Multifunctional CNC waveform generator circuit diagram

The multifunctional CNC waveform generator circuit is shown in the figure below. It is a practical digital waveform generator circuit that can generate triangle waves and sawtooth waveforms . In the figure, two 4-bit reversible counters SN74L191 are connected in series to form an 8-bit reversible counter. The output of the up or down count is used as the input of the D/A converter, and its output voltage Vo also gradually increases or decreases, changing linearly. When the manual switch S3 is moved to the "2" position, the flip-flop output Q=1, the counter counts down and outputs a negative sawtooth wave; when S3 is moved to the "3" position, Q=0, a positive sawtooth wave is generated; When S3 is moved to the "1" position, Q flips repeatedly between 0 and 1, generating a triangle wave.