PSD511B1 datasheet(48/153 Pages) STMICROELECTRONICS

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PSD5XX Family

9.3.11 Port A – Functionality and Structure

Port A is the most flexible of all the I/O ports. It can be configured to perform one or more

of the following functions:

t Standard MCU I/O Mode

t PLD I/O

t Address Out – latched address lines assigned to pins PA[0-7]

t Address In – input port for other lines, inputs can be latched by ALE.

t Special Function Out – pins PA0 – PA3 can be configured as dedicated timer outputs.

t Peripheral I/O

Figure 21 shows the structure of a Port A pin. If the pin is configured as an output port, the

multiplexer selects one of its four inputs as output. If the pin is configured as an input, the

input connects to :

1. Data In Register as input in Standard MCU I/O Mode

2. PA Macrocell as PLD input

3. PA Macrocell as Address In input (latched for multiplexed bus).

9.3.12 Port B – Functionality and Structure

Port B is similar to Port A in structure. It can be configured to perform one or more of the

following functions:

t Standard MCU I/O Mode

t PLD I/O

t Address Out – address lines A[0-7] for 8-bit multiplexed bus, or address lines

A[8-15] for 16-bit multiplexed bus are assigned to pins PB[0-7].

t Special Function Out – pins PB0 - PB3 are configured as dedicated Timer outputs.

Figure 22 shows the structure of a Port B pin. If the pin is configured as an output port, the

multiplexer selects one of its four inputs as output. If the pin is configured as input, the input

connects to :

t Data In Register as input in Standard MCU I/O Mode

t PB Macrocell as PLD input

I/O Ports

(Cont.)

PSD511B1 Datasheet(PDF) 48 Page - STMicroelectronics