Thread Details

  • State Verified Answer
  • Replies 2 replies
  • Subscribers 31 subscribers
  • Views 489 views
  • Users 0 members are here
Options
Related 

        

            Post
             Go back to editing
        

    

    


    

    









		


















	
	
			
	
			
		
	
	
		

	    
	    
	    		
Different Resistance Values for AD5293

		
	
				

			

									
					    TotyAsdfghjk
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Feb 19, 2025 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user is experiencing erratic resistance values when cycling through bit settings on an AD5293 digital potentiometer. The final answer suggests disabling the default write protection on the RDAC register by setting bit C1 to 1. However, the user reported that this did not resolve the issue, and the resistance values still show unexpected jumps, suggesting a possible bit offset problem.
                        	    
    
                
                     AI Generated Content
                
    	    
    
             
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Hardware
    
    		        		            		    
    Product Number:  AD5293  
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hello, I have the following problem:
    

    I am testing two AD5293 digital potentiometers, and when cycling through all bit values to set the resistance, one of them behaves strangely. At some points, it shows out-of-range values, such as 180kΩ (which I assume is an open circuit). Then, it starts working normally, varying between approximately 50kΩ and 100Ω.
    

    However, when I try to set values manually, the readings are inconsistent. For example, at a setting of 0, it measures 166Ω; at 512, it measures 30kΩ; and at 1023, it measures 220Ω.
    

    Meanwhile, the other potentiometer, which behaves more consistently, gives these values at 0, it measures 37.3kΩ; At 512, it measures 20.5kΩ; At 1023, it measures 180Ω.
    

    Does anyone know what might be causing this? Is there a way to calibrate it, or could the potentiometer be damaged?
    

    This is the code i'm using:|
    

    

    

    #include <SPI.h>
    

    

    const int slaveSelectPin = 5;  // CS
    

    const int CLK = 18;
    

    const int SDO = 19;
    

    const int DIN = 23;
    


    

    void setup()
    

    {
    

      pinMode(slaveSelectPin, OUTPUT);
    

      SPI.begin();
    

      SPI.beginTransaction(SPISettings(1000000, MSBFIRST, SPI_MODE1));
    

      Serial.begin(115200);
    

    

      digitalWrite(slaveSelectPin, LOW);
    

      SPI.transfer(0x18);
    

      SPI.transfer(0x00); // Performance Mode
    

      digitalWrite(slaveSelectPin, HIGH);
    

      SPI.endTransaction();
    

    

      init_digiPot();
    

    }
    

    

    void loop()
    

    {
    

      /*
    

      digitalPotWrite(0);
    

      delay(4000);
    

      digitalPotWrite(512);
    

      delay(4000);
    

      digitalPotWrite(1023);
    

      delay(4000);
    

      */
    

      unsigned int val;
    

      for (val = 0; val <= 1023; val++) {
    

        digitalPotWrite(val);
    

        delay(100);
    

      }
    

      for (val = 1023; val > 0; val--) {
    

        digitalPotWrite(val);
    

        delay(100);
    

      }
    

    }
    

    

    void init_digiPot()
    

    {
    

      SPI.beginTransaction(SPISettings(1000000, MSBFIRST, SPI_MODE1));
    

      digitalWrite(slaveSelectPin, LOW);
    

      SPI.transfer(0x18); 
    

      SPI.transfer(0x02); // Wiper update
    

      digitalWrite(slaveSelectPin, HIGH);
    

      Serial.print("Setup: ");
    

      Serial.println();
    

      SPI.endTransaction();
    

    }
    

    

    void digitalPotWrite(unsigned int val) {
    

      SPI.beginTransaction(SPISettings(1000000, MSBFIRST, SPI_MODE1));
    

      digitalWrite(slaveSelectPin, LOW);
    

      byte highbyte = (val >> 8) + 0x04;  //high wiper byte + command wiper update
    

      byte lowbyte = val & 0xFF;
    

      SPI.transfer(highbyte);  //send wiper data high byte
    

      SPI.transfer(lowbyte);   //send wiper data low byte
    

    

      Serial.print("Val: ");
    

      Serial.println(val);
    

      digitalWrite(slaveSelectPin, HIGH);
    

      SPI.endTransaction();
    

    }
    

    

    

    

    
			
    
			
									
		                             
                        

    
    
                                            
                 D/A Converters (DAC)
                
                                                    
                 hardware
                
                                                    
                 ad5293
                
                                                    
                 data converters
                
                                                    
                 Digital Potentiometers (DigiPOT)