About 3 weeks , due to HK Post's system .
But adafruit's LCD is much cheaper anyway ...
Thank you guys I think I'll get the 4x20 LCD but I just want to make sure of some stuff.
I still only need 6 I/O on the arduino.
and it said that the whole screen is 2x7cm that's means that the digits are 5mm is that right or did I read it wrong.
I have a solution to our LCD problems :
http://www.dealextreme.com/p/16-x-2-character-lcd-display-module-with-blue-backlight-121356
It's a HD44780-driven display
That is the way I read it and WAY too small for a power supply display, in my opinion.
Just think of it the same way you would having two 595s connected. The HD44780 only supports 2*20 max, so to get 4*20 there are two of them tied together.
"The lines on the screen can be a little misleading; both lines 1 and 3, and both lines 2 and 4 are treated as though they are one line each and that the display were really 2 lines of 40 characters each. As a result, after 20 characters have been written on each line the display wraps unexpectedly. The first character after line 1 will end up on line 3 instead of line 2, and the first character after line 2 will end up on line 4 instead of line 3. If a character is written after the end of line 3 it will end up at the beginning of line 2. The next write after line 4, though, writes to line 1 as anticipated. Luckily, this is accounted for in software as the microcontroller keeps track of the current position of the cursor."
A 4x20 character display is logically arranged as two lines, although physically it appears as four lines. The mapping is like this
Physical line 1: logical line 1, part 1
Physical line 2: logical line 2, part 1
Physical line 3: logical line 1, part 2
Physical line 4: logical line 2, part 2