ST7261 datasheet(28/80 Pages) STMICROELECTRONICS

Part #	ST7261

Description	LOW SPEED USB 8-BIT MCU WITH 3 ENDPOINTS, ROM MEMORY, LVD, WDG, TIMER

PDF	80 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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28 / 80 page

ST7261

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I/O PORTS (Cont’d)

8.2.7 Register Description

DATA REGISTER (DR)

Port x Data Register

PxDR with x = A or B.

Read /Write

Reset Value: 0000 0000 (00h)

Bit 7:0 = D[7:0]

Data register 8 bits.

The DR register has a specific behaviour accord-

ing to the selected input/output configuration. Writ-

ing the DR register is always taken into account

even if the pin is configured as an input; this allows

to always have the expected level on the pin when

toggling to output mode. Reading the DR register

returns either the DR register latch content (pin

configured as output) or the digital value applied to

the I/O pin (pin configured as input).

DATA DIRECTION REGISTER (DDR)

Port x Data Direction Register

PxDDR with x = A or B.

Read /Write

Reset Value: 0000 0000 (00h)

Bit 7:0 = DD[7:0]

Data direction register 8 bits.

The DDR register gives the input/output direction

configuration of the pins. Each bit is set and

cleared by software.

0: Input mode

1: Output mode

DD7

DD6

DD5

DD4

DD3

DD2

DD1

DD0

ST7261 Datasheet(PDF) 28 Page - STMicroelectronics