AT43USB325 datasheet(60/109 Pages) ATMEL

60 / 109 page

3355C–USB–4/05

AT43USB325

7.4.4

Port D as General Digital I/O

PDn, General I/O Pin: The DDDn bit in the DDRD register selects the direction of this pin. If

DDDn is set (one), PDn is con-figured as an output pin. If DDDn is cleared (zero), PDn is config-

ured as an input pin. The value of PORTDn has no meaning in this mode. The Port D pins are

tri-stated when a reset condition becomes active.

Note:

n: 7,6,5,4,3,1,0, pin number

7.4.5

Alternate Functions of Port D

INT1, External Interrupt Source 1: The PD3 pin can serve as an external interrupt source to

the MCU. See the interrupt description for further details, and how to enable the source.

7.5

Port E

Port E[0:3] each is a bi-directional I/O port with open drain outputs and controlled slew rate and

is designed for use as the column drivers in a keyboard controller. The Port E[0:3] output buffers

can sink 4 mA. Port E[4:7] are bi-directional I/O with outputs capable of driving LEDs directly.

Each pin of Port E[4:7] has a series resistor to limit the LEDs current.

Three I/O memory address locations are allocated for the Port E, one each for the Data Register

- PORTE, $03($23), Data Direction Register - DDRE, $02($22) and the Port E Input Pins - PINE,

$01($21). The Port E Input Pins address is read only, while the Data Register and the Data

Direction Register are read/write.

7.5.1

Port E Data Register – PORTE

7.5.2

Port E Data Direction Register – DDRE

Table 7-3.

DDDn Bits on Port D Pins

DDDn

PORTDn

I/O

Comment

Input

Tri-state (Hi-Z)

Input

Tri-state (Hi-Z)

Output

Push-pull Zero Output

Output

Push-pull One Output

Bit

$03($23)

PORTE7

PORTE6

PORTE5

PORTE4

PORTE3

PORTE2

PORTE1

PORTE0

PORTE

Read/Write

R/W

Initial Value

Bit

$02 ($22)

DDE7

DDE6

DDE5

DDE4

DDE3

DDE2

DDE1

DDE0

DDRE

Read/Write

R/W

Initial Value

AT43USB325 Datasheet(PDF) 60 Page - ATMEL Corporation

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