Specifications

84
AT90S8515
0841G–09/01
Bit 5 = SPIEN Fuse bit
Bit 0 = FSTRT Fuse bit
Bit 7-6, 4-1 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3. Give WR a t
WLWH_PFB
-wide negative pulse to execute the programming,
t
WLWH_PFB
is found in Table 30. 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” on page 81 for details on command and data loading):
1. A: Load Command “0010 0000”.
2. D: Load Data Low Byte. Bit n = “0” programs the Lock bit.
Bit 2 = Lock Bit2
Bit 1 = Lock Bit1
Bit 7 - 3, 0 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3. E: 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” on page 81 for details on Command loading):
1. A: Load Command “0000 0100”.
2. Set OE
to “0”, and BS to “1”. The status of the Fuse and Lock bits can now be
read at DATA (“0” means programmed).
Bit 7 = Lock Bit1
Bit 6 = Lock Bit2
Bit 5 = SPIEN Fuse bit
Bit 0 = FSTRT Fuse bit
3. Set OE
to “1”.
Observe that BS needs to be set to “1”.
Reading the Signature Bytes The algorithm for reading the signature bytes is as follows (refer to “Programming the
Flash” on page 81 for details on command and address loading):
1. A: Load Command “0000 1000”.
2. C: Load Address Low Byte ($00 - $02).
Set OE
to “0”, and BS to “0”. The selected signature byte can now be read at DATA.
3. Set OE to “1”.