Rainbow-electronics ATmega103L Manuel d'utilisateur télécharger pdf (Page 76)

ATmega603/103

Figure 53. Port A Schematic Diagrams (Pins PA0 - PA7)

Port B

Port B is an 8-bit bi-directional I/O port with internal pull-ups.

Three I/O memory address locations are allocated for Port B, one each for the Data Register - PORTB, $18($38), Data

Direction Register - DDRB, $17($37) and the Port B Input Pins - PINB, $16($36). The Port B Input Pins address is read

only, while the Data Register and the Data Direction Register are read/write.

All port pins have individually selectable pull-up resistors. The Port B output buffers can sink 20mA and thus drive LED dis-

plays directly. When pins PB0 to PB7 are used as inputs and are externally pulled low, they will source current if the

internal pull-up resistors are activated.

DATA BUS

RESET

MOS

PULL-

PAn

WP:

WD:

RL:

RP:

RD:

SRE:

WRITE PORTA

WRITE DDRA

READ PORTA LATCH

READ PORTA PIN

READ DDRA

EXT. SRAM ENABLE

ADDRESS

DATA

WRITE

READ

0-7

DDAn

PORTAn

SRE

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Rainbow-electronics ATmega103L Manuel d'utilisateur Page 76