Check whether finger is still on the screen. If not, we couldn't determine where the user has touched. It's better to return early rather than give garbage values.
A more sensitive solution might be caculate the position once the interrupt occured. But it's not anti-shake friendly.
git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1789 bbd45198-f89e-11dd-88c7-29a3b14d5316
The old code only checks touch->max_x > touch->min_x but not touch->max_x == touch->min_x. Thus may lead to divided by zero error.
git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1782 bbd45198-f89e-11dd-88c7-29a3b14d5316
The old code forgot to drop the MSB in the very first byte retrieved from ads7843 after a control byte. This will lead to data corruption especially in 16-Clocks per conversion mode.
git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1781 bbd45198-f89e-11dd-88c7-29a3b14d5316
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