X9252_14 Datasheet, PDF (15/19 Pages) Intersil Corporation – Quad Digitally-Controlled Potentiometer

X9252
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 and the WCRs of all
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 9). 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 Bytes as long as the master responds with an ACK
during the SCL cycle following the eight 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. 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.
SIGNALS
FROM THE
MASTER
S
SLAVE
T _{ADDRESS WITH}
A
R
R/W = 0
T
ADDRESS
BYTE
S
SLAVE
T _{ADDRESS WITH}
A
R
R/W = 1
T
ONE OR MORE DATA BYTES
S
A
A
C
C
K
K
T
O
P
SIGNAL AT SDA
SIGNALS FROM
THE SLAVE
01 01
0
A
C
K
01 01
A
C
K
1
A
C
K
FIRST READ
DATA BYTE
LAST READ
DATA BYTE
SETTING THE CURRENT ADDRESS
CURRENT ADDRESS READ
RANDOM ADDRESS READ
FIGURE 9. MOVE/READ SEQUENCE
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FN8167.3
July 24, 2014