Datasheet

ATmega48/88/168 Automotive [DATASHEET]
7530K–AVR–07/14
252
25.7.9 Programming the Fuse High Bits
The algorithm for programming the use high bits is as follows (refer to Section 25.7.4 “Programming the Flash” on page 248
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.
25.7.10 Programming the Extended Fuse Bits
The algorithm for programming the extended fuse bits is as follows (refer to
Section 25.7.4 “Programming the Flash” on page 248 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 bit.
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 25-5. Programming the FUSES Waveforms
25.7.11 Programming the Lock Bits
The algorithm for programming the lock bits is as follows (refer to Section 25.7.4 “Programming the Flash” on page 248 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 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.
0x40
AC
DATA
XA1
XA0
BS1
BS2
XTAL1
WR
PAGEL
RDY/BSY
OE
RESET +12V
0x40 0x40 DATA
A
DATA XX
C
Write Fuse Low byte Write Fuse High byte Write Extended Fuse byte
XXDATA
A
XX
C