Scroll text on 8x8 LED Matrix Display using PIC18F4550 and MikroC compiler

Lights and LEDs always fascinate me. In this experiment with 8x8 led matrix display, I have interfaced an 8x8 led matrix without using any external buffer IC to the PIC microcontroller. This saves cost and wiring hassle as well as makes the design simple. PIC microcontrollers can sink and source 20mA through its pins. That's what made me think of eleminating external buffer IC which people normally use when they use other microcontrollers which can not sink and source at 20mA directly.

In this experiment I have used PIC18F4550 because it was already present in my component box. You may replace PIC18F4550 with other PIC mikrocontrollers. The 8x8 LED matrix displays have total of 64 leds which are wired in 8 columns and 8 rows (Please see figure 1). The 8x8 LED Dot matrix display that I used was 2.3" GMC2X88C. I had further made an excel sheet to understand wiring inside this 8x8 (Please see figure 2). Sometimes when you buy an 8x8 led matrix you may not know its manufacture part number (as the part number printed on these matrix sometimes are not searchable and you cant find the datasheet), therefore you may need to find yourself the pin-outs of your led matrix. And that's what I did, I used multimeter to figure out cathode and anodes of the display and later found that my display closely matches Fairchild's Part Number GMC2X88C.

Video

Figure 1:

Figure 2 - 8x8 Led Matrix Pinouts explained in detail:

Schematics:

Pdf copy of the Schematics can be downloaded from here:
8x8_Led_Matrix_Schematics.pdf

Source Code:
C Source Code zip file can be downloaded from here:
LED_Matrix_8x8_timer.zip

The Oscillator settings for this project can be copied from following snapshot of MikroC compiler. PIC18F4550 in this example the PIC microconteoller is running from internal 8.000MHz oscillator. The dialog box can be accessed by pressing Ctrl+Shift+E