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WM8803

PP Rev 1.1 September 2003

MICRO-CONTROLLER INTERFACE REGISTER OUTPUT (OPTICAL RECEIVER

MODULE POWER DOWN EXAMPLE)

This section describes an example in which UGPI outputs a micro-controller interface register, and

how that signal is used as the power supply control signal for an optical receiver module.

Connect the UGPI output to the optical receiver module power supply control switch.

After clearing a reset due to

_____

PD , the micro-controller interface register output will be selected

as the initial setting for UGPI . As a result, the GPIDAT set value will be output.

After a reset is cleared, the initial value of GPIDAT = 1, and so UGPI will be output high. The

control switch will be in the off state, and data will not be supplied from the optical receiver

module.

Setting GPIDAT = 0 will activate the optical receiver module supply data. Controlling the UGPI

output with GPIDAT will allow current drain to be minimized when the optical receiver module is

not used.

Optical receiver

module

WM8803

RXIN

UGPI

Figure 20 UGPI Output Example (Optical Receiver Module Power Supply Control)

MICRO-CONTROLLER INTERFACE REGISTER OUTPUT (DIGITAL DATA

INPUT SWITCH CONTROL SIGNAL EXAMPLE)

UGPI , when used as a micro-controller interface register output, can be used as a control signal that

switches the digital data input.

If more than one type of data input is required an input selector circuit and a control signal will be

required. It is possible to implement two digital data inputs without having to provide a control signal

from the micro-controller by using the UGPI output.

Note that after a reset is cleared, the initial value of GPIDAT will be 1, and as a result, UGPI will

output a high level.

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