m27c322 with home made flashcat xport 2 adapter help

[wes44]

just a quick question to anyone in the know before I try and diagnose the issue myself.

I built a 42pin dip adapter as per the schematics here

https://www.embeddedcomputers.net/products/ParallelAdapters/SCM_DIP42.png

The schematics appear to show that the 16mb / 32mbit switch is wired to change

Pin 32 <VPP / A20>
Pin 13 <OE / VPP>

I built this and verified it is wired correctly but it doesn't seem to work right.. if I put the switch into 16mbit mode it will detect the 322 eprom and then i can switch it to 32mb to program it else it will not program (lack of VPP)..

If I leave it in 32mbit mode then the chip isn't detected at all.

starting the chip off in the 16mbit mode then swapping to 32mbit I can program the whole 32mbit correctly and verify it.

Is this how the stock adapter works too or is the schematic incorrect / i'm doing something different.

Thanks in advance if anyone knows.

 

[Pantheon]

This is because the schematic is out of date. You need a load switch on the VPP pin that is controlled from the CLE pin on XPORT.

 

[wes44]

Hey, thank you for the quick reply! I understand.. that is pretty much how I was going to implement my temporary fix.

I'll be ordering one from the website the next time I order some tsop adapters but for now it is working!

Thanks again