ATmega644PA datasheet(298/468 Pages) ATMEL

298 / 468 page

298

8152G–AVR–11/09

ATmega164PA/324PA/644PA/1284P

Note:

1. The SPIEN Fuse is not accessible in serial programming mode.

2. The default value of BOOTSZ1..0 results in maximum Boot Size. See Table 25-10 on page

291 for details.

3. See ”WDTCSR – Watchdog Timer Control Register” on page 60 for details.

4. Never ship a product with the OCDEN Fuse programmed regardless of the setting of Lock bits

and JTAGEN Fuse. A programmed OCDEN Fuse enables some parts of the clock system to

be running in all sleep modes. This may increase the power consumption.

Note:

1. The default value of SUT1..0 results in maximum start-up time for the default clock source.

See ”System and Reset Characteristics” on page 334 for details.

2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 8 MHz. See Table 8-1 on

page 31 for details.

3. The CKOUT Fuse allow the system clock to be output on PORTB1. See ”Clock Output Buffer”

on page 39 for details.

4. See ”System Clock Prescaler” on page 39 for details.

The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if

Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits.

Table 26-4.

Fuse High Byte

Bit No

Description

Default Value

OCDEN(4)

7Enable OCD

1 (unprogrammed, OCD

disabled)

JTAGEN

Enable JTAG

0 (programmed, JTAG enabled)

SPIEN(1)

Enable Serial Program and Data

Downloading

0 (programmed, SPI prog.

enabled)

WDTON(3)

Watchdog Timer always on

1 (unprogrammed)

EESAVE

EEPROM memory is preserved

through the Chip Erase

1 (unprogrammed, EEPROM

not preserved)

BOOTSZ1

Select Boot Size (see Table 26-9 for

details)

0 (programmed)(2)

BOOTSZ0

Select Boot Size (see Table 26-9 for

details)

0 (programmed)(2)

BOOTRST

Select Reset Vector

1 (unprogrammed)

Table 26-5.

Fuse Low Byte

Bit No

Description

Default Value

CKDIV8(4)

Divide clock by 8

0 (programmed)

CKOUT(3)

Clock output

1 (unprogrammed)

SUT1

Select start-up time

1 (unprogrammed)(1)

SUT0

Select start-up time

0 (programmed)(1)

CKSEL3

Select Clock source

0 (programmed)(2)

CKSEL2

Select Clock source

0 (programmed)(2)

CKSEL1

Select Clock source

1 (unprogrammed)(2)

CKSEL0

Select Clock source

0 (programmed)(2)

ATmega644PA Datasheet(PDF) 298 Page - ATMEL Corporation

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