ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 303

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Programming the Lock Bits
Reading the Fuse and Lock
Bits
2490G–AVR–03/04
Figure 142. Programming the FUSES Waveforms
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
3. Set OE to “0”, BS2 to “1” and BS1 to “1”. The status of the Fuse High bits can
4. Set OE to “0”, BS2 to “1” and BS1 to “0”. The status of the Extended Fuse bits
5. Set OE to “0”, BS2 to “0” and BS1 to “1”. The status of the Lock bits can now be
6. Set OE to “1”.
RESET +12V
RDY/BSY
now be read at DATA (“0” means programmed).
now be read at DATA (“0” means programmed).
can now be read at DATA (“0” means programmed).
read at DATA (“0” means programmed).
PAGEL
XTAL1
DATA
BS2
XA1
XA0
BS1
WR
OE
0x40
A
DATA
C
Write Fuse Low byte
XX
0x40
A
DATA
C
Write Fuse high byte
XX
ATmega64(L)
0x40
A
DATA
C
Write Extended Fuse byte
XX
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