ST72F324J2TCRE 데이터 시트보기 (PDF) - STMicroelectronics

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ST72F324J2TCRE

8-bit MCU for automotive, 3.8 to 5.5V operating range with 8 to 32 Kbyte Flash, 10-bit ADC, 4 timers, SPI, SCI

STMicroelectronics 

ST72324xx-Auto

9

I/O ports

I/O ports

9.1

Introduction

The I/O ports offer different functional modes:

● transfer of data through digital inputs and outputs,

and for specific pins:

● external interrupt generation,

● alternate signal input/output for the on-chip peripherals.

An I/O port contains up to eight pins. Each pin can be programmed independently as digital

input (with or without interrupt generation) or digital output.

ct(s) 9.2

Functional description

du Each port has two main registers:

ro ● Data Register (DR)

P ● Data Direction Register (DDR)

lete and one optional register:

o ● Option Register (OR)

bs Each I/O pin may be programmed using the corresponding register bits in the DDR and OR

O registers: bit X corresponding to pin X of the port. The same correspondence is used for the

- DR register.

t(s) The following description takes into account the OR register (for specific ports which do not

provide this register refer to Section 9.3: I/O port implementation on page 63). The generic

c I/O block diagram is shown in Figure 28.

rodu 9.2.1 Input modes

P The input configuration is selected by clearing the corresponding DDR register bit.

teIn this case, reading the DR register returns the digital value applied to the external I/O pin.

oleDifferent input modes can be selected by software through the OR register.

bs Note: 1 Writing the DR register modifies the latch value but does not affect the pin status.

O 2 When switching from input to output mode, the DR register has to be written first to drive the

correct level on the pin as soon as the port is configured as an output.

3 Do not use read/modify/write instructions (BSET or BRES) to modify the DR register as this

might corrupt the DR content for I/Os configured as input.

Doc ID 13841 Rev 1

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