Resistive Touch Screen Arduino project

Resistive Touch Screen Arduino project 


Interfacing Resistive Touch Screen to Arduino :

First we must  know about the basic arduino programming 

Arduino Software

Software programs, called sketches, are created on a computer using Arduino integrated
development environment ie. (IDE). The IDE enables you to write and edit code
and convert this code into instructions that Arduino hardware can understand and execute. The IDE
also transfers those instructions to the Arduino board (a process called uploading).

Arduino Hardware

The Arduino board is where the code you write will be executed. The board can only control
and respond to electricity or current, so specific components are attached to it to enable it to
interact with the real life world. These components can be sensors, which convert some of 
aspect of the physical world to electrical singals so that the board can sense it, or actuators,
which get electricity from the board and converts it into digital or analog singnals something that changes the way we deal with the world.

Examples of sensors include switches, accelero meter, and ultrasound distance
sensor. Actuators are things like lights and LEDs, speakers, motors, and screens or displays.
There are a variety of official boards that you can use with Arduino and a wide
range of Arduino compatible boards (mounts) produced by members of the community.
The most popular method is a USB connector that is used to provide the power and the
connectivity for uploading your software onto the board. 

You need to install the Arduino development environment on your computer.
and can be found on arduino website or use this link.

Lets get started

           Resistive touch screens all work in same way, so this interface would (probably ) work fineacross all or many different touch screens available. Just make sure you have the datasheets for your screen in case there is any doubt about how it works or what are connections.

Resistive Touch Screen Arduino project

Resistive Touch Screen Arduino project

1 Principles of Operation

1.1 Resistive Touch-Screen Concept

A resistive touch screen is constructed with two transparent layers coated with a conductive material stacked on the top of each other. When pressure is applied by a finger or using a stylus on the screen, the top layer makes the contact with the lower layer. When a voltage is applied across one of the layers,  voltage divider is created. 

The coordinates of a touch screen can be found by applying a voltage across one layer in the "Y" axis direction and reading the voltage created by the voltage divider to find the "Y" coordinate, and then applying voltage across the other layer in "X-axis"  direction and reading the voltage created by the voltage divider to find "X" coordinate.

Detecting a Touch

Now ,To know if coordinate readings are valid or not , there must be a way to efectively detect whether the screen is being touched or not. This can be done by supllying a positive voltage (VCC) to "Y+" through a pullup resistor and frounding the "X–". The pullup resistor must be significantly larger than the total resistance of the touch
screen, which is usually a few 100 ohms. When there is no touch, "Y+" is pulled up to the +voltage. When there is a touch, "Y+" is pulled down to ground as shown in Figure 1. 

This voltage level changes can be used to generate a pin-change interrupt.

Resistive Touch Screen Arduino project

Reading a 4-Wire Screen

The x and y coordinates of a touch on a 4-wire touch screen can be read in two steps. First, "Y+" is driven positive , "Y–" is driven to ground or negative,  and the voltage at "X+" is measured. The ratio of this measured voltage to the drive voltage applied  equal to the ratio of "Y" axis  coordinate to the height of the touch screen. The "Y" coordinate can be calculated by this . The "X" coordinate can be similarly obtained by driving
"X+" high, driving "X–" axis to ground, and measuring the voltage at "Y+" axis. The ratio of this measured voltage to drive voltage applied is equal to the ratio of the x coordinate to the width of the touch screen.

This one is very interesting project for beginners 

All the very best with it.


Resistive Touch Screen Arduino project Resistive Touch Screen Arduino project Reviewed by Accrux on January 08, 2017 Rating: 5
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