Use printer port as programmable frequency generator

摘要

Asimple and inexpensive circuit (Figure 1) and a simple C program (Listing 1) are all you need to turn your PC's printer port into a programmable frequency generator. Using a few low-cost and readily available components, the circuit occupies little space and is easily attachable to the printer port. The circuit has advantages over a 555-based astable multivibrator in that it eliminates the tedious task of adjusting a potentiometer while you watch a frequency counter or oscilloscope.