PSD413A2 datasheet(57/123 Pages) STMICROELECTRONICS

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PSD4XX Family

9.3.10 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 A[0-7] are assigned to pins PA[0-7].

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

t Peripheral I/O

Figure 27 shows the structure of a Port A pin. If the pin is configured as an output port,

the multiplexer selects one of its three 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 through a latch latched by ALE, as Address In input.

9.3.11 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].

Figure 28 shows the structure of a Port B pin. If the pin is configured as an output port,

the multiplexer selects one of its three 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

The PSD4XX

Architecture

(cont.)

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