Computer Software-Controlled LED Matrix

The project was made using a software from computer that can be used to control less than 12 outputs of parallel port with the addition of more components to control more than 12 LEDs.

The LEDs will be addressed individually by sending a series of pulses of information. The display utilizes two 5×7 LED consisting of 10 columns and 7 rows for a total of 70 LEDs. The matrix works on the basis of scanning the display very quickly and the switching between the columns is done using the 4017 chip. The chip sequentially activates 1 of 10 of the other pins when a signal is sent to a certain pin.

The chip takes its command to switch one column high from the software that makes the parallel port turn ON the individual LEDs in the required column. This procedure is done very quickly in fast frequency.

There are 10 transistors and 10 resistors required for this project, which should be soldered with appropriate spacing. The parallel port will send a signal to the transistor that acts as a switch for the external power supply to provide the current needed to light the LEDs.

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