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DCC1 error signal

Vaclav Cechticky
Intellectual 560 points

Other Parts Discussed in Thread: HALCOGEN

Hello,

I'm using in my application the module DCC1, where Clock Source 0 is HF_LPO and Clock Source 1 is PLL1. I made the complete configuration in HalCoGen and then generated code. Additionally, I mapped the DCC1 error signal to the Error Signaling Module's group1 channel 30. 

I can easily provoke the DCC1 error signal when I change the Count 0 or Count 1 to an invalid value. However, I receive the DCC1 error signal even if the Count 0 and Count 1 are correct and all other settings seem to be fine as well. In this case, the DCC1 error signal arises sporadically, it takes a few seconds or sometimes even a few minutes. In fact, when I touch the oscillator on my eval board (RM48 HDK), then it arises almost immediately. It seems that the oscillator provided on the eval board is rather sensitive to external disturbances, or the HF_LPO is not providing the correct signal. What else can the matter be? Did you observe the same effect? 

Thank you

Regards

 Vaclav

  • 0
    Intellectual 560 points

    Hello,

    I'd like just to add that I'd be very interested for a compensation guide document for the internal oscillator containing:

    - desciption of a method compensating internal oscillator
    - what is the frequency drift caused by temperature, in what temperature range ...
    - ...
    

    Can you point / provide me such a document for RM48 or TMS570?
    

    Thank you
    

    Vaclav
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Vaclav Cechticky
					
									
    
	
    
	                                    
                      
    
                        
                          TI__Expert
                        7650 points
                      
    
                          
                   		
		
    
					
    Hi Vaclav,
    

    We received your post and are checking with our experts to see what we can share.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Brian Fortman
					
									
    
	
    
	                                    
                      
    
                        
                          TI__Expert
                        7650 points
                      
    
                          
                   		
		
    
					
    Vaclav,
    

    An update, for the main oscillator (XTAL connected) there is no frequency drift within the microcontroller although the crystal does drift and that should be a function of the crystal spec.
    

    The on chip low power OSC, or LPO, is meant to be used in a limp mode operation in the case where there is a fault/safety issue with the external XTAL to allow the MCU to execute a safe shutdown.  This OSC will drift with temp and it is not specified since the functional situation doesn't call for it and this was not a critical feature for the design.
    

    

    Are you not finding the the data you need in the TRM? www.ti.com\lit\SPNU503 The PLL and oscillator chapter describes how the oscillators are built and respond.
    

    

    We are trying to recreate the DCC error on one of our HDKs.  Will post again when we have an update.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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