PSD501B1-C-90UI View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

PSD501B1-C-90UI

Low Cost Field Programmable Microcontroller Peripherals

STMicroelectronics 

I/O Ports

(Cont.)

PSD5XX Family

9.3.7 Alternate Function In

This mode is per-pin configurable and enables the user to define the pins in Port E to

perform Alternate function. Alternate Function includes inputs to Counter/Timers and APD

clock.

t Configuration

1. Select input functions in PSD configuration

2. PSD compiler assigns pins for the selected function.

9.3.8 Peripheral I/O

This mode enables the microcontroller to read or write to a peripheral though Port A.

When there is no read/write operation, Port A is tri-stated. One of the applications of

Peripheral I/O is in a DMA based design.

t Configuration

1. Declare the pins used as Peripheral I/O in the ABEL file.

2. Write logic equations for PSEL0 and PSEL1.

3. Write a “1” to the PIO bit in the VM Register to activate the Peripheral I/O operation.

See the section on Peripheral I/O for a detailed description.

9.3.9 Open Drain Outputs

This mode enables the user to configure Port C and D pins as open drain outputs. CMOS

output is the default configuration. Writing “1” to the corresponding bit in the Open Drain

Register changes the pin to open drain output.

The following table summarizes the operating modes of the I/O ports. Not all functions are

available to every port.

Table 11. Operating Modes of the I/O Ports

Port Mode

Port A Port B

Standard MCU I/O

Yes

PLD I/O

Yes

Address Out

Yes

Address In

Yes

Data Port

Special Function Out

Yes

Alternate Function In

Peripheral I/O

Yes

Open Drain

Yes

Yes

Yes

Yes*

Yes

*For external decoding. Cannot be latched by ALE.

Port C

Yes

Input Only

Yes

Yes*

Yes

Port D

Yes

Input Only

Yes

Yes*

Yes

Yes

Yes

Port E

Yes

Yes

Yes

Yes*

Yes

Yes

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