121
ATmega161(L)
1228B–09/01
Programming the Fuse Bits
The algorithm for programming the Fuse bits is as follows (refer to “Programming the
Flash” on page 117 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.
Bit 6 = BOOTRST Fuse bit
Bit 5 = SPIEN Fuse bit
Bit 4 = BODLEVEL Fuse bit
Bit 3 = BODEN Fuse bit
Bits 2 - 0 = CKSEL2..0 Fuse bits
Bit 7 = “1”. This bit is reserved and should be left unprogrammed (“1”).
3.
Give WR a negative pulse and wait for RDY/BSY to go high.
Programming the Lock Bits
The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” on page 117 for details on command and data loading):
1.
A: Load Command “0010 0000”.
2.
D: Load Data Low Byte. Bit n = “0” programs the Lock bit.
Bit 5 = Boot Lock Bit12
Bit 4 = Boot Lock Bit11
Bit 3 = Boot Lock Bit02
Bit 2 = Boot Lock Bit01
Bit 1 = Lock Bit2
Bit 0 = Lock Bit1
Bits 7 - 6 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3.
L: Write Data Low Byte.
The Lock bits can only be cleared by executing Chip Erase.
Reading the Fuse and Lock
Bits
The algorithm for reading the Fuse and Lock bits is as follows (refer to “Programming
the Flash” on page 117 for details on command loading):
1.
A: Load Command “0000 0100”.
2.
Set OE to “0”, and BS to “0”. The status of the Fuse bits can now be read at
DATA (“0” means programmed).
Bit 6 = BOOTRST Fuse bit
Bit 5 = SPIEN Fuse bit
Bit 4 = BODLEVEL Fuse bit
Bit 3 = BODEN Fuse bit
Bits 2 - 0 = CKSEL2..0 Fuse bits
3.
Set OE to “0”, and BS to “1”. The status of the Lock bits can now be read at
DATA (“0” means programmed).
Bit 5 = Boot Lock Bit12
Bit 4 = Boot Lock Bit11
Bit 3 = Boot Lock Bit02
Bit 2 = Boot Lock Bit01
Bit 1 = Lock Bit2
Bit 0 = Lock Bit1
4.
Set OE to “1”.
Reading the Signature Bytes
The algorithm for reading the Signature bytes is as follows (refer to “Programming the
Flash” on page 117 for details on command and address loading):
1.
A: Load Command “0000 1000”.
2.
C: Load Address Low Byte ($00 - $02).