WM8321
Production Data
21 GENERAL PURPOSE INPUTS / OUTPUTS (GPIO)
21.1 GENERAL DESCRIPTION
The WM8321 has 12 general-purpose input/output (GPIO) pins, GPIO1 - GPIO12. These can be
configured as inputs or outputs, active high or active low, with optional on-chip pull-up or pull-down
resistors. GPIO outputs can either be CMOS driven or Open Drain configuration. Each GPIO pin can
be tri-stated and can also be used to trigger Interrupts.
The function of each GPIO pin is selected individually. Different voltage power domains are selectable
on a pin by pin basis for GPIOs 1-12. Input de-bounce is automatically implemented on selected
GPIO functions.
Note that, when GPIO10, GPIO11 or GPIO12 is used as an input to the AUXADC (see Section 18),
then the normal GPIO functionality cannot be supported on the affected pin(s). It is recommended
that the respective GPIO(s) are tri-stated, as described in Section 21.3.
21.2 GPIO FUNCTIONS
The list of GPIO functions supported by the WM8321 is contained in Table 52 (for input functions) and
Table 53 (for output functions). The input functions are selected when the respective GPn_DIR
register bit is 1. The output functions are selected when the respective GPn_DIR register bit is 0.
The selected function for each GPIO pin is selected by writing to the respective GPn_FN register bits.
All functions are available on all GPIO pins. The polarity of each input or output GPIO function can be
selected using the applicable GPn_POL register bit.
The available power domains for each pin are specific to different GPIOs.
The de-bounce time for the GPIO input functions is determined by the GPn_FN field. Some of the
input functions allow a choice of de-bounce times, as detailed in Table 52.
The register controls for configuring the GPIO pins are defined in Section 21.3.
GPn_FN
GPIO INPUT
FUNCTION
DESCRIPTION
DE-BOUNCE
TIME
GPIO
GPIO input. Logic level is read from the
GPn_LVL register bits. See Section 21.3.
0h
1h
2h
32s to 64s
4ms to 8ms
32ms 64ms
ON/OFF
Request
Control input for requesting an ON/OFF state
transition. See Section 11.3.
Under default polarity (GPn_POL=1), a rising
edge requests the ON state and a falling edge
requests the OFF state.
SLEEP/WAKE
Request
Control input for requesting a SLEEP/WAKE
state transition. See Section 11.3.
3h
4h
32s to 64s
32ms to 64ms
Under default polarity (GPn_POL=1), a rising
edge requests the SLEEP state and a falling
edge requests the WAKE transition to the ON
state.
SLEEP
Request
Control input for requesting a SLEEP state
transition. See Section 11.3.
5h
6h
7h
32s to 64s
32s to 64s
32s to 64s
Under default polarity (GPn_POL=1), a rising
edge requests the SLEEP state and a falling
edge has no effect.
ON Request
Control input for requesting an ON state
transition. See Section 11.3.
Under default polarity (GPn_POL=1), a rising
edge requests the ON state and a falling edge
has no effect.
Watchdog
Reset
Control input for resetting the Watchdog Timer.
See Section 25.
PD, February 2012, Rev 4.0
108
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
