Mechanical switch debounce circuit

Abstract

The invention discloses a mechanical switch jitter elimination circuit. The mechanical switch jitter elimination circuit comprises a switching pulse generating circuit, a controllable discharging circuit, a controllable charging circuit, a capacitor and a Schmidt circuit. Output pulses of the mechanical switch jitter elimination circuit are used for controlling the controllable discharging circuit and the controllable charging circuit through a three-state gate; one path is selected to perform discharging or charging on the capacitor through switching pulses; and a signal on the capacitor is processed through the Schmidt circuit to obtain output pulses. Through adoption of the mechanical switch jitter elimination circuit, positive narrow pulse interference at a negative wide pulse period and negative narrow pulse interference at a positive wide pulse period can be filtered automatically, and in particular continuous key contact jitter narrow pulse interference signals can be filtered. The maximum widths of positive narrow pulses and negative narrow pulses needing to be filtered can be adjusted through change of a charging time constant and a discharging time constant respectively. The mechanical switch jitter elimination circuit can be applied to occasions on which mechanical switch pulse jitter influences need to be eliminated reliably through a circuit.

Description

technical field [0001] The invention relates to a pulse signal processing circuit, in particular to a mechanical switch debounce circuit. Background technique [0002] In the digital signal circuit, it is often required to output the corresponding switch signal or pulse signal when the mechanical switch is operated. When the mechanical switch is closed or disconnected, the switch pulse will generate a jitter interference pulse due to the jitter of the contact. Using software to eliminate switch jitter needs to consume CPU working time, which greatly wastes system resources. When it is necessary to use a circuit to eliminate the influence of switch jitter pulses, the commonly used methods are RS flip-flop and RC filter circuit. When RS flip-flop is used, the switch is required to have both a normally closed switch and a normally open switch, and its application is limited. When the RC filter circuit is used, when the jitter interference is continuous narrow pulse interfere...

AI Technical Summary

Problems solved by technology

When using the RS flip-flop, it is required that the switch has both a normally closed switch and a normally open switch, and its application is limited

When the RC filter circuit is used, when the jitter interference is continuous narrow pulse interference, the filter time constant needs to be increased to affect the rapid response capability of the circuit; or when there is continuous narrow pulse interference in the mechanical switch pulse circuit, the RC filter circuit has DC memory Effect, the previous narrow pulse will affect the filtering of the latter narrow pulse

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