9 Replies Latest reply on May 19, 2011 8:41 AM by vishnu.kumar

    Delta_sigma_

    vishnu.kumar
        • 1. Re: Delta_sigma_
          vishnu.kumar

          Hi i am trying to interface loadcell to PSoC1. for this i am using Delta_sigma_ADC it is continuosly showing "0v" only what might be the problem?  here i am attaching my project.

             

           

             

          Thanks & Regards

             

          V.Vishnu Kumar

          • 2. Re: Delta_sigma_
            graa

            Check out the below blog article.  Check if your project has any of the mistakes outlined in the article.

               

             

               

            PSoC1 ADCs - The Five Golden Rules

               

             

               

            Best Regards,

               

            Ganesh

               

            The PSoC Hacker

            • 3. Re: Delta_sigma_
              vishnu.kumar

              Hi

                 

              yaa i've studied that article this before and i've done ADC application uisng ADCINC. but in the place of ADCINC if i am using Delta-Sigma-ADC i am not getting any variation in the reading it is continuously showing "0V" only

                 

               

                 

              thanks & regards

                 

              V.Vishnu Kumar

              • 4. Re: Delta_sigma_
                content.librarian

                I have looked at your project  and I have some questions

                   

                 

                   

                 

                   

                What is your in put  you have the ADC set for single ended and it is connected to two pins.  You also have some PGAs with a gain of foue.  If use are not using the PGA for the test, remove them they just confuse things.

                   

                Tr this experiment.  Take the column zero compaprtor LUT and set it to true.  Then run the ADC .  You shouls get full scale.  If you do there is someting wrong with the analog.  If you still get zero ther is something wrong with the Software.  Try that and let me know what you find.

                   

                 

                   

                Dave

                • 5. Re: Delta_sigma_
                  vishnu.kumar

                  hi 

                     

                  i am using PGA to amplify the loadcell signal.(after getting the result i will connect ADC through PGA).

                     

                  and coming to analo comparator 0 i've made it as TRUE. but still the problerm is same. i am unable to fix the problem......

                     

                  and here i am attaching one doucument which is explaing about loadcell and psoc interface.

                     

                   

                     

                  Thanks & Regards

                     

                  V. Vishnu Kumar

                  • 6. Re: Delta_sigma_
                    graa

                    What voltage are you applying to P2[1]?  Are you connecting the loadcell directly to P2[1]?  If yes, then the loadcell voltage may be too small to be measured by the ADC directly.

                       

                     

                       

                    Best Regards,

                       

                    Ganesh

                    • 7. Re: Delta_sigma_
                      vishnu.kumar

                      Hi

                         

                      i've now removed delta sigma adc and kept "ADCINCVR" ,"INSAMP"  & "PGA". Now i am getting adc values but voltage variation across load cell is very small if the weight is increasing in kgs only i am able to see variation in adc. i would like to get vartion for even if weight changed (100grams) like that . how we can do this? and why delta sigma adc is not working ? it is always showing 0v only. here i am attaching new project with all modifications.

                         

                       

                         

                       

                         

                      thanks and regards

                         

                      Vishnu

                      • 8. Re: Delta_sigma_
                        graa

                        I dont understand what you are doing with the INSAMP in the project. 

                           

                         

                           

                        Regarding very small ADC variation only when you apply weight in kilograms to the ADC, you will have to amplify the loadcell output to match the ADC's input range.  As you have selected the reference as Vdd/2 +/- Vdd/2, the ADC has a range of Vcc, ie, if you Vcc is 5V, the ADC range is 5V.  Find out what is the full scale output of the load cell and amplify this to match the range of the ADC.

                           

                         

                           

                        For example, if you loadcell produces 100mV for a fullscale weight then you should amplify this signal by 50.  When you do this, you will then get ADC variations for smaller weights too.  So, set the gain of the PGA according to the load cell output and check.

                           

                         

                           

                        Best Regards,

                           

                        Ganesh

                        • 9. Re: Delta_sigma_
                          vishnu.kumar

                          hi ganesh sir thanks for the reply.

                             

                          here i am using 4 load cells which are connected as wheatstone bridge arrangement. here i am using INSAMP in order to obtain single eneded voltage. this before i've included one pdf named loadcell. In that i've seen some methods. one method is explaing about INSAMP and ADC.  again here i am attaching the file please see that once. and on more thing how i can adjust the fullscale of ADC to predifined value (i am unable understand which is mentioned in datasheet). please kindly explain about that. 

                             

                           

                             

                          Thanks and regards

                             

                          Vishnu