ATMEGA64-16AI datasheet(72/393 Pages) ATMEL

72 / 393 page

ATmega64(L)

2490L–AVR–10/06

The following subsections shortly describe the alternate functions for each port, and

relate the overriding signals to the alternate function. Refer to the alternate function

description for further details.

SFIOR – 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 “Configuring the Pin” on page 67 for more details about this feature.

Table 26. Generic Description of Overriding Signals for Alternate Functions

Signal

Name

Full Name

Description

PUOE

Pull-up Override

Enable

If this signal is set, the pull-up enable is controlled by the

PUOV signal. If this signal is cleared, the pull-up is enabled

when {DDxn, PORTxn, PUD} = 0b010.

PUOV

Pull-up Override

Value

If PUOE is set, the pull-up is enabled/disabled when PUOV

is set/cleared, regardless of the setting of the DDxn,

PORTxn, and PUD Register bits.

DDOE

Data Direction

Override Enable

If this signal is set, the Output Driver Enable is controlled by

the DDOV signal. If this signal is cleared, the Output driver is

enabled by the DDxn Register bit.

DDOV

Data Direction

Override Value

If DDOE is set, the Output Driver is enabled/disabled when

DDOV is set/cleared, regardless of the setting of the DDxn

PVOE

Port Value Override

Enable

If this signal is set and the Output Driver is enabled, the port

value is controlled by the PVOV signal. If PVOE is cleared,

and the Output Driver is enabled, the port Value is controlled

by the PORTxn Register bit.

PVOV

Port Value Override

Value

If PVOE is set, the port value is set to PVOV, regardless of

the setting of the PORTxn Register bit.

DIEOE

Digital Input Enable

Override Enable

If this bit is set, the Digital Input Enable is controlled by the

DIEOV signal. If this signal is cleared, the Digital Input

Enable is determined by MCU state (Normal mode, sleep

modes).

DIEOV

Digital Input Enable

Override Value

If DIEOE is set, the Digital Input is enabled/disabled when

DIEOV is set/cleared, regardless of the MCU state (Normal

mode, sleep modes).

Digital Input

This is the Digital Input to alternate functions. In the figure,

the signal is connected to the output of the Schmitt Trigger

but before the synchronizer. Unless the Digital Input is used

as a clock source, the module with the alternate function will

use its own synchronizer.

AIO

Analog Input/output

This is the Analog Input/output to/from alternate functions.

The signal is connected directly to the pad, and can be used

bi-directionally.

Bit

0x20 (0x40)

TSM

–

ACME

PUD

PSR0

PSR321

SFIOR

Read/Write

R/W

Initial Value

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