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High-voltage Serial
Programming Algorithm
1004D–09/01
To program and verify the AT90S/LS2323 and AT90S/LS234 in the high-voltage Serial
Programming mode, the following sequence is recommended (see instruction formats in
Table 16):
1. Power-up sequence: Apply 4.5 - 5.5V between V
PB0 to "0" and wait at least 100 ns. Then, if the RCEN Fuse is not programmed,
toggle XTAL1/PB3 at least four times with minimum 100 ns pulse width. Set PB3
to "0". Wait at least 100 ns. Or, if the RCEN Fuse is programmed, set PB3 to "0".
Wait for least 4 µs. In both cases, apply 12V to RESET and wait at least 100 ns
before changing PB0. Wait 8 µs before giving any instructions.
2. The Flash array is programmed one byte at a time by supplying first the address,
then the low and high data bytes. The write instruction is self-timed; wait until the
PB2 (RDY/BSY) pin goes high.
3. The EEPROM array is programmed one byte at a time by supplying first the
address, then the data byte. The write instruction is self-timed; wait until the PB2
(RDY/BSY) pin goes high.
4. Any memory location can be verified by using the Read instruction, which returns
the contents at the selected address at serial output PB2.
5. Power-off sequence:Set PB3 to "0".
Set RESET to "0".
Turn V
power off.
CC
When writing or reading serial data to the device, data is clocked on the rising edge of
the serial clock. See Figure 33, Figure 34 and Table 17 for details.
Figure 33. High-voltage Serial Programming Waveforms
SERIAL DATA INPUT
PB0
SERIAL INSTR. INPUT
PB1
SERIAL DATA OUTPUT
PB2
SERIAL CLOCK INPUT
XTAL1/PB3
AT90S/LS2323/2343
MSB
MSB
MSB
0
1
2
3
4
5
and GND. Set RESET and
CC
LSB
LSB
LSB
6
7
8
9
10
39
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