AT90S8414
Preliminary
4-77
Table 23):
1. Power-up sequence:
Apply power between VCC and GND.
Set
R E S E T
pin to ’L’.
If a crystal is not connected across pins XTAL1 and XTAL2, apply a 1 MHz to 24 MHz clock to the XTAL1 pin and
wait for at least 10 milliseconds.
2. Enable serial programming by sending the Programming Enable serial instruction to pin MOSI/PB5. The frequency
of the shift clock supplied at pin SCK/PB7 needs to be less than the CPU clock at XTAL1 divided by 4.
3. The Program or EEPROM array is programmed one byte at a time by supplying the address and data together with
the appropriate Write instruction. The selected memory location is first automatically erased before new data is
written.
4. Any memory location can be verified by using the Read instruction which returns the content at the selected address
at serial output MISO/PB6.
polling is used to indicate the end of a write cycle, which typically takes less than 2.5 ms.
5. At the end of the programming session,
R E S E T
can be set high to commence normal operation.
6. Power-off sequence (if needed):
Set XTAL1 to ‘L’ (if a crystal is not used).
Set
R E S E T
to ‘H’
Turn VCC power off.
