WM8235 Datasheet, PDF (13/154 Pages) Wolfson Microelectronics plc – 70MSPS 9-Channel AFE with Sensor Timing Generation and LVDS/CMOS Data Output

WM8235
REGISTER WRITE
Figure 4 shows sequence of operations for performing a register write. Three pins, SCK, SDI and SEN
are used for the control interface. A 16-bit address (R/W, CS0, CS1, CS2, A11 to A0) is clocked in
through SDI, MSB first, followed by an 8 –bit data word (b7 to b0), also MSB first. Setting address bit
R/W to 0 indicates that the operation is a register write. The device ID bits (CS0 and CS1) indicate
which device is being written to on a shared control bus. A register write with CS2 set to 1 writes data
to all devices on the common bus. Each bit is latched on the rising edge of SCK. When the data has
been shifted into the device, a rising edge on the SEN pin transfers the data to the appropriate internal
register.
CS2
CS1
CS0
(DSLCT2) (DSLCT1)
0
ID[1:0]
1
X
X
Table 3 Device Identification
DESCRIPTION
Indicated a device to write data
Writes data to all devices
SEN
SCK
SDI
0 CS2 CS01 CS0 A11
A2 A1 A0 B7 B6 B5
B2 B1 B0
R/W
3bit device ID
12-bit Control register address
8-bit control register data
Figure 4 Serial Interface Register Write
REGISTER READ-BACK
Figure 5 shows register read-back in serial mode. Read-back is initiated by writing to the serial bus as
described above but with address bit R/W set to 1, followed by an 8-bit dummy data word. Writing
address (A11 to A0) will cause the contents (B7 to B0) of corresponding register in the addressed
device to be output MSB first on pin SDO (on the following edge of SCK). In this mode, the CS2
register should be set to 0.
SEN
SCK
SDI
1
0 CS01 CS0 A11
SDO
Hi-Z
A2 A1 A0
X: Don’t care
X
X
X
B7 B6 B5
X
X
X
B2 B1 B0 ^Hi-Z
R/W
3bit device ID
12-bit Read back register address
8-bit outputl register data
Figure 5 Serial Interface Register Read-back
Rev 4.6
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