9, 2008