ATmega32HVB datasheet(210/273 Pages) ATMEL

210 / 273 page

210

8042A–AVR–07/09

ATmega16HVB/32HVB

30.2.2

Low Byte

Notes:

1. The Watchdog is enabled/disabling by writing to the Watchdog Timer Control and Status Reg-

ister (WDTCSR). But as a fail-safe, the WDTON fuse can be used to force the Watchdog to run

in System Reset mode.

2. The SUTx fuse bits are used to configure the startup time from sleep or reset. By default the

longest startup time is selected.

3. The default OSCSEL1:0 setting should not be changed. OSCSEL1:0="00" is reserved for test

purpose. Other values are reserved for future use.

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.

30.2.3

Latching of Fuses

The fuse values are latched when the device enters programming mode and changes of the

fuse values will have no effect until the part leaves Programming mode. This does not apply to

the EESAVE Fuse which will take effect once it is programmed. The fuses are also latched on

Power-up in Normal mode.

30.3

Signature Bytes

All Atmel microcontrollers have a three-byte signature code which identifies the device. This

code can be read in both Programming mode, also when the device is locked. The three bytes

reside in a separate address space. The signature bytes of ATmega16HVB/32HVB is given in

Table 30-5.

Table 30-4.

Fuse Low Byte

Bit No

Fuse Low Byte

Description

Default Value

WDTON

Watchdog Timer always on

1 (unprogrammed)(1)

EESAVE

EEPROM memory is preserved

through the Chip Erase

1 (unprogrammed, EEPROM

not preserved)

SPIEN

Enable Serial Programmable Data

Downloading

0 (programmed, SPI

programming enabled)

SUT2

Select start-up time

1 (unprogrammed)(2)

SUT1

Select start-up time

1 (unprogrammed)(2)

SUT0

Select start-up time

1 (unprogrammed)(2)

OSCSEL1

Oscillator Select

1(unprogrammed)(3)

OSCSEL0

Oscillator Select

0(programmed)(3)

Table 30-5.

Device ID

Part

Signature Bytes Address

0x000

0x001

0x002

ATmega16HVB

0x1E

0x94

0x0D

ATmega32HVB

0x1E

0x95

0x10

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