WM8991 Datasheet, PDF (94/174 Pages) Wolfson Microelectronics plc – Mobile Multimedia CODEC with Dual-Mode Class AB/D Speaker Driver

WM8991
Pre-Production
INTERRUPT EVENT OUTPUT
An interrupt can be generated by any of the following events described earlier:
• Button Control input (on GPIO1 to GPIO6, 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 55. 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 WM8991, the following
register settings are required:
• ALRCGPIO1 = 1 (only required if using GPIO1)
• MCLK_SRC = 0 (only required if using GPIO2)
• AIF_SEL = 0 (only required if using GPIO3, GPIO4 or GPIO5)
• ALRCGPIO6 = 0 (only required if using GPIO6)
• 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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PP, May 2008, Rev 3.1
94