
199
8008H–AVR–04/11
ATtiny48/88
Figure 21-5. Programming the FUSES Waveforms
21.2.11
Programming the Lock Bits
194 for details on command and data loading):
A: Load command “0010 0000”
C: Load data low byte. Bit n = “0” programs the Lock bit. If LB1 and LB2 have been
programmed, it is not possible to program the Lock Bits by any External Programming mode
Give WR a negative pulse and wait for RDY/BSY to go high
Lock bits can only be cleared by executing Chip Erase.
21.2.12
Reading Fuse and Lock Bits
194 for details on command loading):
A: Load command “0000 0100”
Set OE to “0”, BS2 to “0” and BS1 to “0”. Low fuse bits can now be read at DATA (“0” means
programmed)
Set OE to “0”, BS2 to “1” and BS1 to “1”. High fuse bits can now be read at DATA (“0” means
programmed)
Set OE to “0”, BS2 to “1”, and BS1 to “0”. Extended fuse bits can now be read at DATA (“0”
means programmed)
Set OE to “0”, BS2 to “0” and BS1 to “1”. Lock bits can now be read at DATA (“0” means
programmed)
Set OE to “1”
Fuse and lock bit mapping is illustrated in
Figure 21-6, below.
RDY/BSY
WR
OE
RESET +12V
PAGEL
0x40
DATA
XX
XA1
XA0
BS1
CLKI
AC
0x40
DATA
XX
AC
Write Fuse Low byte
Write Fuse high byte
0x40
DATA
XX
AC
Write Extended Fuse byte
BS2