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The AD1939 is a high performance, single-chip codec that provides four analog-to-digital converters (ADCs) with differential input, and eight digital-to...
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Specified triangle wave on EZ-KIT 21469

		
	
				

			

									
					    Skaucik
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 24, 2014 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
		    			
    
			    
    Hi guys!
    
 
    I have ADSP 21469 EZ-KIT board and i my task looks like thise.
    
 
    During each samples period ( 44.1 kHz) i make interpolation (x8) and want to generate triangular wave 352.8 kHZ and count time when line which go through two next samples and cut triangle wave.
    
 
    How to generate triangle wave: is there specified tool (like function) to create triangle wave with specified period?
    
 
    Is it right way witch i'm thinking?: If i generate 8 period of triangle wave in whole period of 44.1 kHZ i get triangle wave in 352.8 kHz?
    
 
    I think that i should do math for equation of each section next samples and do math for equation of rising and falling edge triangle wave, and using crossing points equation i would get solve, am i right?
    
 
    Please is there any way to solve this?
    
 
    Thanks for your time!
    Michał
    
			
    
			
									
		                             
                        

    
    
                                            
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      •  Analog Employees  
      •  Super User  
      
            
						
                            
            
            				
            
                on Dec 1, 2014 1:29 PM
            
            
						
			            		
      
		
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      Hello Michal,
      
 
      The big problem I see is that you are so beyond the Nyquist frequency that you will not be able to reproduce this wave. I think what you are trying to do is have points on the waveform being sampled at 44.1 kHz rate and then interpolate the points in-between to produce the 352.8 kHz triangular wave. A linear interpolation would certainly work. However, how do you propose to output this waveform into analog? You would need a converter capable of 705.6 kHz fs and then it will only be two samples per period. It will not be a very good representation of the waveform. So to fix this you are looking at an fs of several MHz to reproduce this waveform. You probably should talk to the engineers in the High Speed Converter group. Here is the location of their forum: High-Speed DACs
      
 
      As far as your question about the correct way of calculating this function I will defer again to the DSP group. Processors and DSP
      
 
      Thanks,
      
 
      Dave T
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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      •  Analog Employees  
      •  Super User  
      
            
						
                            
            
            				
            
                on Dec 1, 2014 1:29 PM
            
            
						
			            		
      
		
										0
					
	
      

		
		
      
		
      
                                
                                                            
      
					
      Hello Michal,
      
 
      The big problem I see is that you are so beyond the Nyquist frequency that you will not be able to reproduce this wave. I think what you are trying to do is have points on the waveform being sampled at 44.1 kHz rate and then interpolate the points in-between to produce the 352.8 kHz triangular wave. A linear interpolation would certainly work. However, how do you propose to output this waveform into analog? You would need a converter capable of 705.6 kHz fs and then it will only be two samples per period. It will not be a very good representation of the waveform. So to fix this you are looking at an fs of several MHz to reproduce this waveform. You probably should talk to the engineers in the High Speed Converter group. Here is the location of their forum: High-Speed DACs
      
 
      As far as your question about the correct way of calculating this function I will defer again to the DSP group. Processors and DSP
      
 
      Thanks,
      
 
      Dave T
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

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