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320*240 resistive touch screen calibration problem



		

			

									
					    arash.rezaee
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 10, 2012 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi every one.
    
 
    I have 320*240 LCD with resistive touch screen and touch screen controller of AD7843 ( All is together in one LCD from topway: KM2088S). I want to know what is the best way to calibrate the touch screen? when I push the touch screen a little bit it shows me a number, but when I push it harder it shows me a different number!! how can I solve it? Is it going to solve by calibration? I really appreciate if you guys can help me.
    
 
    Regards
    
 
    Arash
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			








	
	
	
	



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      •  Analog Employees  
      
            
			                            
                        
                on Nov 20, 2012 8:05 PM
            
            
					
      
	
      

		
		
      
					
      Hi Arash-
      
 
      I checked with my contact here for resistive touch screen controllers and they provided the following information:
      
 
      I would suggest measuring pressure as well as the X and Y coordinates. This can only be done with the AD7873 but this part is pin-to-pin compatible with the AD7843. Would it be possible to replace the AD7843 with the AD7873?
      
 
      Also, to improve the accuracy of the AD7843, usually, some averaging of the X and Y position is a good idea. The touch screens, due to their mechanical construction, can bounce a bit, so most customers perform some sort of averaging on the result. For the AD7843, the averaging must be done in the host. 
      
 
      Since there is not a specific community on EngineerZone to support this, if you have further questions on this topic, I suggest contacting your local Analog Devices support center listed at http://www.analog.com/support.
      
 
      Regards,
      
 
      AndyR
      
 
      EngineerZone Community Manager
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      
            
			                            
                        
                on Nov 20, 2012 8:05 PM
            
            
					
      
	
      

		
		
      
					
      Hi Arash-
      
 
      I checked with my contact here for resistive touch screen controllers and they provided the following information:
      
 
      I would suggest measuring pressure as well as the X and Y coordinates. This can only be done with the AD7873 but this part is pin-to-pin compatible with the AD7843. Would it be possible to replace the AD7843 with the AD7873?
      
 
      Also, to improve the accuracy of the AD7843, usually, some averaging of the X and Y position is a good idea. The touch screens, due to their mechanical construction, can bounce a bit, so most customers perform some sort of averaging on the result. For the AD7843, the averaging must be done in the host. 
      
 
      Since there is not a specific community on EngineerZone to support this, if you have further questions on this topic, I suggest contacting your local Analog Devices support center listed at http://www.analog.com/support.
      
 
      Regards,
      
 
      AndyR
      
 
      EngineerZone Community Manager
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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