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ADV7282 Not Recommended for New Designs
The ADV7282 / ADV7282-M are versatile one-chip, multiformat video decoders. The ADV7282 / ADV7282-M automatically detects standard analog baseband video...
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About the cause of vertical synchronization shift in ADV7282



		

			

									
					    Kazuhiko
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on May 9, 2023 
				
			
			
		
    

				
		
    
		    		    
		    
		    		            		        
    Category: Software
    
    		        		            		    
    Product Number:   ADV7282 
    
    		        		    		    	
			
    

    Hi,
    

    Please tell me about ADV7282.
    

    A video signal is input and the output result is monitored.
    The image scrolls up and down as if there is a vertical sync shift under certain conditions.

    Even if you compare the video signal waveforms (with / without an event), there is no difference in the waveforms and the cause cannot be understood.
    

    Could you please tell me under what conditions vertical synchronization deviation occurs?
    

    For certain conditions, the details are as follows:
    

    [conditions]
    The input camera video signal is 2ch (black and white, color).
    In addition, the cameras (2 units) are installed on a table driven by a servo motor.
    Scrolling up and down the image occurs under the following specific conditions.
    (Also, it occurs only in black and white.)
    

    [Specific conditions]
    -When the drive power supply (servo motor) is started and the camera is switched (color → black and white), the image scrolls up and down.
    -When the drive power supply (servo motor) is started and the camera is switched (black and white → color), no event occurs.
    -When the drive power supply (servo motor) is turned off, no event occurs even if the camera is switched (color → black and white, black and white → color).
    -Even if the drive power supply (servo motor) is started with the camera (black and white) fixed, no event occurs.
    -Even if the drive power supply (servo motor) is turned off while the image is scrolling up and down, the image remains scrolled up and down.
    


    [Acquired waveform]
    The NTSC waveform (the input part to the board and the enlargement of the vertical synchronization part) is attached. (Normal, when an event occurs)
    

    ・Normal
    

     
    

    

    ・Event Occurs
    

     
    

    Best Regards,
    

    kazuhiko
    

    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      •  Super User  
      
            
			                            
                        
                on May 10, 2023 12:16 PM
            
            
					
      
	
      

		
		
      
					
      Hi,
      

      Please ensure with below things,
         - Vertical scrolling implies the chip is not able to lock to Vsync. Make sure the input wave form is correct and the right amplitude.
      

        - Make sure with the camera that you are using could have a low refresh rate etc. Could you connect this camera directly to a television to see if you still see the issue. Note please turn off advanced features in the TV such as 3D comb etc. Could you try another CVBS source e.g. DVD player.
        - Please read and share User map registers 0x10, to 0x13.
      

        - In NTSC mode the ADV7280-M outputs a 60 Hz field rate. Does your screen match this or is it 50 Hz ? This may also cause jitter video. 
        - Also note that when the BT.656-4 bit equals 0 (default), the ADV728x-T outputs video that is compatible with the ITU-R BT.656-3 standard. When the BT.656-4 bit equals 1, the ADV728x-T outputs video that is compatible with the ITU-R BT.656-4 standard. For more information Please refer "Output Video Format" section .
      

      For example, if the receiver is expecting ITU-R BT.656-4 and ITU-R BT.656-3 is being output from the ADV728x then this can cause abnormal result in the screen, So could you please try toggling the BT656-4 bit (User Map, Register 0x04 bit [7]).
      

      

      Thanks,
      

      Poornima
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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