ATMEGA640 datasheet(75/436 Pages) MICROCHIP

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ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

13.3.1

Alternate Functions of Port A

The Port A has an alternate function as the address low byte and data lines for the External Memory Interface.

Table 13-4 and Table 13-5 on page 76 relates the alternate functions of Port A to the overriding signals shown in

Figure 13-5 on page 73.

Note:

1. ADA is short for ADdress Active and represents the time when address is output. See “External Memory Interface”

on page 27 for details.

Table 13-3.

Port A Pins Alternate Functions

Port Pin

Alternate Function

PA7

AD7 (External memory interface address and data bit 7)

PA6

AD6 (External memory interface address and data bit 6)

PA5

AD5 (External memory interface address and data bit 5)

PA4

AD4 (External memory interface address and data bit 4)

PA3

AD3 (External memory interface address and data bit 3)

PA2

AD2 (External memory interface address and data bit 2)

PA1

AD1 (External memory interface address and data bit 1)

PA0

AD0 (External memory interface address and data bit 0)

Table 13-4.

Overriding Signals for Alternate Functions in PA7:PA4

Signal Name

PA7/AD7

PA6/AD6

PA5/AD5

PA4/AD4

PUOE

SRE

PUOV

~(WR | ADA(1)) •

PORTA7 • PUD

~(WR | ADA) • PORTA6

• PUD

~(WR | ADA) • PORTA5

• PUD

~(WR | ADA) • PORTA4

• PUD

DDOE

SRE

DDOV

WR | ADA

PVOE

SRE

PVOV

A7 • ADA | D7 OUTPUT

• WR

A6 • ADA | D6 OUTPUT

• WR

A5 • ADA | D5 OUTPUT

• WR

A4 • ADA | D4 OUTPUT

• WR

DIEOE

000

DIEOV

000

D7 INPUT

D6 INPUT

D5 INPUT

D4 INPUT

AIO

–

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