WM8940
Pre-Production
Figure 33 Example Usage of MODE Pin to Generate a Clock out in 3-wire Mode
This example shows how the MODE_GPIO register bit interfaces to the MODE pad in the case
there MODE is used as a GPIO output. When MODE_GPIO is set, the internal version of
MODE is overridden to high and the MODE pin output driver is enabled. The pull up, which is
used to default 3-wire mode at start-up, is disabled as a power saving measure. MODE_GPIO
cannot be set in 2-wire m–de - this would prevent correct operation of the control interface.
Internal timing is arranged to ensure that the override is in place before the pull-up is disabled.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R8
7
MODE_GPIO
0
Selects MODE as a GPIO pin
GPIO
0 = MODE is an input. MODE selects 2-
wire mode when low and 3-wire mode
when high.
control
1 = MODE can be an input or output
under the control of the GPIO control
register. Interface operates in 3-wire
mode regardless of what happens on the
MODE pin.
Table 54 Mode is GPIO Control
Auto-incremental writes are supported in 2 wire and 3 wire modes. This is enabled by default.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R9
1
AUTOINC
1
Auto-Incremental write enable
0=Auto-Incremental writes disabled
Control
Interface
1=Auto-Incremental writes enabled
Table 55 Control Interface
Pre-Production, Rev 3.0, February 2007
60
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
