View source for Prototype RS232 AVR parallel flash programmer

== AVR to Flash interface pinout ==

The interface on the AVR side consists of
* 8-bit direct databus
* 3-bit control bus (CE/OE/WE)
* 4 line address bus - expands upto 24-bit

=== Data bus ===
* data bits 7..2 = PD7 - PD2
* data bits 1..0 = PB1 - PB0

=== Control bus ===
* !CE = PC3
* !OE = PC4
* !WE = PC5

=== Address bus ===
The address bus consists of 3 shift registers (74HC164N) with common clock signal and outputs arranged so
that with 1 clock pulse one can set A2..A0 - so with 6 pulses (12 toggles) one can set A17..A0,
8 pulses (maximum) would give A23..A0.

 The shift register that outputs
 A0,3,6,9,12,15...	A1,4,7,10,13,16...	A2,5,8,11,14,17
 is at				
 PC1			PC0			PB4

The clock line is PB2 - usage is that you set the bit values to "send",
then send a pulse (up+down transitions) on the clock line.