Rainbow Electronics AT90C8534 - Manual (Page 43)

AT90C8534
43
Programming the EEPROM
The programming algorithm for the EEPROM data memory is as follows (refer to “Programming the Flash” for details on
command, address and data loading):
1. A: Load Command “0001 0001”.
2. B: Load Address High Byte ($00 - $01).
3. C: Load Address Low Byte ($00 - $FF).
4. D: Load Data Low Byte ($00 - $FF).
5. E: Write Data Low Byte.
Reading the EEPROM
The algorithm for reading the EEPROM memory is as follows (refer to “Programming the Flash” for details on command
and address loading):
1. A: Load Command “0000 0011”.
2. B: Load Address High Byte ($00 - $01).
3. C: Load Address Low Byte ($00 - $FF).
4. Set OE to “0”, and BS to “0”. The EEPROM data byte can now be read at DATA.
5. Set OE to “1”.
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):
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
Bits 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 Lock Bits
The algorithm for reading the Lock bits is as follows (refer to “Programming the Flash” for details on command loading):
1. A: Load Command “0000 0100”.
2. Set OE to “0”, and BS to “1”. The status of the Lock bits can now be read at DATA.
Bit 7: Lock Bit1 (“0” means programmed)
Bit 6: Lock Bit2 (“0” means programmed)
3. Set OE to “1”.
Observe that BS must be set to “1”.
Reading the Signature Bytes
The algorithm for reading the signature bytes is as follows (refer to “Programming the Flash” 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”.