PSD413A2 datasheet(51/123 Pages) STMICROELECTRONICS

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PSD4XX Family

9.3 I/O Ports

There are 5 programmable 8-bit I/O ports: Port A, Port B, Port C, Port D and Port E. These

ports all have multiple operating modes, depending on the configuration. Some of the basic

functions are providing input/output for the ZPLD, or can be used for standard I/O. Each

port pin is individually configurable, thus enabling a single 8-bit port to perform multiple

functions. The I/O ports occupy 256 bytes of memory space as defined by “CSIOP”. Refer

to the System Configuration section for I/O register address offset.

To set up the port configuration the user is required to:

1. Define I/O Port Chip Select (CSIOP) in the ABEL file.

2. Initialize certain port configuration registers in the user’s program and/or

3. Specify the configuration in the PSD4XX PSDsoft Software.

4. Unused input pins should be tied to VCC or GND.

The following is a description of the operating modes of the I/O ports. The functions of the

port registers are described in later sections.

9.3.1 Standard MCU I/O

The Standard MCU I/O Mode provides additional I/O capability to the microcontroller. In this

mode, the ports can perform standard I/O functions such as sensing or controlling various

external I/O devices. Operation options of this mode are as follows:

t Configuration

1. Declare pins or signals which are used as I/O in the ABEL file.

2. Set the bit or bits in the Control Register to "1".

As Output Port

– Write output data to Data Out Register

– Set Direction Register to output mode

As Input Port

– Set Direction Register to input mode

– Read input from Data In Register

The port remains an output or input port as long as the Direction Register is not changed.

9.3.2 PLD I/O

The PLD I/O mode enables the port to be configured as an input to the ZPLD, or as an

output from the GPLD macrocell. The output can be tri-stated with a control signal defined

by a product term from the ZPLD. This mode is configured by the user in the PSD4XX

PSDsoft Software, and is enabled upon power up. For a detailed description, see the

section on the ZPLD.

t Configuration

1. Declare pins or signals in the ABEL file (PSDsoft).

2. Write logic equations in the ABEL file.

3. PSD Compiler maps the PLD functions to the PSD.

The PSD4XX

Architecture

(cont.)

PSD413A2 Datasheet(PDF) 51 Page - STMicroelectronics

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