8.2. Instructions

Reading a resistive touch screen accurately is not quite as straightforward as it first sounds because, despite what you may have read online in various Arduino forums and blogs, they don't have specific output connections for X and Y values. You can't read both the X and Y axis simultaneously: you have to set up the pins in one configuration to read the X value, and change them to another configuration to read the Y value. In practice, this can be done so fast that there is no way the user can tell you're not reading both the X and the Y value at the same time.

Once you understand the physical structure of a touch screen you'll realize why they don't have simple connections for power, ground, X, and Y, as many people claim.