These were originally built for AT&T and can be found from several sources (e.g. EarthLCD). Please note, however, that the original AT&T firmware must be replaced in order to use these displays in your project and depending on where you get your panel, the firmware may or may not have already been replaced.

My panels have had the original AT&T firmware replaced with the excellent code provided by PJRC which implements an easy to use serial interface running at 19,200 baud. The firmware offers a command set based on that of the widely used Hitachi HD44780 controller making it easy to integrate into your project. A .zip file with all the files needed to build the PJRC firmware as well as a .hex file containing the compiled firmware is available here. See this page for command set details. A connection diagram for external switches supported by the firmware may be seen here.

The interface is RS-232 format with regard to timing (19,200 baud, 8 bits, no parity, 1 stop bit) but the Rx and Tx signals are TTL level, positive logic. The panel requires +5V at about 70mA for the main logic and a negative voltage for the contrast control, -9 to -12 volts at about 2mA. This is often supplied by a MAX232 chip if you don't already have a suitable negative supply in your design.

Some sample code for driving the display from a BasicX microcontroller may be found here. A page describing an application using the panel with links to schematics showing it connected to a BX-24 may be found here. A display screen from that application appears below.

The panel has a 17-pin connector on the back, with approximately 1.5mm pitch, to which connections may be made with hookup wire or ribbon cable. Here is a picture of a 20 conductor ribbon cable locked into the connection. The connector has two interlocking plastic pieces. You pull up the moveable piece which releases pressure on the internal connectors and slide in your wires. When you press the moveable piece back down it secures the wires in place.

Below are photos of the built-in font characters. Each font has two photos - one showing characters 0 to 127 and the other showing characters 128 to 255.