Rainbow-electronics ATmega8515L Bedienungsanleitung PDF herunterladen (Seite 56)

ATmega8515(L)

2512A–AVR–04/02

I/O Ports

Introduction All AVR portshave true Read-Modify-Write functionalitywhen used as generaldigital

I/Oports.This means that the direction of one port pin can be changedwithout uninten-

tionally changing the direction of any otherpin with the SBI andCBIinstructions.The

same applieswhen changing drive value (ifconfigured as output) or enabling/disabling

ofpull-upresistors (ifconfigured as input). Each output bufferhassymmetricaldrive

characteristics withbothhighsink andsource capability.The pin driver isstrong enough

to drive LED displays directly.All port pinshave individually selectable pull-upresistors

with a supply-voltage invariant resistance. All I/Opinshave protection diodes to both

andGround as indicated in Figure 28. Refer to “ElectricalCharacteristics”onpage

194 for a complete listofparameters.

Figure 28. I/O Pin Equivalent Schematic

All registers andbit references in thissection are written in generalform. A lowercase

“x” represents the numbering letterfor the port, and a lowercase“n”represents the bit

number. However, when using the register orbit defines in a program, the precise form

must beused. For example, PORTB3 forbit no. 3 in Port B, here documented generally

as PORTxn. The physicalI/O Registers andbit locations are listed in “RegisterDescrip-

tion forI/O Ports”onpage 72.

Three I/O memory address locations areallocatedfor each port, one each for the Data

Port Input PinsI/Olocation isread only, whilethe Data Register and the Data Direction

pull-upfunction for all pins in all portswhen set.

Using the I/OportasGeneralDigitalI/O isdescribed in “Ports asGeneralDigitalI/O”on

page 57. Most port pins aremultiplexedwith alternate functionsfor the peripheralfea-

tures on the device. How each alternate function interfereswith the port pin isdescribed

in “Alternate Port Functions”onpage 61. Refer to theindividual module sectionsfor a

full description of thealternate functions.

Note that enabling thealternate function ofsome of the port pinsdoes not affecttheuse

of theotherpins in the portas generaldigitalI/O.

Logic

See Figure

"General Digital I/O" for

Details

Pxn

1 2 ... 51 52 53 54 55 56 57 58 59 60 61 ... 222 223

Keine Kommentare

Rainbow-electronics ATmega8515L Bedienungsanleitung Seite 56