Datasheet

Figure 32-4. Programming the FUSES Waveforms
RDY/BSY
WR
OE
RESET +12V
PAGEL
0x40
DATA
DATA
XX
XA1
XA0
BS1
XTAL1
A C
0x40 DATA XX
A C
Write Fuse Low byte Write Fuse high byte
0x40 DATA XX
A C
Write Extended Fuse byte
BS2
32.8.11 Programming the Lock Bits
The algorithm for programming the Lock bits is as follows (refer to 32.8.4 Programming the Flash for
details on command and data loading):
1. Step A: Load Command “0010 0000”.
2. Step C: Load Data Low Byte. Bit n = “0” programs the Lock bit. If LB mode 3 is programmed (LB1
and LB2 is programmed), it is not possible to program the Boot Lock bits by any External
Programming mode.
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.
32.8.12 Reading the Fuse and Lock Bits
The algorithm for reading the Fuse and Lock bits is as follows (refer to 32.8.4 Programming the Flash for
details on Command loading):
1. Step 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”.
ATmega48PA/88PA/168PA
Memory Programming (MEMPROG)
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40002011A-page 377