X9111
Five of the seven instructions are four bytes in length. These
instructions are:
•
Read Wiper Counter Register
– read the current wiper
position of the selected pot,
•
Write Wiper Counter Register
– change current wiper
position of the selected pot,
•
Read Data Register
– read the contents of the selected
data register;
•
Write Data Register
– write a new value to the selected
data register.
•
Read Status
– This command returns the contents of the
WIP bit which indicates if the internal write cycle is in
progress.
The basic sequence of the four byte instructions is illustrated
in Figure 3. These four-byte instructions exchange data
between the WCR and one of the Data Registers. A transfer
from a Data Register to a WCR is essentially a write to a
static RAM, with the static RAM controlling the wiper
position. The response of the wiper to this action will be
delayed by tWRL. A transfer from the WCR (current wiper
position), to a Data Register is a write to nonvolatile memory
and takes a minimum of tWR to complete. The transfer can
occur between the potentiometer and one of its associated
registers. The Read Status Register instruction is the only
unique format (see Figure 4).
Two instructions require a two-byte sequence to complete
(see Figure 2). These instructions transfer data between the
host and the X9111; either between the host and one of the
Data Registers or directly between the host and the Wiper
Counter Register. These instructions are:
•
XFR Data Register to Wiper Counter Register
– This
transfers the contents of one specified Data Register to
the associated Wiper Counter Register.
•
XFR Wiper Counter Register to Data Register
– This
transfers the contents of the specified Wiper Counter
Register to the specified associated Data Register.
See Instruction format for more details.
Write in Process (WIP bit)
The contents of the Data Registers are saved to nonvolatile
memory when the CS pin goes from LOW to HIGH after a
complete write sequence is received by the device. The
progress of this internal write operation can be monitored by
a Write In Process bit (WIP). The WIP bit is read with a Read
Status command (see Figure 4).
Power Up and Down Requirements
There are no restrictions on the power-up condition of V
CC
and the voltages applied to the potentiometer pins provided
that the V
CC
is always more positive than or equal to the
voltages at R
H
, R
L
, and R
W
, i.e., V
CC
≥
R
H
, R
L
, R
W
. There
are no restrictions on the power-down condition. However,
the datasheet parameters for the DCP do not apply until
1millisecond after V
CC
reaches its final value.
CS
SCK
SI
0
ID3
1
ID2
0
ID1
1
ID0
0
0
A1
A0
R/W
I2
I1
I0
0
0
RB
RA
0
0
0
Device ID
Internal
Address
Instruction
Opcode
Register
Address
FIGURE 2. TWO-BYTE INSTRUCTION SEQUENCE
CS
SCK
SI
0
1
0
1
0
0
A1 A0 R/W I2 I1
0
X
X
0
0 X
X
X X
X X
W
C
R
9
W
C
R
8
W
C
R
7
W
C
R
6
W
C
R
5
W
C
R
4
W
C
R
3
W
C
R
2
W
C
R
1
W
C
R
0
ID3 ID2 ID1 ID0 0
Device ID
I0 0 RB RA 0 0
Register
Address
Internal
Address
Instruction
Opcode
Wiper
Position
FIGURE 3. FOUR-BYTE INSTRUCTION SEQUENCE (WRITE OR READ FOR WCR OR DATA REGISTERS)
6
FN8159.4
September 15, 2006
INTERSIL [ INTERSIL CORPORATION ]
