Analysis touchscreen hops

Took over a touch screen bug, touch screen occasionally occur hops, four-wire touch screen, pmic13892 sampled including coordinates and contact-resistance

Assumed that contact-resistance maximum and minimum, respectively resist_max, resist_min

After observed hops occur in two situations:

1 Using the stylus, nail tip and other hard objects leaving the screen the moment will occur hops, hops occur when the contact-resistance sample values ​​greater than resist_min, and less than resist_max

2 Use the belly occur frequently hops, then contact-resistance sampled value is greater than resist_min, less than resist_max, coordinate sampling value is very accurate, and a wide range of hops occur frequently

In the first case, can indeed be filtered to drive the contact-resistance of the sample data is not correct

But for the second case, it can be concluded that pmic or touch screen hardware problem, the software can not the perfect solution

There are many online correction algorithm, in fact, think many of them are irresponsible, first find the root of the problem is not trying to pass another set of problems botched correction algorithm

The resulting impact on performance

I encountered another problem touchscreen, touch sampled sound playback effect, this typical hardware requires software to circumvent the problem is, in fact, only minor modifications to the lower end hardware

To solve the hops 

Sometimes clumsy approach can temporarily solve the problem quickly, but you can never lose the opportunity to know the truth