PSD501B1 datasheet(46/153 Pages) STMICROELECTRONICS

46 / 153 page

PSD5XX Family

Control Register

This register is used in both Standard MCU I/O Mode and Address Out modes. For setting

a Standard MCU I/O Mode, a “1” must be written to the corresponding bit in the register.

Writing a “0” to the register is required for the Address Out mode. The register has a default

value of “0” after reset.

Direction Register

This register is used to control the direction of data flow in the I/O ports. Writing a “1” to

the corresponding bit in the register configures the port to be an output port, and a “0”

forces the port to be an input port. The I/O configuration of the port pins can be determined

by reading the Direction Register. After reset, the pins are in input mode.

Open Drain Register

This register determines whether the output pin driver of Port C or D is a CMOS driver or

an Open Drain driver. Writing a “0” to the register selects a CMOS driver, while a “1” selects

an Open Drain driver.

Special Function Register

Writing a “1” bit to this register sets up the corresponding pin to operate in Special Function

Out mode.

PLD – I/O Register

This is a read only status register. Reading a "1" indicates the corresponding pin is

configured as a PLD pin. A "0" indicates the pin is an I/O pin.

Data In Register

This register is used in the Standard MCU I/O Mode configuration to read the input pins.

Data Out Register

This register holds the output data in the Standard MCU I/O Mode. The contents of the

Macrocell Out Register

This register enables the user to read the outputs of the GPLD macrocell (PA, PB, and PE

macrocells).

I/O Register Address Offset

The I/O Register can be accessed by the microcontroller during normal read/write bus

cycles. The address of a register is defined as:

CSIOP + register address offset

The CSIOP is the base address that is defined in the ABEL file and occupies a 256 byte

space. The register address offset lies within this 256 byte space. Tables 15 and 15a are

the address offset of the registers.

I/O Ports

(Cont.)

PSD501B1 데이터시트(PDF) 46 Page - STMicroelectronics