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Brightness adjustment on ADV7842-ADV7511 eval kit



		

			

									
						JeffMcD
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on May 16, 2011 
				
			
			
		


				
		

		    		    
		    
		    	
			
I am seeing strange behavior when adjusting the brightness setting on the eval kit.

 
Using either a DVI or analog VGA input, when I enable color adjustments by setting the MSB of CP register 0x3E, and then changing CP register 0x3C, I get unexpected changes in the green intensity. For example, if my input is shades of red only, adjusting the brightness will add in green at the higher values. At lower values only red is visible although brighter than expected. If the input is shades of green, the brightness control works perfectly throughout the range.

 
What am I missing?

 
Thanks,

 
Jeff

								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	

		
	











	

	

					



			








	
	
	
	



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                                 Analog Employees 
                                
                            
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                on May 26, 2011 12:46 AM
            
            
					
    
	
    

		
		
    
					
    Hi Jeff,
    
 
    I was seeing the green tint on the black color bar last week with HDMI.  Today, I ran the same script and then set 0x69=0x14 and 0x3E=0x84 and I don't see any green tint on the black color bar when I set BRIGHTNESS_CNTRL to different values. So the behavior seems to be different.
    
 
    However, with that said, even when I don't set MAN_CP_CSC_EN=1 (i.e. leave 0x69=0x04) and then set 0x3E=0x84, I don't see any green tint on the black color bar when I set BRIGHTNESS_CNTRL to different values. 
    
 
    So maybe something is different in my setup from last week to today. 
    
 
    But I am still seeing this issue when I select VGA as an input regardless of whether I set MAN_CP_CSC_EN to 1 or not.
    
 
    Why don't you test again with DVI/HDMI input and see if you can get brightness to work?
    
 
    -Matt
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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													0
							
			
				
									
							        
            
                                                                                                        
      
                            
    • 
                                 Analog Employees 
                                
                            
      • 
                        
     
                                                           			
			                            
                        
                on May 26, 2011 12:46 AM
            
            
					
    
	
    

		
		
    
					
    Hi Jeff,
    
 
    I was seeing the green tint on the black color bar last week with HDMI.  Today, I ran the same script and then set 0x69=0x14 and 0x3E=0x84 and I don't see any green tint on the black color bar when I set BRIGHTNESS_CNTRL to different values. So the behavior seems to be different.
    
 
    However, with that said, even when I don't set MAN_CP_CSC_EN=1 (i.e. leave 0x69=0x04) and then set 0x3E=0x84, I don't see any green tint on the black color bar when I set BRIGHTNESS_CNTRL to different values. 
    
 
    So maybe something is different in my setup from last week to today. 
    
 
    But I am still seeing this issue when I select VGA as an input regardless of whether I set MAN_CP_CSC_EN to 1 or not.
    
 
    Why don't you test again with DVI/HDMI input and see if you can get brightness to work?
    
 
    -Matt
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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