WM8352
Production Data
11 CONTROL INTERFACE
11.1 GENERAL DESCRIPTION
The WM8352 is controlled by writing to its control registers. Readback is available for most registers.
Most aspects of the WM8352 operation can be controlled via this interface. The control interface can
operate as either a 2-, 3- or 4-wire control interface:
.
.
.
2-wire mode uses pins SCLK and SDATA.
3-wire mode uses pins CSB, SCLK and SDATA.
4-wire mode uses pins CSB, SCLK, SDATA and SDOUT.
GPIO7 is automatically enabled as CSB in 3-wire and 4-wire control modes. GPIO6 is automatically
enabled as SDOUT in 4-wire control mode. Register readback is provided on the bi-directional pin
SDATA in 2-/3-wire modes and on SDOUT (GPIO6) in 4-wire mode.
In 2-wire mode, the control interface supports single register access as well as multiple access with
or without address auto-increment.
In Development Mode (see Section 14.4), the WM8352 initially selects the secondary 2-wire control
interface, using pins GPIO10 and GPIO11. This enables configuration of the WM8352 via a separate
interface prior to selecting the normal system operation. Note that, in Custom modes, the secondary
interface is not supported.
11.2 CONTROL INTERFACE MODES
The WM8352 control interface can be configured for 2-, 3- or 4-wire operation using the following
register bits:
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R6 (06h)
Interface
Control
3
SPI_CFG
0
Controls the SDOUT (GPIO6) pin operation in
4 wire mode
0 = SDOUT output is CMOS
1 = SDOUT output is open drain
Note: SPI_4WIRE must be set for this to take
effect.
2
1
SPI_4WIRE
SPI_3WIRE
0
0
Selects 3-wire or 4-wire SPI mode
0 = 3 wire mode using bi-directional SDATA pin
1 = 4 wire mode using SDOUT (GPIO6)
Note: SPI_3WIRE must be set for this to take
effect.
Selects 2- or 3-/4-wire mode.
0 = 2-wire mode
1 = 3-/4-wire mode
Table 1 Control Interface Modes
PD, February 2011, Rev 4.4
38
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