Rainbow-electronics ATmega103L Bedienungsanleitung PDF herunterladen (Seite 75)

ATmega603/103

Port A Data Register - PORTA

Port A Data Direction Register - DDRA

Port A Input Pins Address - PINA

The Port A Input Pins address - PINA - is not a register, and this address enables access to the physical value on each Port

A pin. When reading PORTA the Port A Data Latch is read, and when reading PINA, the logical values present on the pins

are read.

Port A as General Digital I/O

All 8 pins in Port A have equal functionality when used as digital I/O pins.

PAn, General I/O pin: The DDAn bit in the DDRA register selects the direction of this pin, if DDAn is set (one), PAn is con-

figured as an output pin. If DDAn is cleared (zero), PAn is configured as an input pin. If PORTAn is set (one) when the pin

configured as an input pin, the MOS pull up resistor is activated. To switch the pull up resistor off, PORTAn has to be

cleared (zero) or the pin has to be configured as an output pin. The port pins are tri-stated when a reset condition becomes

active, even if the clock is not running.

Note: n: 7,6...0, pin number

Port A Schematics

Note that all port pins are synchronized. The synchronization latch is however, not shown in the figure.

Bit 76543210

$1B ($3B) PORTA7 PORTA6 PORTA5 PORTA4 PORTA3 PORTA2 PORTA1 PORTA0 PORTA

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial value00000000

Bit 76543210

$1A ($3A) DDA7 DDA6 DDA5 DDA4 DDA3 DDA2 DDA1 DDA0 DDRA

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial value00000000

Bit 76543210

$19 ($39) PINA7 PINA6 PINA5 PINA4 PINA3 PINA2 PINA1 PINA0 PINA

Read/WriteRRRRRRRR

Initial value Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z Hi-Z

Table 29. DDAn Effects on Port A Pins

DDAn PORTAn I/O Pull up Comment

0 0 Input No Tri-state (Hi-Z)

0 1 Input Yes PAn will source current if ext. pulled low.

1 0 Output No Push-Pull Zero Output

1 1 Output No Push-Pull One Output

1 2 ... 70 71 72 73 74 75 76 77 78 79 80 ... 125 126

Keine Kommentare

Rainbow-electronics ATmega103L Bedienungsanleitung Seite 75