Rainbow Electronics AT90LS4433 - Manual (Page 91)

91
AT90S/LS4433
1042G–AVR–09/02
Programming the Fuse Bits The algorithm for programming the Fuse bits is as follows (refer to “Programming the
Flash” for details on command and data loading):
A: Load Command “0100 0000”.
B: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
Bit 5 = SPIEN Fuse bit
Bit 4 = BODLEVEL Fuse bit
Bit 3 = BODEN Fuse bit
Bit 2 = CKSEL2 Fuse bit
Bit 1 = CKSEL1 Fuse bit
Bit 0 = CKSEL0 Fuse bit
Bits 7 - 6 = “1”. These bits are reserved and should be left unprogrammed (“1”).
1. Give WR a t
WLWH_PFB
wide negative pulse to execute the programming, t
WLWH_PFB
is found in Table 33. Programming the Fuse bits does not generate any activity
on the RDY/BSY pin.
Programming the Lock Bits The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” for details on command and data loading):
A: Load Command “0010 0000”.
B: Load Data Low Byte. Bit n = “0” programs the Lock bit.
Bit 2 = Lock bit 2
Bit 1 = Lock bit 1
Bits 7 - 3, 0 = “1”. These bits are reserved and should be left unprogrammed (“1”).
C: 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” for details on command loading):
A: Load Command “0000 0100”.
1. Set OE to “0”, and BS to “0”. The status of the Fuse bits can now be read at
DATA (“0” means programmed).
Bit 5 = SPIEN Fuse bit
Bit 4 = BODLEVEL Fuse bit
Bit 3 = BODEN Fuse bit
Bit 2 = CKSEL2 Fuse bit
Bit 1 = CKSEL1 Fuse bit
Bit 0 = CKSEL0 Fuse bit
2. Set BS to “1”. The status of the Lock bits can now be read at DATA (“0” means
programmed).
Bit 2 = Lock Bit 2
Bit 1= Lock Bit 1
3. Set OE to “1”.