ST7066U 20x4 LCD problems(Solved)

[augustinetez]

Confirmed by metering - the pins are changing state.

 

[Dan Soze]

Ok, then perhaps you have another issue in your hardware.

 

[augustinetez]

Dan, whether you know it or not, you are a marvel.

The mystery of why the 16x2 works and the 20x4 didn't is solved and it is/was a hardware issue.

And the problem was - the encoder's common pin is taken to gnd via the wiring harness for the 16x2 LCD, when it's unplugged to attach the 20x4 - no gnd connection for the encoder common pin

 

[augustinetez]

And your code works. now that I have corrected that anomaly - thankyou.

 

[Dan Soze]

Congratulation, you are a genius!

 

[augustinetez]

Just goes to prove there is no such thing as a stupid question.

If you hadn't asked it, I would be sitting here looking up the number for Ghostbusters about now

Thankyou for everybody's help through this thread, hopefully I will get the chance to repay it somewhere.

 

[Dan Soze]

You shared a photo of your setup here's one of mine: