Driving OLED with 28X2?

[cpedw]

I am hoping to use a 28X2 instead of the usual 18M2 to operate an OLED such as AXE133Y 16 by 2 but without the driver board. The objective is to incorporate the display driver into Kranenborg's frequency meter.
As a first step, I am trying to get a 28X2 to drive an OLED using a modified version of the standard AXE133 firmware. I have attached my modified firmware. I am using port C for the 8 bit parallel data with B.0 for ENABLE and A.4 for RS. These choices match unused parts of the Frequency Meter. It doesn't work. Instead of the Welcome Message:
Serial OLED 28X2
picaxe display
the display sometimes shows
==-MMMM-mmm}m] on the top line and blank bottom line on startup. Other times it stays blank.

I tried moving RS to A.0 and A.1 (A.4 is the programming serial out) but that didn't improve things at all.
The setup hs been breadboarded on an AXE091 dev board so there's a crystal in circuit; but setfreq should override that shouldn't it?
I would welcome suggestions for other changes to try. Or is there something about the 28X2 that means it can't drive an OLED?

Thanks,
Derek

 

[Technical]

Avoid A.4 if you can due to the clash with serial download pin. Also make sure you have used the correct (inner) left hand row of contacts on the AXE091 for the 28X2 legs 1-14 (particularly 11-14) - it's a common mistake to use the outer row 40X2 contacts by mistake.

 

[cpedw]

Avoid A.4 if you can due to the clash with serial download pin. Also make sure you have used the correct (inner) left hand row of contacts on the AXE091 for the 28X2 legs 1-14 (particularly 11-14) - it's a common mistake to use the outer row 40X2 contacts by mistake.

I was using the wrong contacts. Not the outermost row but the set intended for a 40 pin chip to plug into. Using the ones that you highlighted in red
has resolved my problem. It seems that usig A.4 is working OK. I just need to disconnect it from the OLED while programming.
Thanks.