Direction Control; Operation; Data Transfer - Fujitsu MB86R02 Jade-D Hardware Manual

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MB86R02 'Jade-D' Hardware Manual V1.64

This section describes the operation of the GPIO module.

24.7.1 Direction control

The direction of the GPIO ports (bits 23 – 0) can be changed using the GPDDRx register. The

initial direction (the DDRx bit's initial value in the GPDDRx register) after reset is "0" (output port).

Be careful to avoid a bus conflict when changing a GPIO port's direction.

When a GPIO port is used as an input port (DDRx = 0), the data signal input to the port input

signal (PI) is stored in PDRx (in) on the rising edge of the APB clock (see Figure 13-1). Input

data can be read via the GPDRx register. During the period, write access to the GPDRx register

is valid and PDRx (out) is changeable except when DDRx = 0.

When the GPIO port is used as an output port (DDR = 1), the GPDRx register value is output to

the port output signal (PO); during which the read data of the register assumes the same value

as the port output signal's value.