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AD4020 Recommended for New Designs
The AD4020 is a high accuracy, high speed, low power, 20-bit, Easy Drive, precision successive approximation register (SAR) analog-to-digital converter...
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IIO Oscilloscope plot channel display issue with multiple AD4020 devices



		

			

									
					    mbradley
					
							

			
				
									
											
			
			
				
  •  Analog Employees  

			
			
			    	
			                    
                
				                on Jul 17, 2020 
				
			
			
		


				
		

		    		    
		    
		    	
			
Hi there,


I've an FMC board with 4xAD4020 on it, connected to a Zedboard. There seems to be display issue with how the channels of each individual device are shown in the tree. I'd expect one voltage0 channel under each ad4020 node, but they all seem to be grouped under the first ad4020.   This is version 0.99, but I've also seen this the iio scope that ships with the current SD card image.


 


Also, it looks like if I want to save the data for all 4 channels using the 'Save As' feature, I can only do for a single device at a time, I can't enable the voltage0 checkbox for each of the 4 device in the dialog - only one seems to stay active.  Is there a way to save the data for all 4 devices from the GUI?


Thanks now


 

									
			        
		


				
						
        

    
Tags: 
                                            
                 AD4020
                
                                                    
                 Single Channel A/D Converters
                
                                                    
                 Precision A/D Converters
                
                                
            

    
    

		

			
						
									
									
						
						
			
			
			
			
		


        
        

					

			





















	

	

					



			








	
	
	
	



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													+1
							
			
				
									
							        
			
			
			
    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Jul 17, 2020 1:03 PM
            
            
					
    
	
    

		
		
    
					
    Channels will be grouped based on the driver naming. So my guess is that in your device tree you do not have unique names for the individual drivers which have the associated buffered channels. This is why the grouping in IIO-Scope is getting confused.
    

    Note that IIO-Scope cannot capture from multiple drivers simultaneously in the same capture window.
    

    -Travis
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
				
						
						
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Jul 17, 2020 3:56 PM
            
            
												
						in reply to travisfcollins
					
									
    
	
    

		
		
    
					
    Hi Travis,
    

    When you say IIO-scope can't capture from multiple drivers, does that mean that I need to do this from a python script instead?  It does look like I'm getting 4 separate and different channels of data displayed in IIO scope, so do you mean that the data might only be for one channel, just duplicated/offset/sliced in some way that maybe isn't obvious from an initial reivew?
    

    This is what I've got for the 4 ADCs in the devicetree.dts file inside an axi-spi_engine_x instance.  They each have a unique label there, is that what you mean?
    

    ad4020_0: adc@0 {
     compatible = "ad4020";
     <snip>
    

    };
    

    <snip>
    

    ad4020_2: adc@0 {
     compatible = "ad4020";
     <snip>
     };
    

    <snip>
    

    ad4020_3: adc@0 {
     compatible = "ad4020";
     <snip>
     };
    

    <snip>
    

    ad4020_4: adc@0 {
     compatible = "ad4020";
    

    <snip>
     };
    

    I've also put the relevant iio_info output here in case that helps:
    

    iio:device0: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 976412
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
     iio:device1: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 792238
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
     iio:device2: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 21551
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
     iio:device3: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 831778
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
    

    

    Thanks now,
    

    Michael.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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													0
							
			
				
									
							        
			
			
			
    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Jul 17, 2020 3:56 PM
            
            
												
						in reply to travisfcollins
					
									
    
	
    

		
		
    
					
    Hi Travis,
    

    When you say IIO-scope can't capture from multiple drivers, does that mean that I need to do this from a python script instead?  It does look like I'm getting 4 separate and different channels of data displayed in IIO scope, so do you mean that the data might only be for one channel, just duplicated/offset/sliced in some way that maybe isn't obvious from an initial reivew?
    

    This is what I've got for the 4 ADCs in the devicetree.dts file inside an axi-spi_engine_x instance.  They each have a unique label there, is that what you mean?
    

    ad4020_0: adc@0 {
     compatible = "ad4020";
     <snip>
    

    };
    

    <snip>
    

    ad4020_2: adc@0 {
     compatible = "ad4020";
     <snip>
     };
    

    <snip>
    

    ad4020_3: adc@0 {
     compatible = "ad4020";
     <snip>
     };
    

    <snip>
    

    ad4020_4: adc@0 {
     compatible = "ad4020";
    

    <snip>
     };
    

    I've also put the relevant iio_info output here in case that helps:
    

    iio:device0: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 976412
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
     iio:device1: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 792238
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
     iio:device2: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 21551
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
     iio:device3: ad4020 (buffer capable)
     1 channels found:
     voltage0: (input, index: 0, format: le:s20/32>>0)
     3 channel-specific attributes found:
     attr 0: offset value: -1048576
     attr 1: raw value: 831778
     attr 2: scale value: 0.002384185
     1 device-specific attributes found:
     attr 0: sampling_frequency value: 1800000
     3 buffer-specific attributes found:
     attr 0: data_available value: 0
     attr 1: length_align_bytes value: 8
     attr 2: watermark value: 400
     1 debug attributes found:
     debug attr 0: direct_reg_access value: 0x63
    

    

    Thanks now,
    

    Michael.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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