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PWM_OFS_AUTO = 255 (maximum value) after autotuning process

		
	
				

			

									
					    AdrienB
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jan 17, 2024 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  TMC2300 
    
    		        		    		    
    
		    		    
		    			
    
			    
    TMC2300 includes an automatic tuning process for the chopper. This automatic process sets PWM_OFS_AUTO and PWM_GRAD_AUTO.
    

    PWM_OFS_AUTO is tuned first, by maintaining the stepper in standstill with nominal current for at least 130ms. If I understood correctly, the goal is to adjust PWM_OFS_AUTO so that PWM_SCALE_AUTO = 0.
    

     
    

    At the end of the standstill tuning process of my system, PWM_OFS_AUTO = 255 (the maximum value) and PWM_SCALE_AUTO = 30. The test is run with IHOLD=20, which is the nominal current for my system.
    

     
    

    Is it problematic? Should the system be modified in some way (rsense?) to bring PWM_SCALE_AUTO to zero?
    
			
    
			
									
		                             
                        

    
    
                                            
                 hardware
                
                                                    
                 stepper motor
                
                                                    
                 TMC2300
                
                                
            
    
    
    
		
    

				
				        
        		
    
			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		
    

        
        
        
    
					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Aug 29, 2024 4:12 AM
            
            
						
			            		
      
		
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      Hi, the PWM_OFS_AUTO is calculated for a theoretical current setting of IRUN=31. With IRUN set to a lower value (20) to reach the motor's nominal current, therefore the value might saturate in combination with a high coil resistance and a low supply voltage. To optimize, you could go for a bit higher sense resistor value, so that in turn, a higher IRUN setting is applied. But, in my feeling the deviation is not large, so unless you experience insufficient torque at motor spin-up, no need to change. 
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
						
						
				
				
		
		
      
			
		
      
	
      

      

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