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ADT7420 Incorrect DeviceID



		

			

									
					    Grenna1
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on May 20, 2022 
				
			
			
		
    

				
		
    
		    		    
		    
		    		            		        
    Category: Software
    
    		        		            		    
    Product Number:  ADT7420 
    
    		        		        		        
    Software Version: NA
    
    		    		    	
			
    Hi,
    

    

    May I ask if there's any available program for ADT7420? A snippet will do. I am trying to read registers (using I2C), but it seems like I'm getting incorrect default value. Maybe there's something wrong with my code in reading registers? Can anyone help me about it? Thank you.
    

    

    e.g Trying to read device ID
    

    

    Wire.beginTransmission(0x48);
    

    Wire.write(0x0B); // register to read the device ID
    

    Wire.endTransmission();
    

    Wire.requestFrom(0x48,1); //1 byte since Device ID is 1byte
    

    x = Wire.read();
    

    Serial.print(x,hex);
    

    I am getting a value of 0x0D from the 0x0B register which is the device ID but it should be 0xCB;
    

    

    -Grenna
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		






			

			
    
			
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      •  Analog Employees  
      
				
						
						                        
                                                
                        
                                                	 Jun 10, 2022 
						
										
						
												+1
													
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      Hello  ,

      What you're actually reading is the value at the default address of the pointer register (0x00). This is caused by the lack of a repeat start after writing the register to be read to the…
      
				
			
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      •  Analog Employees  
      
            
			                            
                        
                on May 25, 2022 6:39 AM
            
            
					
      
	
      

		
		
      
					
      Hi Grenna,
      

      Reading back data from the configuration registers should look like this. 
      

      Checking your code, the address and register byte are correct. Please double check if your are not violating any timing specs. 
      

       
      

      

      Regards,
      

      Mae
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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													+1
							
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
			                            
                        
                on Jun 10, 2022 4:56 AM
            
            
					
      
	
      

		
		
      
					
      Hello  ,

      What you're actually reading is the value at the default address of the pointer register (0x00). This is caused by the lack of a repeat start after writing the register to be read to the address pointer register. To correct this, you simply have to implement a repeat start after sending the Wire.write(0x0B) line. If I'm not mistaken that you're implementing this on an arduino, you can do the correction by simply changing the Wire.endTransmission() line to Wire.endTransmission(false). 

      

      Regards,

      Karlo 
      
			
      

		
		
		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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