Joseph Smith wrote:
Ok, I have finished the "The Circuit Explained" section. I need some feedback, bueller?
A series of 1K ohms resistors 250mW (1/4W) on data lines D0 - D6 convert the signals from 5V to 3.3v needed by the flash chip.
This sentence and design is not so good. A resistor can not be used to safely lower voltage. The ST buffer has absolute max DC Input VCC+0.5, which is clearly exceeded by your circuit when that resistor is the only thing between the parallell port and the buffer. The flash chips are likely to have even stricter ratings.
I would revisit this. At the very least use two resistors as a voltage divider, but it will probably mean that you can not program the LPC/FWH signals as quickly as with better level shifting. Ideally use a fast buffer with 5V-tolerant input and 3V output, but diodes work too. Just make sure they have the right voltage drop.
//Peter