at90pwm81-16se ATMEL Corporation, at90pwm81-16se Datasheet - Page 260

• Manufacturer Part Number: at90pwm81-16se
• Description: 8-bit Avr Microcontroller With 8k Bytes In- System Programmable Flash
• Manufacturer: ATMEL Corporation

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22.7.12
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AT90PWM81
Programming the Lock Bits
Reading the Fuse and Lock Bits
Reading the Signature Bytes
The algorithm for programming the Lock bits is as follows (refer to
for details on Command and Data loading):
The Lock bits can only be cleared by executing Chip Erase.
The algorithm for reading the Fuse and Lock bits is as follows (refer to
256
Figure 22-6.
The algorithm for reading the Signature bytes is as follows (refer to
for details on Command and Address loading):
1.
2.
3.
1.
2.
3.
4.
5.
6.
1.
2.
3.
4.
for details on Command loading):
A: Load Command “0010 0000”.
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 Pro-
gramming mode.
Give WR a negative pulse and wait for RDY/BSY to go high.
A: Load Command “0000 0100”.
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).
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).
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).
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).
Set OE to “1”.
A: Load Command “0000 1000”.
B: Load Address Low Byte (0x00 - 0x02).
Set OE to “0”, and BS1 to “0”. The selected Signature byte can now be read at DATA.
Set OE to “1”.
Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read
Fuse Low Byte
Extended Fuse Byte
Fuse High Byte
Lock Bits
BS2
BS2
0
1
0
1
BS1
“Programming the Flash” on page 256
“Programming the Flash” on page 256
“Programming the Flash” on page
0
1
DATA
7734M–AVR–03/10