psd511b1 STMicroelectronics, psd511b1 Datasheet - Page 42

• Manufacturer Part Number: psd511b1
• Description: Low Cost Field Programmable Microcontroller Peripherals
• Manufacturer: STMicroelectronics

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, the Counter/Timer, 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 PSD5XX PSDsoft Software.
4. Unused input pins should be tied to V
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:
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 PSD5XX
PSDsoft Software, and is enabled upon power up. For a detailed description, see the
section on the ZPLD.
Configuration
1. Declare pins or signals which are used as I/O in the ABEL file (PSDsoft).
2. Set the bit or bits in the Control Register to "1".
3. As Output Port
– Write output data to Data Out Register
– Set Direction Register to output mode
4. As Input Port
– Set Direction Register to input mode
– Read input from Data In Register
Configuration
1. Declare pins or signals in the ABEL file (PSDsoft)
2. Write logic equations in the ABEL file.
3. PSDcompiler maps the PLD function to the PSD.
CC
or GND.
PSD5XX Family
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