LCD Terminal Hardware

Brief

The LCD Terminal are using a PIC16F628 to control the 40x4 LCD module.
A MAX232 chip are used to convert the RS-232 signal to TTL level.
Not like the design of my MO-LCD project, It can select to use a var-resistor or software to adjust the LCD's contrast. The software controled contrast are using 16F628's PWM output feature. Which connect to a RC network to control the contrast voltage. It is not so importent feature, just for experiment.

Following is the main component used:

• Microchip PIC16F628 MCU IC
• MAX232 IC
• LM7805 IC(Only needed if you want to use the external power)
• a 40x4 LCD

Schematic

The circuit are quite simple, you can click here to view the schematic in pdf format.
You can also also click here to download the design file in Protel99 format.

PCB Layout

Here is my PCB Layout in PDF:

• Top Layer
• Bottom Layer
• Silk Overlay

For your convenes, I also provide the PCB Layout in Protel99 SE format so that you can easily modify it to match your needs. 
Click here to download.