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AD1940 Production
The AD1940 / AD1941 are a complete 28-bit, single-chip, multi-channel audio SigmaDSP™ for equalization, multiband dynamic processing, delay compensation...
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Developing Sigma DSP Cluster

		
	
				

			

									
					    JeanFernandes
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jun 29, 2009 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
		    			
    
			    
    Hi sirs
    
 
    First, I 'm searching for people that uses the Sigma DSP (I trying to use AD1940).
    
 
    My first project is to develop a AD1940 cluster to perform and audio routing system (with some improved features).
    
 
    The basic project concept is :
    
 
    http://jeanfernandes.com/files/images/dspsigmaex.pdf
    
 
    The idea is to put all of them on same board.
    
 
    Some questions:
    
 
    a) Is it possible to wire the Audio Input Codec (as master) on 6 DSP without glue logic ?
    
 
    b) And about the Master Clock ? Usually I use a hibrid square wave clock up to 3 chips. What glue logic is really necessary to
    
 
    this project ?
    
 
    c) Is it possible to draw the board just using 2 layers ?
    
 
    d) I need to put audio compressor on all inputs and I saw that the curve has 32 points, but I dont know how to map an HMI user interface
    
 
    to control all points of this block. My boss suggest me annotate several curves and list them to user choose (its a simple manner but ....)
    
 
    e) If I use the TDM channel (to simplify design) what the maximum sampling rate (I suppose that is 48 Khz).
    
 
    f) I will develop the controller firmware using C (ARM7). Does anyone has an SDK to control the IC's 1940 and 1939 (using SPI) ?
    
 
    Regards
    
 
    Jean Fernandes
    
 
    Using Eval Mini AD1940 Evb to test.
    
			
    
			
									
		                             
                        

    
    
                                            
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                 SigmaDSP Audio Processors
                
                                
            
    
    
    
		
    

				
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Oct 28, 2009 6:13 PM
            
            
						
			            		
      
		
										0
					
	
      

		
		
      
		
      
                                
                                                            
      
					
      Hi Jean,
      
 
      The compressor table has 33 points, which matches the 33 points on the GUI. By changing a big blue point, you can change the overall curve. The big blue points are more like "overlays" as they simply alter the curve of the small blue points behind them.
      
 
      The calculation is actually done using 34 points stored in RAM. The first point stored in RAM represents the gain reduction value for any input below -90dB.
      
 
      Here's an example: A compressor with a threshold of -6dB and a ratio of 2:1.
      
 

      The table is as follows:
      
 
      
  
      
   
    
    
   
    
    
   
    
      
     Point
     dB input
     Output Gain
    
      
    
      
     1
     -90
     1
    
      
    
      
     2
     -87
     1
    
      
    
      
     3
     -84
     1
    
      
    
      
     4
     -81
     1
    
      
    
      
     5
     -78
     1
    
      
    
      
     6
     -75
     1
    
      
    
      
     7
     -72
     1
    
      
    
      
     8
     -69
     1
    
      
    
      
     9
     -66
     1
    
      
    
      
     10
     -63
     1
    
      
    
      
     11
     -60
     1
    
      
    
      
     12
     -57
     1
    
      
    
      
     13
     -54
     1
    
      
    
      
     14
     -51
     1
    
      
    
      
     15
     -48
     1
    
      
    
      
     16
     -45
     1
    
      
    
      
     17
     -42
     1
    
      
    
      
     18
     -39
     1
    
      
    
      
     19
     -36
     1
    
      
    
      
     20
     -33
     1
    
      
    
      
     21
     -30
     1
    
      
    
      
     22
     -27
     1
    
      
    
      
     23
     -24
     1
    
      
    
      
     24
     -21
     1
    
      
    
      
     25
     -18
     1
    
      
    
      
     26
     -15
     1
    
      
    
      
     27
     -12
     1
    
      
    
      
     28
     -9
     1
    
      
    
      
     29
     -6
     0.99
    
      
    
      
     30
     -3
     0.85
    
      
    
      
     31
     0
     0.71
    
      
    
      
     32
     3
     0.6
    
      
    
      
     33
     6
     0.51
    
      
         
  
      
 
      
 
      Note that at an input of -6dB (the threshold), the output = input (well, it's 0.99, but close enough).
      
