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Reading data off LT3582 with I2C interface



		

			

									
					    Hdiieolend
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jul 29, 2021 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,

    I'm trying to read a byte of data off an LT3582. I'm able to program the 4 internal registers just fine and get the expected voltages on the out pins, the only problem I'm getting is when I try to read a byte after I program it. After setting the SDA pin on my master to high Z, the line idles until the master takes control of it again. In the screen shot, the data I expect to be getting is 01000111 (the 0100 would be visible if it was working). 
    

     
    

    

    I'm using an nRF52840 DK (https://www.nordicsemi.com/Products/Development-hardware/nrf52840-dk) as my master and a Boost-INV click as the platform for the LT3582 (https://www.mikroe.com/boost-inv-click)
    

    Additionally, the table at the bottom of the screen shot is from the LT3582 datasheet (https://www.analog.com/en/products/lt3582.html), where grey boxes denote bits that the slave is sending. Is there a reason the data byte isn't grey or was this an oversight?
    

    Thanks!
    
									
			        
		
    

				
						
        

    
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Aug 3, 2021 5:18 AM
            
            
					
      
	
      

		
		
      
					
      Hi Hdiieolend,
      

      

      Prior to the Data lines becoming idle, the last ACK bit has somewhat a strange behavior.
      

      It is not fully held low and instead is at approximately around 1V or greater.
      

      Not sure if this is consistent or this only happens when the Data Line becomes idle.
      

      

      Here are some of my questions to have a better idea on this behavior.
      

      

      1. What is the pull-up voltage, pull-up resistor on I2C data lines?
      


      2. How often do you encounter the problem on reading via I2C? Is it consistent every time?
      


      3. Have you tried other clock frequency for ex, 50kHz, 100Khz?
      


      4.  Can you pls share a scope capture of the a successful read sequence?
      

      

      For your question: 
       
      Additionally, the table at the bottom of the screen shot is from the LT3582 datasheet (www.analog.com/.../lt3582.html), where grey boxes denote bits that the slave is sending. Is there a reason the data byte isn't grey or was this an oversight? 
       
            >>> Yes, I agree this should be gray since the data is coming from the slave.
      

      

      Regards,
      

      

      Elias
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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													0
							
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Aug 3, 2021 5:18 AM
            
            
					
      
	
      

		
		
      
					
      Hi Hdiieolend,
      

      

      Prior to the Data lines becoming idle, the last ACK bit has somewhat a strange behavior.
      

      It is not fully held low and instead is at approximately around 1V or greater.
      

      Not sure if this is consistent or this only happens when the Data Line becomes idle.
      

      

      Here are some of my questions to have a better idea on this behavior.
      

      

      1. What is the pull-up voltage, pull-up resistor on I2C data lines?
      


      2. How often do you encounter the problem on reading via I2C? Is it consistent every time?
      


      3. Have you tried other clock frequency for ex, 50kHz, 100Khz?
      


      4.  Can you pls share a scope capture of the a successful read sequence?
      

      

      For your question: 
       
      Additionally, the table at the bottom of the screen shot is from the LT3582 datasheet (www.analog.com/.../lt3582.html), where grey boxes denote bits that the slave is sending. Is there a reason the data byte isn't grey or was this an oversight? 
       
            >>> Yes, I agree this should be gray since the data is coming from the slave.
      

      

      Regards,
      

      

      Elias
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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