Touch Panel Driver
The objective of the project is to design a driver for a touch panel such that it takes the inputs from the touch panel and responds accordingly as per the input performing the action given to it.
A touch panel is a display which can detect the presence and location of a touch within the display area. The term generally refers to touch or contact to the display of the device by a finger or hand. Touch panel can also sense other passive objects, such as a stylus. However, if the object sensed is active, as with a light pen, the term touch panel is generally not applicable. The ability to interact directly with a display indicates the presence of a touch panel. The touch panel has two main attributes. First, it enables you to interact with what is displayed directly on the screen, where it is displayed, rather than indirectly with a mouse or touchpad. Secondly, it lets one do so without requiring any intermediate device, again, such as a stylus that needs to be held in the hand. Touch panels are of different types some of them are resistive touch panel surface acoustic wave touch panel capacitive touch panel etc. A resistive touch panel is composed of several layers. The most important are two thin metallic electrically conductive and resistive layers separated by thin space. When some object touches this kind of touch panel, the layers are connected at certain point; the panel then electrically acts similar to two voltage dividers with connected outputs. This causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. A capacitive touch panel is coated with a material, typically indium tin oxide, that conducts a continuous electrical current across the sensor. The sensor therefore exhibits a precisely controlled field of stored electrons in both the horizontal and vertical axes - it achieves capacitance. The human body is also an electrical device which has stored electrons and therefore also exhibits capacitance. Capacitive sensors work based on proximity, and do not have to be directly touched to be triggered. It is a durable technology that is used in a wide range of applications including point-of-sale systems, industrial controls, and public information kiosks. It has a higher clarity than Resistive technology, but it only responds to finger contact and will not work with a gloved hand or pen stylus. Capacitive touch screens can also support Multitouch. A good example of this is Apple Inc.'s iPhone and iPod touch.
The system consists of a microcontroller which is responsible for the input data scanning and also for the generation of output signals for the control devices, touch panel which senses the object coming in contact with it, control devices such as relay etc. The microcontroller is connected with the touch panel through the port pins when the power is switched on the microcontroller starts scanning the input ports to check whether a object is in contact with the touch panel when an object comes in contact with the touch panel, it sends the location of the object through the output pins and this is scanned by the microcontroller upon scanning the microcontroller will get a location on the touch panel and depending on the point of contact the microcontroller generates output signals to the powered devices connected to the microcontroller through a relay thus we can control the powered devices by touch panel.
Such displays can be attached to computers or, as terminals, to networks. They also play a prominent role in the design of digital appliances such as the personal digital assistant (PDA), satellite navigation devices and mobile phones. Touch panels are popular in heavy industry and in other situations, such as museum displays or room automation, where keyboards and mouse do not allow a satisfactory, intuitive, rapid, or accurate interaction by the user with the display's content.