user639: Can the Arduino Mega2560 use the New Haven NHD-0420D3Z-NSW-BBW-V3 LCD panel by controlling it with the New LiquidCrystal library? What cable will you use to connect the LCD to Arduino, are there screw terminals on the LCD board to secure the connections? It seems like only 4 connections are needed, for GND, VCC, SDA, SCL.

user368: Unfortunately you cannot control that display using that library; the library expects to be connected to a HD44780-compatible driver but the display uses a fully custom control scheme. You may be able to adapt the library to the scheme, but I have not looked at that specifically.
I2C itself only requires 3 connections: SDA, serial data; SCL serial clock; GND, ground reference. Since the display is not powered separately it also requires power, in this case 5V. Since the display can only communicate at 100kHz you don't need to be too terribly concerned about cable quality; Cat3 or even telephone cable is acceptable as long as you don't exceed a few feet in length. Don't forget the external pullup resistors though, on SDA and SCL.

639: <p>Can the Arduino Mega2560 use the <a href="http://www.newhavendisplay.com/nhd0420d3znswbbwv3-p-5745.html" rel="nofollow">New Haven NHD-0420D3Z-NSW-BBW-V3</a> LCD panel by controlling it with the <a href="https://bitbucket.org/fmalpartida/new-liquidcrystal" rel="nofollow">New LiquidCrystal library</a>? What cable will you use to connect the LCD to Arduino, are there screw terminals on the LCD board to secure the connections? It seems like only 4 connections are needed, for <code>GND</code>, <code>VCC</code>, <code>SDA</code>, <code>SCL</code>.</p>
 368: <p>Unfortunately you cannot control that display using that library; the library expects to be connected to a HD44780-compatible driver but the display uses a fully custom control scheme. You may be able to adapt the library to the scheme, but I have not looked at that specifically.</p>

<p>I<sup>2</sup>C itself only requires 3 connections: SDA, serial data; SCL serial clock; GND, ground reference. Since the display is not powered separately it also requires power, in this case 5V. Since the display can only communicate at 100kHz you don't need to be <em>too</em> terribly concerned about cable quality; Cat3 or even telephone cable is acceptable as long as you don't exceed a few feet in length. <a href="https://electronics.stackexchange.com/questions/102611/what-happens-if-i-omit-the-pullup-resistors-on-i2c-lines">Don't forget the external pullup resistors</a> though, on SDA and SCL.</p>
