WM8993 datasheet(108/229 Pages) WOLFSON

108 / 229 page

WM8993

Production Data

PD, November 2010, Rev 4.0

108

The de-bounce function on the GPIO functions enable transient behaviour to be filtered as illustrated

below:

Figure 35 GPIO De-bounce

GPIO SUMMARY

Details of the GPIO implementation are shown below. When the GPIO pad is configured as an

output, the corresponding input is disabled, as shown in Figure 36 below. This avoids an unstable

loop condition.

Figure 36 GPIO Pad

The GPIO register, i.e. latch structure, is shown in Figure 37 below. The illustration describes the

GPIO1 functionality; the equivalent logic applies to the other GPIO functions also (eg. FLL_LOCK,

TEMPOK, Jack Detect).

In the example illustrated, the de-bounce control field GPIO1_DB determines whether the signal is

de-bounced or not. (Note that TOCLK needs to be present in order for the de-bounce circuit to work.)

The polarity bit GPIO1_POL controls whether an interrupt is triggered by a logic 1 level (for

GPIO1_POL = 0) or a logic 0 level (for GPIO1_POL = 1). The latch will cause the interrupt to be

stored until it is reset by writing to the Interrupt Register. The latched signal is passed to the IRQ

circuit, shown in Figure 38. The interrupt status bits can be read at any time from Register R18 (12h).

The interrupt status bits are reset by writing a logic 1 to the respective bit in Register R18 (12h).

Figure 37 GPIO Function

WM8993 Datasheet(PDF) 108 Page - Wolfson Microelectronics plc