Key switch buffeting elimination circuit used for GPIO interface

Abstract

The invention discloses a key switch buffeting elimination circuit used for a GPIO interface. The buffeting elimination circuit comprises a charge circuit, a discharge circuit and a capacitor. When akey switch is in an un-pressed state, the discharge circuit is in an off state, and the charge circuit charges the capacitor; when the key switch is in a pressed state, the discharge circuit signallydischarges electric quantity of the capacitor through the key switch, and the charge circuit is bypassed to the signal through the key switch; besides, the buffeting elimination circuit further comprises a buffer which is used as a reshaping circuit, and the buffer is used for reshaping voltage waveforms at the two ends of the capacitor, and therefore, the GPIO interface obtains a switch signal with good waveform quality. The buffeting elimination treatment disclosed by the invention does not need to occupy processor or controller resources, and the buffeting elimination circuit is simple in structure, is stable and reliable in work, and has a very good buffeting elimination effect.

Description

technical field [0001] The invention relates to a key switch debounce circuit for a GPIO interface. Background technique [0002] In the circuit design and development of embedded systems, the GPIO (General Purpose Input Output) interface of the processor or controller is often used to detect external input switch signals such as key switch signals as reset (reset) signals, recovery The factory setting signal, mode switching signal, etc. realize related functions. Such as figure 1 As shown, at the moment of pressing the mechanical key switch, several millisecond-level jitter signals will be generated due to mechanical jitter (see figure 1 The jitter signal of the middle button), when the hardware debounce processing is not performed, the jitter signal becomes several switch signals after passing through the GPIO interface with digital circuit characteristics (see figure 1 In this case, if such a switching signal is directly used to perform subsequent operations, multiple ...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to overcome that the software debounce program in the prior art needs to occupy resources, while the RC filter circuit in the hardware debounce circuit has a simple structure but the debounce effect is general, and the steady state circuit has a good debounce effect but the structure Complicated defects, providing a key switch debounce circuit for GPIO interface

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