X9252 Xicor, X9252 Datasheet - Page 18

• Manufacturer Part Number: X9252
• Description: Quad Digitally-Controlled (XDCP) potentiometer
• Manufacturer: Xicor

Move/Read Operation
The Move/Read operation simultaneously reads the
contents of a Data Register (DR) and moves the
contents into the corresponding DCP’s WCR. If the
DRs of more than one DCP are read, then the WCRs
of all those DCPs are updated with the content of their
corresponding DR. Move/Read operation consists of a
one byte, or three byte instruction followed by one or
more Data Bytes (See Figure 8). To read an arbitrary
byte, the master initiates the operation issuing the
following sequence: a START, the Slave Address byte
with the R/W bit set to “0”, an Address Byte, a second
START, and a second Slave Address byte with the R/W
bit set to “1”. After each of the three bytes, the X9252
responds with an ACK. Then the X9252 transmits Data
Figure 8. Move/Read Sequence
REV 1.4.1 7/29/03
from the
Signals
Master
Signal at
Signals from
the Slave
SDA
S
a
r
t
t
0
1
0
Setting the Current Address
Address
R/W=0
1
Slave
with
0
A
C
K
Address
Byte
C
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A
K
S
a
t
r
t
Random Address Read
0
1
Address
R/W=1
0
Slave
with
1
Bytes as long as the master responds with an ACK
during the SCL cycle following the eigth bit of each
byte. The master terminates the Move/Read operation
(issuing a STOP condition) following the last bit of the
last Data Byte.
The first byte being read is determined by the current
DCP address and by the Status Register bits,
according to Table 2 on page 15. If more than one byte
is read, the DCP address is incremented by one after
each byte, in the same way as during a Page Write
operation. After reaching DCP3, the DCP address
“rolls over” to DCP0.
On power up, the Address pointer is set to the Data
Register 0 of DCP0.
1
C
A
K
Current Address Read
First Read
Data Byte
One or more Data Bytes
A
C
K
C
A
K
Last Read
Data Byte
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