ATMEGA64L-8MI View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

ATMEGA64L-8MI

8-bit AVR® Microcontroller with 64K Bytes In-System Programmable Flash

Atmel Corporation 

ATmega64(L)

Programming the Lock Bits

Reading the Fuse and Lock

Bits

Figure 142. Programming the FUSES Waveforms

Write Fuse Low byte

Write Fuse high byte

DATA

A

C

0x40

DATA

XX

A

C

0x40

DATA

XX

XA1

XA0

BS1

BS2

XTAL1

WR

RDY/BSY

RESET +12V

OE

PAGEL

Write Extended Fuse byte

A

C

0x40

DATA

XX

The algorithm for programming the Lock bits is as follows (refer to “Programming the

Flash” on page 298 for details on Command and Data loading):

1. A: Load Command “0010 0000”.

2. C: Load Data Low Byte. Bit n = “0” programs the Lock bit.

3. Give WR a negative pulse and wait for RDY/BSY to go high.

The Lock bits can only be cleared by executing Chip Erase.

The algorithm for reading the Fuse and Lock bits is as follows (refer to “Programming

the Flash” on page 298 for details on Command loading):

1. A: Load Command “0000 0100”.

2. Set OE to “0”, BS2 to “0” and BS1 to “0”. The status of the Fuse Low bits can

now be read at DATA (“0” means programmed).

3. Set OE to “0”, BS2 to “1” and BS1 to “1”. The status of the Fuse High bits can

now be read at DATA (“0” means programmed).

4. Set OE to “0”, BS2 to “1” and BS1 to “0”. The status of the Extended Fuse bits

can now be read at DATA (“0” means programmed).

5. Set OE to “0”, BS2 to “0” and BS1 to “1”. The status of the Lock bits can now be

read at DATA (“0” means programmed).

6. Set OE to “1”.

2490G–AVR–03/04

303

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