Related Questions

Products Mentioned

AD5940 Recommended for New Designs
The AD5940 and AD5941 are high precision, low power analog front ends (AFEs) designed for portable applications that require high precision, electrochemical...
Datasheet
AD5940 on Analog.com

Associated Drivers

AD5941 Recommended for New Designs
The AD5940 and AD5941 are high precision, low power analog front ends (AFEs) designed for portable applications that require high precision, electrochemical...
Datasheet
AD5941 on Analog.com

  • State Verified Answer
  • Replies 6 replies
  • Subscribers 76 subscribers
  • Views 193 views - 176 Verified Views
  • Users 0 members are here
Options
Related 

        

            Post
             Go back to editing
        

    

    


    

    









		












	
	
			
	
			
		
	
	
		

		
Square Wave



		

			

									
					    Truong
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Oct 18, 2024 
				
			
			
		
    

				
		
    
		    		    
		    
		    		      		            		        
    Category: Software
    
    		        		            		    
    Product Number:  AD5941  
    
    		        		        		        
    Software Version:  @version: $Revision: 766 $
    
    		    		    	
			
    Dear Sir/Madam,
    

    I've been comparing AD5940 Square Wave Voltammetry measurement results to other commercial potentiostats and am not receiving the same results. I would like to clarify these questions I have:
    

    When I use oscilloscope to detect the output signal between WE (work electrode) and RE (Reference electrode). I have attached the signal and configure square wave signal. No matter how the RampeakVolt value changes, the start and end point of the signal at the inverse of RamStartVolt. I want to signal output look like the 3rd picture. (I couldn't take pictures of the waves so I drew a description).
    

    Hope to hear from you soon. 
    

    Best regards.
    

     
    

     
    

     
    

     
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 software
                
                                                    
                 ad5941
                
                                                    
                 Sensors and MEMS
                
                                                    
                 @version: $Revision: 766 $
                
                                                    
                 Electrochemical Sensors
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			


				
	









	
      
	

    • 
	
      



	
			
		
	



      
	
      
		
      
							
					
      
		
      
			
													+1
							
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Oct 20, 2024 9:10 PM
            
            
					
      
	
      

		
		
      
					
      Hi  ,
      

      Can your team please help look into this?
      

      Thanks,
      Janine
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
						
				
				
		
		
      
			
		
      
	
      

      

      • 

	

    • 
	
      



	
		
	
	



      
	
      
		
      
							
					
      
		
      
			
													0
							
			
				
									
							        
			
			
			
      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Oct 21, 2024 2:41 AM
            
            
					
      
	
      

		
		
      
					
      HI,
      

         Your SqrWvAmplitude is 200mV. Hence each jump is of 200mV amplitude.
      

      Could you check with a smaller SqrWvAmplitude?
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
						
				
						
				
				
		
		
      
			
		
      
	
      

      

      • 

	

    • 
	
      



	
		
	
	



      
	
      
		
      
							
					
      
		
      
			
													0
							
			
				
									
							        
			
			
			
        
            
						
                            
            
            				
            
                on Oct 22, 2024 5:06 AM
            
            
												
						in reply to Akila
					
									
        
	
        

		
		
        
					
        

        

        I don't understand why the VzeroStart and VzeroPeak values are needed. I read about Square Wave in AN-1563, I see there is no content talking about VzeroStar and VzeroPeak.
        Looking forward to an explanation of those two values in the code and what effect they have on the stat and end points of the signal.
        

        

        /**
        

        * @brief Calculate DAC code step by step. 
        

        * @details The calculation is based on following variables.
        

        *          - RampStartVolt
        

        *          - RampPeakVolt
        

        *          - VzeroStart
        

        *          - VzeroPeak
        

        *          - StepNumber
        

        *          Below variables must be initialzed before call this function. It's done in function @ref AppSWVInit
        

        *          - RampState
        

        *          - CurrStepPos
        

        *          - bDACCodeInc
        

        *          - CurrRampCode
        

        * @return return error code.
        

        */
        

        static AD5940Err RampDacRegUpdate(uint32_t *pDACData)
        

        {
        

          uint32_t VbiasCode, VzeroCode;
        

          
        

          if (AppSWVCfg.bRampOneDir)
        

          { 
        

          if(AppSWVCfg.RampStartVolt > AppSWVCfg.RampPeakVolt)
        

            AppSWVCfg.bDACCodeInc = bFALSE;
        

            switch(AppSWVCfg.RampState)
        

            {
        

            case SWV_STATE0: /* Begin of Ramp  */
        

              AppSWVCfg.CurrVzeroCode = (uint32_t)((AppSWVCfg.VzeroStart - 200.0f)/DAC6BITVOLT_1LSB);
        

