Using a 40*4 LCD display with 2 enable lines

Hi all, I have a 40*4 LCD display. I use the LiquidCristal library but it doesn't work ok. I checked the datasheet and it shows that you have to use 2 Enable lines E1 and E2. E1 for top 2 rows, E2 for lower 2 rows. although the library tells you that you can use 4 row displays it doesn't support the 2 enable lines?? I tried tying 2 lines together but that doesn't work. Also setting E2 on the display separately just before writing to rows 3 and 4 doesn't work. does someone has experience in this and knows how to solve this?

thanks, Rene

You can use two instances of the standard library, one associated with each enable line, but I’m pretty sure that the HD44780 library, which is available via the Arduino library manager, can handle the device almost transparently.

Don

floresta: You can use two instances of the standard library, one associated with each enable line, but I'm pretty sure that the HD44780 library, which is available via the Arduino library manager, can handle the device almost transparently.

Don

Unfortunately there is no support for the dual enable displays in the hd44780 library. And while I have considered it, I haven't added the ability to treat multiple displays like a single larger display.

I can't remember where I've seen it but I have seen a LiquidCrystal compatible library out there that does support these types of displays.

--- bill

Ok, here is the one I remember: https://www.pjrc.com/teensy/td_libs_LiquidCrystal.html

I haven't done any testing with it so I don't know how well it works.

--- bill

The library at the link in #3 is derived from LiquidCrystal440, written about 10 years ago by John Raines, which was designed for the earlier (pre 1.0) versions of the Arduino IDE.

LiquidCrystal440 was revised a year or so later for Arduino 1.0 and renamed LiquidCrystal1.0. You can get both of these libraries here.

I don't know if either has been updated as the IDE has evolved beyond 1.0.

Don