 
      At 0dB, the output is 0.707, or -3dB.
      
 
      At 6 dB, the output is 0.51, or -6dB.
      
 
      You can make your own curves and calculate the parameters in manually if you prefer.
      
 
      In the GUI, the maximum ratio achievable is limited. However, you can enter in your own parameter data (or right click on a blue point and choose "Set Point Value" to bypass this limitation.
      
 
      You are correct, the x values are always in 3 dB spacings.
      
 
      The new "Standard RMS Compressor" has now been released - Check the toolbox under Dynamics Processors > RMS > Standard Resolution > Lower Range.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

      • 

	
    



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    • 
	
      



	
		
	
	



      
	
      
		
      
							
					
      
		
      
		    
		    		    
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Oct 28, 2009 6:13 PM
            
            
						
			            		
      
		
										0
					
	
      

		
		
      
		
      
                                
                                                            
      
					
      Hi Jean,
      
 
      The compressor table has 33 points, which matches the 33 points on the GUI. By changing a big blue point, you can change the overall curve. The big blue points are more like "overlays" as they simply alter the curve of the small blue points behind them.
      
 
      The calculation is actually done using 34 points stored in RAM. The first point stored in RAM represents the gain reduction value for any input below -90dB.
      
 
      Here's an example: A compressor with a threshold of -6dB and a ratio of 2:1.
      
 

      The table is as follows:
      
 
      
  
      
   
    
    
   
    
    
   
    
      
     Point
     dB input
     Output Gain
    
      
    
      
     1
     -90
     1
    
      
    
      
     2
     -87
     1
    
      
    
      
     3
     -84
     1
    
      
    
      
     4
     -81
     1
    
      
    
      
     5
     -78
     1
    
      
    
      
     6
     -75
     1
    
      
    
      
     7
     -72
     1
    
      
    
      
     8
     -69
     1
    
      
    
      
     9
     -66
     1
    
      
    
      
     10
     -63
     1
    
      
    
      
     11
     -60
     1
    
      
    
      
     12
     -57
     1
    
      
    
      
     13
     -54
     1
    
      
    
      
     14
     -51
     1
    
      
    
      
     15
     -48
     1
    
      
    
      
     16
     -45
     1
    
      
    
      
     17
     -42
     1
    
      
    
      
     18
     -39
     1
    
      
    
      
     19
     -36
     1
    
      
    
      
     20
     -33
     1
    
      
    
      
     21
     -30
     1
    
      
    
      
     22
     -27
     1
    
      
    
      
     23
     -24
     1
    
      
    
      
     24
     -21
     1
    
      
    
      
     25
     -18
     1
    
      
    
      
     26
     -15
     1
    
      
    
      
     27
     -12
     1
    
      
    
      
     28
     -9
     1
    
      
    
      
     29
     -6
     0.99
    
      
    
      
     30
     -3
     0.85
    
      
    
      
     31
     0
     0.71
    
      
    
      
     32
     3
     0.6
    
      
    
      
     33
     6
     0.51
    
      
         
  
      
 
      
 
      Note that at an input of -6dB (the threshold), the output = input (well, it's 0.99, but close enough).
      
 
      At 0dB, the output is 0.707, or -3dB.
      
 
      At 6 dB, the output is 0.51, or -6dB.
      
 
      You can make your own curves and calculate the parameters in manually if you prefer.
      
 
      In the GUI, the maximum ratio achievable is limited. However, you can enter in your own parameter data (or right click on a blue point and choose "Set Point Value" to bypass this limitation.
      
 
      You are correct, the x values are always in 3 dB spacings.
      
 
      The new "Standard RMS Compressor" has now been released - Check the toolbox under Dynamics Processors > RMS > Standard Resolution > Lower Range.
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

      • 


    


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