WM8990ECS/RV Wolfson Microelectronics, WM8990ECS/RV Datasheet - Page 88

• Manufacturer Part Number: WM8990ECS/RV
• Description: Audio CODECs Stereo CODEC w.Class AB/D speaker driver
• Manufacturer: Wolfson Microelectronics

Specifications of WM8990ECS/RV

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8990
w
BUTTON CONTROL
The WM8990 GPIO supports button control detection with full status readback for up to seven inputs
(and one IRQ output). All inputs are latched at the IRQ Register, with de-bounce available for normal
operation. De-bouncing may be disabled in order to allow the device to respond to wake-up events
while the processor is disabled and is unable to provide a clock for de-bouncing.
To enable button control and accessory detection, the following register settings are required:
Programmable pull-up and pull-down resistors are available on GPIO1 and GPIO3 to GPIO5. These
should be set according to the external circuit configuration. Note that pull-up and pull-down resistors
are not available on the GPI7 and GPI8 input pins. Note that the analogue input paths to GPI7 and
GPI8 must be disabled as described above when using these as digital inputs.
In this application, one or more of the GPIO pins may be configured as an Interrupt event if desired.
This is controlled by the GPIOn_IRQ_ENA bits described in Table 46. The GPIO Pin status fields
contained in the IRQ Register (R18) may be read at any time or else in response to an Interrupt
event. See Table 55 for more details of the Interrupt function.
An example configuration of the button control GPIO function is illustrated in Figure 43.
Figure 43 Example of Button Control Using GPIO Pins
Note:
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ALRCGPIO1 = 1 (only required if using GPIO1)
AIF_SEL = 0 (only required if using GPIO3, GPIO4 or GPIO5)
LMN3 = 0, LLI3LO = 0 and RLI3LO = 0 (only required if using GPI7)
RMN3 = 0, RRI3LO = 0 and RI3RO = 0 (only required if using GPI8)
AIF_TRIS = 0
GPIOn_SEL = 0000 for each required GPIO button input
The GPIOs 1 and 3 to 5 are referenced to DBVDD
The GPIs 7 and 8 are referenced to AVDD
PD, March 2009, Rev 4.0
Production Data
88