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SPORT synchronisation



		

			

									
					    ChristianH
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Nov 29, 2016 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    
 
    I was searching through the discussions here but there was not the answer I was looking for.
    
 
    I'm using the ADSP-21489 in my design which is sending and receiving data on all SPORTs (A and B).
    
 
    Each SPORT channel is running with DMA chaining to/from PING/PONG buffers.
    
 
    The data format is 32Bit I2S with 2 or 8 channels with 96kHz samplerate, all clocks are supplied external from an FPGA.
    
 
    Obviously the data change of the 8-channel I2S lines occurs earlier than on 2-channel I2S.
    
 
    Also the interrupts from transmitters are coming earlier (relative to L/R clock) than receivers.
    
 
    I need to trigger an audio processing interrupt every sample where I copy the data to/from PING/PONG buffers for further processing. At the moment I'm using the interrupt from the lowest priority 2-channel receiver SPORT DMA channel for starting processing. E.g. SP0=RX2, SP1=RX2, SP2=RX8, SP3=TX8, SP4=TX2, SP5=RX8, SP6=TX8 -> using SP0 IRQ.
    
 
    Is there a "good practice" guideline or application note for such a configuration?
    
 
    Any recommendations on which SPORT channel should be used for what data (priority levels!!), which SPORT interrupt to use for synchronisation, etc..? Shoud I put 8-channel lines to higher priority SPORTs than 2-channel lines?
    
 
    How to start such a configuration safely in sync?
    
 
    Regards
    
 
    Christian
    
								
    

				
				
		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    


	
    
		
	
    















    
	
    
	
    
					



			








	
	
	
	



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													0
							
			
				
									
							        
			
			
			
        
            
			                            
                        
                on Dec 12, 2016 6:43 AM
            
            
					
        
	
        

		
		
        
					
        Hello Jithul,
        
 
        of course the 8-channel I2S is multichannel mode with a 1 BCLK delay of the data (so I2S like).
        
 
        With synchronisation I mean which SPORT DMA interrupt to use best to start audio processing on the data i.e. which DMA IRQ is the "latest" of them so that all data words from the preceeding sample have been stored or received by all SPORT DMAs. I saw TX IRQs come earlier than RX, 8-channel of course also (because 8-channel BCLK is faster than 2-channel).
        
 
        Also regarding start of the SPORT interfaces and DMAs I saw that when waiting for the inactive LRCLK level as proposed and I start the SPORTs in that phase the TX DMAs already start working while RX DMAs are starting with the active LRCLK...
        
 
        Regards
        
 
        Christian
        
			
        

		
		
		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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													0
							
			
				
									
							        
			
			
			
          
            
			                            
                        
                on Dec 12, 2016 6:43 AM
            
            
					
          
	
          

		
		
          
					
          Hello Jithul,
          
 
          of course the 8-channel I2S is multichannel mode with a 1 BCLK delay of the data (so I2S like).
          
 
          With synchronisation I mean which SPORT DMA interrupt to use best to start audio processing on the data i.e. which DMA IRQ is the "latest" of them so that all data words from the preceeding sample have been stored or received by all SPORT DMAs. I saw TX IRQs come earlier than RX, 8-channel of course also (because 8-channel BCLK is faster than 2-channel).
          
 
          Also regarding start of the SPORT interfaces and DMAs I saw that when waiting for the inactive LRCLK level as proposed and I start the SPORTs in that phase the TX DMAs already start working while RX DMAs are starting with the active LRCLK...
          
 
          Regards
          
 
          Christian
          
			
          

		
		
		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

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