X9111 Xicor, X9111 Datasheet - Page 6

• Manufacturer Part Number: X9111
• Description: Single Digitally-Controlled Potentiometer
• Manufacturer: Xicor

Table 4. Identification Byte Format
Table 5. Instruction Byte Format
DEVICE INSTRUCTIONS
Identification Byte (ID and A)
The first byte sent to the X9111 from the host, following
a CS going HIGH to LOW, is called the Identification
Byte. The most significant four bits of the slave address
are a device type identifier. The ID[3:0] bits is the
device ID for the X9111; this is fixed as 0101[B] (refer
to Table 4).
The A1–A0 bits in the ID byte are the internal slave
address. The physical device address is defined by the
state of the A1–A0 input pins. The slave address is
externally specified by the user. The X9111 compares
the serial data stream with the address input state; a
X9111 – Preliminary Information
Table 1. Wiper Latch, WL (10-bit), WCR9–WCR0: Used to store the current wiper position (Volatile, V)
Table 2. Data Register, DR (10-bit), Bit 9–Bit 0: Used to store wiper positions or data (Non-Volatile, NV)
Table 3. Status Register, SR (1-bit)
REV 1.1.15 5/9/03
WCR9
(MSB)
(LSB)
MSB
WIP
Bit 9
(MSB)
(MSB)
NV
V
ID3
I2
0
WCR8
Bit 8
NV
V
Instruction
Opcode
ID2
I1
1
Device Type
Identifier
WCR7
Bit 7
NV
V
ID1
I0
0
WCR6
Bit 6
NV
V
ID0
WCR5
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1
0
Bit 5
NV
V
successful compare of the address bits is required for
the X9111 to successfully continue the command
sequence. Only the device whose 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
or V
read or write mode.
Instruction Byte and Register Selection
The next byte sent to the X9111 contains the
instruction and register pointer information. The three
most significant bits are used provide the instruction
opcode (I[2:0]). The RB and RA bits point to one of the
four registers. The format is shown in Table 5.
WCR4
RB
0
0
1
1
Bit 4
NV
V
RB
0
SS
. The R/W bit is used to set the device to either
RA
Selection
Register
0
1
0
1
WCR3
Bit 3
NV
V
Register
DR0
DR1
DR2
DR3
RA
A1
Characteristics subject to change without notice.
Internal Slave
Address
WCR2
Bit 2
NV
V
A0
0
WCR1
Bit 1
NV
V
Read or
Write Bit
(LSB)
(LSB)
R/W
WCR0
(LSB)
0
Bit 0
LSB
NV
V
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