Hi,
I am searching for an LCD that is HD44780 compatible, min. 4x20 in size and that runs on 3.3V.
Suggestions are most welcome.
Thanks, Hans.
Most character LCD's use the HD44780 controller or understand the commands. Its best to go to your local supplier and see what they got, because there are many different manufacturers who may or may not supply to your area.
As for 3.3V are you wanting this because you are running 3.3V logic , why not look at a level translator to interface to 5V TTL.
Thank you Zageek,
Specifics is what I need, purchasing area is least important.
Which LCD('s) including controller would you suggest?
Same for the level translator.
Thanks, Hans.
Most character LCD's that use the HD44780 or equivalent controller work only in the 4.5~5.0V range. Although the specifications for the HD44780 states that the IC can run as low as 2.7V, it is the output of the HD44780 IC to the LCD panel that becomes the problem. This is where low or no contrast becomes an issue at 3.3V.
The other issue is most data sheets show timing for 5V, so if you use 3.3V the timing will be slowed down, but there is very limited information of the actual timing specs.
If you could use a standard 20x4 LCD at 5V, you will find more displays and support as well. But if you are limited to 3.3V supply and logic, you may need to do as zageek recommends.
I've adopted 3.3V as my standard and agree that there is not as much choice regarding LCD displays as there is with 5V models.
For my 4x20 displays I use the New Haven Display NHD-0420DZ-FL-YBW-3V3 transflective unit. Its dynamic characteristics are well documented in the user manual. Delay times are a function of controller oscillator frequency which is 270 KHz for 5V and 3V3 displays, therefore the same. The contrast ratio is 6 for both the 5V and 3V3 units.
I have found them to be rugged and reliable and very readable in direct sunlight which is important to me. As they are transflective their LED backlight provides equal readability in the dark.
You can check their website for other 3V3 displays.
EmilyJane,
hm, very interesting LCD you're suggesting and using, thank you.
What about ARDUINO compatible code for the controller SPLC780D that LCD is using?
Is it really compatible with a HD44780 controller?
I am intending to use an LCD on the Seeeduino v2.12 that must be running on 3.3V as there is another device (MAX3421E) that requires the operating voltage to be 3.3V.
The reason I am looking for an LCD with a HD44780 compatible controller is that there is plenty of working code around. But as 'hd44780helper' pointed out, that IC wants 5V and not 3.3V.
snahL,
Based on the command set in the spec, it looks the same as those for the HD44780 LCD. So, the HD44780 stuff should work on the New Haven LCD also.
hd44780helper,
well, that's good news, thanks.
I think that I'll try the New Haven Display NHD-0420DZ-FL-YBW-3V3 and post back.
While I hesitate to use the term 100% about anything, the SPLC780D is totally compatible with the HD44780. I use the Arduio LiquidCrystal library to drive it in 4-bit mode.
It's possible that hd44780helper is thinking of an older part. Since sometime late in the last century 
the Hitachi HD44780 could more properly be described as "5 volt tolerant" as it is designed to run at about a 3V nominal input. The same is true of the SPLC780D.
I wish you good luck with your project.