              AppSWVCfg.RampState = SWV_STATE1;
        

              break;
        

            case SWV_STATE1:
        

              if(AppSWVCfg.CurrStepPos >= AppSWVCfg.StepNumber/2)
        

              {
        

                AppSWVCfg.RampState = SWV_STATE2;   /* Enter State2 */
        

                AppSWVCfg.CurrVzeroCode = (uint32_t)((AppSWVCfg.VzeroPeak - 200.0f)/DAC6BITVOLT_1LSB);
        

              }
        

              break;
        

            case SWV_STATE2:
        

              if(AppSWVCfg.CurrStepPos >= AppSWVCfg.StepNumber)
        

                AppSWVCfg.RampState = SWV_STOP;     /* Enter Stop */
        

              break;
        

            case SWV_STOP:
        

              break;
        

            }
        

          }
        

          
        

          else
        

          {
        

            switch(AppSWVCfg.RampState)
        

            {
        

            case SWV_STATE0: /* Begin of Ramp  */
        

              AppSWVCfg.CurrVzeroCode = (uint32_t)((AppSWVCfg.VzeroStart - 200.0f)/DAC6BITVOLT_1LSB);
        

              AppSWVCfg.RampState = SWV_STATE1;
        

              break;
        

              
        

            case SWV_STATE1:
        

              if(AppSWVCfg.CurrStepPos >= AppSWVCfg.StepNumber/4)
        

              {
        

                AppSWVCfg.RampState = SWV_STATE2;   /* Enter State2 */
        

                AppSWVCfg.CurrVzeroCode = (uint32_t)((AppSWVCfg.VzeroPeak - 200.0f)/DAC6BITVOLT_1LSB);
        

              }
        

              break;
        

              
        

            case SWV_STATE2:
        

              if(AppSWVCfg.CurrStepPos >= (AppSWVCfg.StepNumber*2)/4)
        

              {
        

                AppSWVCfg.RampState = SWV_STATE3;   /* Enter State2 */
        

                AppSWVCfg.bDACCodeInc = AppSWVCfg.bDACCodeInc ? bFALSE : bTRUE;
        

              }
        

              break;
        

            case SWV_STATE3:
        

              if(AppSWVCfg.CurrStepPos >= (AppSWVCfg.StepNumber*3)/4)
        

              {
        

                AppSWVCfg.RampState = SWV_STATE4;   /* Enter State2 */
        

                AppSWVCfg.CurrVzeroCode = (uint32_t)((AppSWVCfg.VzeroPeak - 200.0f)/DAC6BITVOLT_1LSB);
        

              }
        

              break;    
        

            case SWV_STATE4:
        

              if(AppSWVCfg.CurrStepPos >= (AppSWVCfg.StepNumber))
        

                AppSWVCfg.RampState = SWV_STOP;     /* Enter Stop */
        

              break;
        

            case SWV_STOP:
        

              break;
        

            }
        

            
        

          }
        

         
        

        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

        • 

	

      • 
	
        



	
		
	
	



        
	
        
		
        
							
					
        
		
        
			
													0
							
			
				
									
							        
			
			
			
        •  Analog Employees  
        
            
						
                            
            
            				
            
                on Oct 22, 2024 5:56 AM
            
            
												
						in reply to Truong
					
									
        
	
        

		
		
        
					
        SWV start voltage = RampStartVolt + VzeroStart
        

        SWV end volatge = RampPeakVolt + VzeroPeak
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

        • 

	

      • 
	
        



	
		
	
	



        
	
        
		
        
							
					
        
		
        
			
													0
							
			
				
									
							        
			
			
			
          
            
						
                            
            
            				
            
                on Oct 23, 2024 3:56 AM
            
            
												
						in reply to Akila
					
									
          
	
          

		
		
          
					
          For getting positive ramp, you config :
          

          

          pRampCfg->bRampOneDir = bTRUE;//bTRUE;
          

          But the results are not as expected, how do I configure the parameters of the square wave?
          Hope to hearing from you soon. 
          

          

          

          

          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
						
				
						
				
				
		
		
          
			
		
          
	
          

          

          • 

	

        • 
	
          



	
			
		
	



          
	
          
		
          
							
					
          
		
          
			
													+1
							
			
				
									
							        
			
			
			
          •  Analog Employees  
          
            
						
                            
            
            				
            
                on Oct 24, 2024 2:37 AM
            
            
												
						in reply to Truong
					
									
          
	
          

		
		
          
					
          Square wave parameters are configured here:
          

           
          

          You may capture the square wave by monitoring (VCE0 - VSE0) voltage using oscilloscope to check if excitation is as expected.
          
			
          

		
			
	      

		
		
	
          
	
          
		
          
			
		
          
	
          
	
          
		
						
				
						
						
				
				
		
		
          
			
		
          
	
          

          

          •