ATmega128 datasheet(73/386 Pages) ATMEL

73 / 386 page

2467S–AVR–07/09

ATmega128

Special Function IO

• Bit 2 – PUD: Pull-up disable

When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn and

PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01). See “Con-

figuring the Pin” on page 67 for more details about this feature.

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 28 and Table 29 relates the alternate functions of Port A to the overriding signals shown in

Figure 33 on page 71.

Note:

1. ADA is short for ADdress Active and represents the time when address is output. See “Exter-

nal Memory Interface” on page 26 for details.

Bit

TSM

–

ACME

PUD

PSR0

PSR321

SFIOR

Read/Write

R/W

Initial Value

Table 27. 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 28. 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

DIEOV

D7 INPUTD6 INPUTD5 INPUTD4 INPUT

AIO

–

ATmega128 Datenblatt(PDF) 73 Page - ATMEL Corporation

ATmega128 Datenblatt(HTML) 73 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datenblatt Download

Link URL