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ATMEGA8U2_14 Datasheet, PDF (257/310 Pages) ATMEL Corporation – 125 Powerful Instructions – Most Single Clock Cycle Execution | |||
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ATmega8U2/16U2/32U2
25.7.9
Programming the Fuse High Bits
The algorithm for programming the Fuse High bits is as follows (refer to âProgramming the
Flashâ on page 253 for details on Command and Data loading):
1. A: Load Command â0100 0000â.
2. C: Load Data Low Byte. Bit n = â0â programs and bit n = â1â erases the Fuse bit.
3. Set BS2, BS1 to â01â. This selects high data byte.
4. Give WR a negative pulse and wait for RDY/BSY to go high.
5. Set BS2, BS1 to â00â. 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 âProgramming the
Flashâ on page 253 for details on Command and Data loading):
1. 1. A: Load Command â0100 0000â.
2. 2. C: Load Data Low Byte. Bit n = â0â programs and bit n = â1â erases the Fuse bit.
3. 3. Set BS2, BS1 to â10â. This selects extended data byte.
4. 4. Give WR a negative pulse and wait for RDY/BSY to go high.
5. 5. Set BS2, BS1 to â00â. This selects low data byte.
Figure 25-5. Programming the FUSES Waveforms
Write Fuse Low byte
Write Fuse high byte
DATA
A
C
0x40
DATA
XX
A
C
0x40
DATA
XX
XA1
XA0
BS1
BS2
XTAL1
WR
RDY/BSY
RESET +12V
OE
PAGEL
Write Extended Fuse byte
A
C
0x40
DATA
XX
25.7.11
Programming the Lock Bits
The algorithm for programming the Lock bits is as follows (refer to âProgramming the Flashâ on
page 253 for details on Command and Data loading):
1. A: Load Command â0010 0000â.
2. C: Load Data Low Byte. Bit n = â0â 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.
7799DâAVRâ11/10
257
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