BIPOLAR PROM PROGRAMMER


Another one in the arena !

This one is based on the Atmega to repeat easily programming a PROM.

It reads the source from a master PROM
It writes what is memory to a virgin PROM

Values can be modified on the fly if needed. That is similar to
the 'manual' programmers found everywhere.

A default PROM file is used when 'Read' is pressed and nothing is in the socket.
The goal of this project was programming a dozen of PROMS, so it makes sense for me
to have that default loaded.

TODO: use the internal eeprom of the mega to store/retrieve PROM files. 
TODO: use the serial port to send files (remember entering 32 values is not really
time consumming, so this is luxury.

I'm using KiCad 5. It works for me until I upgrade my old laptop. Don't send request
about version.


The code is occupying 85% of the AtMega88. What is code consumming is
the human interface ! Moving to atMega328 is possible.
TODO: remove DigitalRead DigitalWrite functions (code consumming I think)

version 1.0 of the pcb was really botched to work. Version v1.1 fixed all that
but I made a mistake with the G6K relay footprint. In this repository, this is
fixed.
But I still have 4 usable PCB from JLCPCB. Pin 1 and 8 of each relay need to be
swapped. It can be done by soldering the relay on the other side. I choose to
put them on the correct side and inserted insulation on the two pins then solder
correctly.

Another thing is the ZIF socket. AliExpress 3M Textool is shit reproduction.
I ordered Aries reproduction, much better but pin space is 'wide'. But they
can be used. They can also be opened (a good hammer and strong pin) to 
reinsert each contact to get the narrow version.

HOW TO used

Insert the PROM to copy in the 'Read' socket, press 'R' button

The CRC32 is displayed until another key is pressed.
If all zero is read, then the default PROM file is used. 
This is signaled by a double beep.

Use + / - to display each address and content.
Press V to edit a value (with + / -). Display starts
blinking.
Press V again to accept the updated value.

When everything is OK, insert a virgin PROM and press 'W'
Program will fuse bit 0 on each 32 position, then bit 1
then ... This limits the relays actuating.

Read of the 'Write' socket is done for comparison. When
green LED lits, it is a success.
If not, retry. Only failed bits will be refused.

The serial port reports outputs what the programmer is doing.
Is is not required to have a terminal nut it helps.


I had in mind some flexibility for the current programming 
(the pulse). I did not explore possibilities of burning
other brand.
I have tested the programmer with

N82S23AN (K8608) from Signetics.


I have 4 spare PCB to sell (instead of asking 5 new ones to JLPCB).
I'm not doing that for the money of course but avoid filling my bin.


About the PCB
I wanted sockets and button covered properly in a box. This why
all 'big' components are on the other side.