The EDP-I has been designed for evaluating LCD modules without having to lay out your own
design. It provides pinouts for the most popular modules in the industry and a standard keyboard
interface. It will interface to most modules that use the industry-standard HD44780 controller (or
equivalent), running in 7-bit mode.
Just plug in a standard AT style keyboard and the LCD module of your choice. The built-in line
editor will give you complete control over the display, including contrast and backlighting.
IMPORTANT NOTES: If your module generates a negative voltage for contrast control,
you MUST ensure that J1 is removed from the EDP-I!
It has been our experience that most
modern modules do not require a negative voltage for contrast until the temperature reaches -30
C. Therefore, the EDP-1 does not directly support Vee and we recommend that most evaluations
be done with standard modules. If you want to connect the Vee from your module you will need
to use external wires and a separate potentiometer.
Backlight Current:
Before connecting a module be sure to read the section on Backlight
Current. Failure to due so could shorten the life of your backlight to only a few seconds!
The EDP-I provides 5 pinouts to support a variety of modules. However, it will only drive one
module at a time.
Please review the following descriptions and ensure that your board is properly configured. The
locations of the various connectors are shown below looking at the top of the board (the keyboard
and power connectors are on the bottom).
Top of board:
T1, L1, L2, B1, B2:
pinouts for mo st
standard LCD m odules. See the following
sections for details.
Aux1 and Aux2:
access to I/O pins
R14:
optional current limiting resistor.
A, K:
pad s for co nnec ting the b ackligh t.
+5Vdc and ground
: additional power
connectio ns.
Bottom of board:
H 1
: connects backlight terminal ‘K’ to the
curre nt con trol ciruit.
H2:
bypasses the current limiting resistor
Vo:
conn ects the c ontra st contro l circuit to
the contrast input on the module.
J1:
connects the modules ‘A’ backlight
terminal to +5 VDC.
