ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 266

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Programming the Fuse Low
Bits
Programming the Fuse High
Bits
Programming the Extended
Fuse Bits
Programming the Lock Bits
266
ATmega325/3250/645/6450
The algorithm for programming the Fuse Low bits is as follows (refer to “Programming
the Flash” on page 262 for details on Command and Data loading):
1. A: Load Command “0100 0000”.
2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
3. Give WR a negative pulse and wait for RDY/BSY to go high.
The algorithm for programming the Fuse High bits is as follows (refer to “Programming
the Flash” on page 262 for details on Command and Data loading):
1. A: Load Command “0100 0000”.
2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
3. Set BS1 to “1” and BS2 to “0”. This selects high data byte.
4. Give WR a negative pulse and wait for RDY/BSY to go high.
5. Set BS1 to “0”. This selects low data byte.
The algorithm for programming the Extended Fuse bits is as follows (refer to “Program-
ming the Flash” on page 262 for details on Command and Data loading):
1. 1. A: Load Command “0100 0000”.
2. 2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse
3. 3. Set BS1 to “0” and BS2 to “1”. This selects extended data byte.
4. 4. Give WR a negative pulse and wait for RDY/BSY to go high.
5. 5. Set BS2 to “0”. This selects low data byte.
Figure 115. Programming the FUSES Waveforms
The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” on page 262 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. If LB mode 3 is pro-
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.
RESET +12V
RDY/BSY
bit.
grammed (LB1 and LB2 is programmed), it is not possible to program the Boot
Lock bits by any External Programming mode.
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
0x40
A
DATA
C
Write Extended Fuse byte
XX
2570A–AVR–09/04