Solution to jitter of key switch

 

The key switch can be used in many places and fields, and it can be seen everywhere in our life, but there will be some problems of jitter when it is used. This problem may bother us for a long time. Today, we will solve this problem for you.

Is there any way to prevent the jitter of the key switch of the single chip computer?

Because of the inherent physical characteristics of the machine, the key switch jitter of the single chip computer will rebound mechanically when it contacts instantaneously, resulting in unstable signal in 2-8 milliseconds. Solution: Software delay de-jitter (actually a neglect) and hardware de-jitter software judgment: switch closure - delay - or closure? —— If it is decided to open, software solution can reduce the cost, but sometimes hardware degradation beyond the scope of the delay will cause failure. Hardware Solution: A dedicated de-jitter chip or self-assembled bistable de-jitter circuit is two RS flip-flops composed of non-gates.

AD keys refer to the use of analog-to-digital conversion method to get the key value, which greatly saves the number of ports compared with matrix keys and independent keys, because a port can input hundreds to thousands of keys.

First, talk about your non-mechanical buttons, cost is the biggest problem, for large-scale production, even save a resistance is good, and the cost of software can be neglected, compared with teaching, the boss will definitely choose a low cost. The boss also knows that technology can get around it, but compared with cost, everything is floating clouds.

Besides, this anti-jitter function can be used not only on keys, but also in signal acquisition and data communication. You can't install a high-performance interface for every IO port. For microcontrollers, is the keyboard really not the key, PA port can be used to prevent shaking, PB port can not be used?

Finally, for the end user how to use the keyboard, how to operate habits, developers simply can not control, nor should they control, since it can not change the user, it can only change themselves.

This is the explanation of the jitter problem of the key switch. Please pay attention to these problems.