W79E225A_08 Datasheet, PDF (12/203 Pages) Winbond – 8-bit Microcontroller

Preliminary W79E225A/226A/227A Data Sheet
PIN DESCRIPTION, continued
SYMBOL
TYPE
INITIAL
STATE
DESCRIPTIONS
P4.0-P4.3 I/O S H High
PORT 4: 4-bit multipurpose programmable I/O port with alternate
functions. The Port 4 has four different operation modes.
P4.0, STADC
P4.1, T2EX, IC2
P4.2
P4.3
Note: P4.2 & P4.3 are not supported in PLCC44 pins package.
P5.0-P5.1 I/O S
PORT 5: 2-bit, bit-directional I/O port. This port is not bit
addressable. The alternate functions are described below:
Tri-state ^{P5.0, PWM6}
P5.1, PWM7
Note: P5.0 & P5.1 are not supported in PLCC44 pins package.
Note jTYPE I: input, O: output, I/O: bi-directional, H: pull-high, L: pull-low, D: open drain S: Schmitt Trigger
5.1 Port 4
Port 4, SFR P4 at address A5H, is a 4-bit multipurpose programmable I/O port which functions are I/O
and chip-select function. It has four different operation modes:
z Mode 0 - P4.0 ~ P4.3 is 4-bit bi-directional I/O port which is the same as port 1. The default Port
4 is a general I/O function.
z Mode1 - P4.0 ~ P4.3 are read data strobe signals which are synchronized with RD signal at
specified addresses. These read data strobe signals can be used as chip-select signals for
external peripherals.
z Mode2 - P4.0 ~ P4.3 are write data strobe signals which are synchronized with WR signal at
specified addresses. These write data strobe signals can be used as chip-select signals for
external peripherals.
z Mode3 - P4.0 ~ P4.3 are read/write data strobe signals which are synchronized with RD
or WR signal at specified addresses. These read/write data strobe signals can be used as chip-
select signals for external peripherals.
When Port 4 is configured with the feature of chip-select signals, the chip-select signal address range
depends on the contents of the SFR P4xAH, P4xAL, P4CONA and P4CONB. P4xAH and P4xAL
contain the 16-bit base address of P4.x. P4CONA and P4CONB contain the control bits to configure
the Port 4 operation mode.
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Publication Release Date: April 15, 2008
Revision A4.0