Pro mini 3.3v + enc28j60 3.3v + lcd 5v

Other Hardware Displays
1

Ok got a voltage problem, pro min and wireless module at 3.3v but lcd at 5v. However looking at the lcd datasheet it says the voltage is ok for the display and logic at 2 to 5.5v. http://www.hobbytronics.co.uk/datasheets/HD44780.pdf should it be ok?

Thanks

2

That's the link to the datasheet for the generic LCD controller, not for the display itself so we really can't tell. Does your display actually use an Hitachi controller?

Don

3

Thanks for the reply and good question!

on the Hobbytronics site it states "Standard Hitachi HD44780 compatable interface for easy connection to microcontrollers" then lists the HD44780 datasheet... mmmm

thanks again

4

They are "compatible" with the registers and commands.
The cheap 16x2 lcd displays need 5V to operate. In my circuit it is the first thing to stop working with lower voltage.
I don't know about the logic signals. They could be recognized at 3.3V, but the display itself needs 5V.

5

I have a regulated 5v supply and think the digital data lines should work at 3.3v. Can i supply the LCD with the regged 5v direct? e.g it won't feed through to the 3.3v Arduino board?

thanks

6

If you use the pins as inputs it won't.
So tie the R/W pin to ground.
Without use of th R/W pin, the software should use software delays, but that is what the CrystalLibrary is doing if the R/W pin is not defined.