WM8959 datasheet(82/155 Pages) WOLFSON

82 / 155 page

WM8959

Pre-Production

PP, May 2008, Rev 3.1

INTERRUPT EVENT OUTPUT

An interrupt can be generated by any of the following events described earlier:

•

Button Control input (on GPIO1, GPIO3 to GPIO5, GPI7 and GPI8)

•

MICBIAS current / short circuit / accessory detect

•

PLL Lock

•

Temperature Sensor

The interrupt status flag IRQ is asserted when any un-masked Interrupt input is asserted. It is the

OR’d combination of all the un-masked Interrupt inputs. If required, this flag may be inverted using

the IRQ_INV register bit. The GPIO pins can be configured to output the IRQ signal.

The interrupt behaviour is driven by level detection (not edge detection) of the un-masked inputs.

Therefore, if an input remains asserted after the interrupt register has been reset, then the interrupt

status flag IRQ will be triggered again even though no transition has occurred. If edge detection is

required (eg. confirming that the input has been de-asserted), then the polarity inversion may be

used after each event in order to detect each rising and falling edge separately. This is described

further in the “GPIO Summary” section.

The status of the IRQ flag may be read back via the control interface. The status of each GPIO pin

and the internal signals PLL_LCK, TEMPOK, MICSHRT and MICDET may also be read back in the

same way.

The IRQ register (R18) is described in Table 47. The status of the GPIO pins or other Interrupt inputs

can be read back via the read/write bits R18[11:0]. The Interrupt inputs are latched once set. Each

input may be reset by writing a 1 to the appropriate bit. The IRQ bit cannot be reset; it is the OR’d

combination of all other registers and will reset only if R18[11:0] are all 0.

If direct output of the Interrupt signal is required to external pins of the WM8959, the following

•

GPIO1_ENA = 1 (only required if using GPIO1)

•

AIF_SEL = 0 (only required if using GPIO3, GPIO4 or GPIO5)

•

AIF_TRIS = 0

•

GPIOn_SEL = 0111 for the selected Interrupt (IRQ) output pin

•

GPIOn_PU = 0 for the selected Interrupt (IRQ) output pin

•

GPIOn_PD = 0 for the selected Interrupt (IRQ) output pin

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