Rainbow Electronics ATtiny28L - Manual (Page 48)

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ATtiny28L/V
1062E–10/01
1. Set BS to “1”. This selects high data.
2. Give WR a negative pulse. This starts programming of the data byte. RDY/BSY
goes low.
3. Wait until RDY/BSY goes high to program the next byte.
(See Figure 38 for signal waveforms.)
The loaded command and address are retained in the device during programming. For
efficient programming, the following should be considered:
• The command needs to be loaded only once when writing or reading multiple
memory locations.
• Address high byte only needs to be loaded before programming a new 256-word
page in the Flash.
• Skip writing the data value $FF, that is, the contents of the entire Flash after a Chip
Erase.
These considerations also apply to Flash and signature bytes reading.
Reading the Flash The algorithm for reading the Flash memory is as follows (refer to “Programming the
Flash” for details on command and address loading):
A: Load Command “0000 0010”.
B: Load Address High Byte ($00 - $03).
C: Load Address Low Byte ($00 - $FF).
1. Set OE to “0”, and BS to “0”. The Flash word low byte can now be read at DATA.
2. Set BS to “1”. The Flash word high byte can now be read from DATA.
3. Set OE to “1”.
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”.
D: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
Bit 4 = INTCAP Fuse
Bit 3 = CKSEL3 Fuse
Bit 2 = CKSEL2 Fuse
Bit 1 = CKSEL1 Fuse
Bit 0 = CKSEL0 Fuse
Bits 7 - 5 = “1”. These bits are reserved and should be left unprogrammed (“1”).
E: Write Data Low Byte.
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”.
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”).
E: Write Data Low Byte.
The Lock bits can only be cleared by executing Chip Erase.