WM9713 datasheet(77/111 Pages) WOLFSON

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Preliminary Technical Data

WM9713L

PTD, March 2004, Rev 2.2

GPIO AND INTERRUPT CONTROL

The WM9713L has eight GPIO pins that operate as defined in the AC’97 Revision 2.2 specification.

Each GPIO pin can be set up as an input or as an output, and has corresponding bits in register 54h

and in slot 12. The state of a GPIO output is determined by sending data through slot 12 of outgoing

frames (SDATAOUT). Data can be returned from a GPIO input by reading the register bit, or

examining slot 12 of incoming frames (SDATAIN). GPIO inputs can be made sticky, and can be

programmed to generate an interrupt, transmitted either through the AC-Link or through a dedicated,

level-mode interrupt pin (GPIO2/IRQ, pin 45).

In addition, the GPIO pins 1, 3, 4 and 5 can be used for the PCM interface by setting bit 15 of

these pins.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

36h

PCM Codec

Control

CTRL

Enables PCM interface on GPIO pins 1, 3, 4 and

0: Normal GPIO functions

1: PCM interface enabled

56h

GPIO Pin

Sharing

8:2

GE#

1 (GPIO)

Toggle GPIO pin function:

0: secondary function enabled

1: GPIO enabled

Table 59 GPIO Additional Function Control

GPIO pins 2 to 8 are multi-purpose pins that can also be used for other (non-GPIO / -PCM)

purposes, e.g. as a SPDIF output or to signal pendown. This is controlled by register 56h.

Note that GPIO6/7/8 each have an additional function independent of the GPIO / auxillary functions

discussed above. If these pins are to be used as GPIO then the independent function needs to be

disabled using its own control registers, e.g. to use pin 11 as a GPIO then the RESETB function

needs to be disabled (RSTDIS, register 5Ah, bit 8).

Independently of the GPIO pins, the WM9713L also has seven virtual GPIOs. These are signals from

inside the WM9713L, which are treated as if they were GPIO input signals. From a software

perspective, virtual GPIOs are the same as GPIO pins, but they cannot be set up as outputs, and are

not tied to an actual pin. This allows for simple, uniform processing of different types of signals that

may generate interrupts (e.g. pen down, battery warnings, jack insertion, high-temperature warning,

or GPIO signals).

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