1 2 Previous Next 20 Replies Latest reply on Jan 16, 2015 10:20 AM by user_14586677

    Questions about capacitive sensor approach

    wei.tan

                Hello everyone,

         

      i am new in the community and currently working on building a demonstrator for our conductive film. I have some problems which i can't figure out myself. Hope someone can give me some advice.

         

      I plan to separate the conductive film into 10 isolated sliders. When we touch any of the slider, there will be visual indication of touched slider with LCD and LEDs, meanwhile, there will be sound effect too.

         

      I  ordered the CY8CKIT-050B Kit, which contains CapSense CSD component with two Bottons and five Linear Sliders.
      Normally if we use the sensor buttons or sliders on the kit, we need to add a CapSense_CSD component to the hardware design schematic file (TopDesign.cysch). After that we can configure the sliders or buttons and assign the slider segments to corresponding IO Pins.

         

      In my opinion, there are two approaches:

         

      1) I connect  my conductive sliders to the sensor button and sliders on the kit with wires. But the problem is: there are only 2 buttons and 5 sliders, which are not enough for 10 conductive strips.

         

      2) I connect my conductive sliders directly to the GPIOs and use them as external sensor compenents. But will that work? How can i realize it in my Topdesign schematic? Can I also somehoe use CapSense_CSD?

         

      Thanks for your help!

         

      Sammi

        • 1. Re: Questions about capacitive sensor approach
          user_1377889

          Welcome in the forum!

             

          The Kit-050 has got 2 buttons and one slider with 5 elements. You may add additional sliders with some elements and connect them to some free pins of the PSoC5. Then modify the properties of the CSD component accordingly.

             

          There is an expansion board which can be used with the Kit-050, look here secure.cypress.com/

             

           

             

          Bob

          • 2. Re: Questions about capacitive sensor approach
            wei.tan

            Hello Bob,

               

            thanks for your advice!

               

            I thought of using CY3280-SLM as an expansion board. But i consider this as a plan B. I would like to build thie prototype without an expansion board in order to save some area.

               

            You told me i can add additional sliders and then connect them to the free pins. I don't really understand that.

               

            I knew that in the Topdesign file i can configure the component CapSense_CSD and I can add linear sliders or Buttons in the Widgets config.

               

            However, the problem is: how can i assoicate the added sliders with physical sliders. There is indeed only 5 physical sliders on the kit.

               

            Sammi

            • 3. Re: Questions about capacitive sensor approach
              user_1377889

              Let us agree about the vocabulary first:

                 

              Your Kit-050 doed not have 5 sliders, it has got one (1) slider made out of 5 segments.

                 

              If you want another (one more) slider you have to make a (small) pcb that has the correct traces for the segments and a wired connection to your Kit.

                 

              Have a look into the schematics of your PSoC5 board to see how the connections of the sensor traces is made.

                 

               

                 

              Bob

                 

               

                 

              PS Where in Germany are you located? I live near Bremen

              • 4. Re: Questions about capacitive sensor approach
                wei.tan

                Hallo Bob,

                   

                 

                   

                danke für deine Hilfe! Ich wohne in Stuttgart.

                   

                 

                   

                Viele Grüße

                   

                Wei

                • 5. Re: Questions about capacitive sensor approach
                  user_1377889

                  Wei,

                     

                  Stuttgart is not so far away from Nuremberg (Nürnberg) where you can meet Cypress at the "embedded world" end of February. I always found it very informative and there are usually some engineers like Mark Saunders who are willing to answer any question.

                     

                   

                     

                  Bob

                  • 6. Re: Questions about capacitive sensor approach
                    wei.tan

                    Hello Bob,

                       

                     

                       

                    thanks for your information. You are right with the vocabulary.

                       

                    You said that:  If you want another (one more) slider you have to make a (small) pcb that has the correct traces for the segments and a wired connection to your Kit.

                       

                    I want to connect my own touch elements (which is conductive nanomaterial coated on PET substrate, and structrured into different segments) to the board. Since the Capsense IC is integrated in the main CPU, i think i just need to make a wired connection from my touch segments to the GPIOs. For example, In the attached schematic, the Capsense Buttons and Slider are routed to the P5[0] to P5[6].

                       

                    But somehow i don't believe it can be so easy because of the signal routing and stuff.  What do you think?

                       

                    Regards

                       

                    Wei

                    • 7. Re: Questions about capacitive sensor approach
                      user_1377889

                      Wei,

                         

                      hopefully you are not dissappointed, but it is that easy. Start with a self-made button before you make a slider, could be easier.

                         

                      You can find a bunch of docs to read about CapSense here www.cypress.com/capsense/ I recommend for your case the "Design Guidelines"

                         

                       

                         

                      Bob

                      • 8. Re: Questions about capacitive sensor approach
                        wei.tan

                        Hello Bob,

                           

                         

                           

                        thanks ! I think i just need to try out! Btw, i don't see any buzzer on the PSoC kit. Is it possible to make any sound effect with the board?

                           

                         

                           

                        Best regards

                           

                        We

                        • 9. Re: Questions about capacitive sensor approach
                          user_1377889

                          You may use a PWM to generate an output pulse-stream form on a pin, the drive mode is a bit limited and when connecting a coil you should take precautions that no overshoots are generated which could stress the pin above "Absolute Maximum Ratings" as listed in the PSoC5 Family Datasheet. The integrated protection diode can only swallow 100µA.

                             

                           

                             

                          Bob

                          • 10. Re: Questions about capacitive sensor approach
                            wei.tan

                            Hello Bob,

                               

                             

                               

                            but i need to install a speaker for audio output. Or is it integrated?

                               

                             

                               

                            sammi

                            • 11. Re: Questions about capacitive sensor approach
                              user_1377889

                              Your PSoC5 Kit hasn't got a speaker on board. Here is a recent discusion on how to connect a speaker for audio (speach, music) to a PSoC www.cypress.com/. In case of simple "Beeps" the connection should be made with digital outputs.

                                 

                               

                                 

                              Bob

                              • 12. Re: Questions about capacitive sensor approach
                                user_14586677

                                If you are going to use a voice coil speaker be sure to

                                   

                                use protection diodes to clamp any transients that exceed

                                   

                                 Vtrans > Vdd or Vtrans < Vss. Otherwise you potentially will

                                   

                                destroy PSOC. A series R with speaker and protection diodes

                                   

                                on speaker side of R best plan. R ~= 200+ ohms. Vout connected

                                   

                                to speaker to ground. This of course is digital, not voice grade

                                   

                                interface.

                                   

                                 

                                   

                                   

                                 

                                   

                                If using ceramic speaker take a look at attached.

                                   

                                 

                                   

                                Regards, Dana.

                                • 13. Re: Questions about capacitive sensor approach
                                  wei.tan

                                  Hello Dana,

                                     

                                   

                                     

                                  can i also drive the speaker like below (you posted this schematic in another discuss)? The diodes can  clamp any transients that exceed Vtrans > Vdd or Vtrans < Vss.  But the design below is for 2 speakers, why is that?

                                     

                                  The speaker needs to be driven by an op-amp,  but what is the difference between using an integrated Opamp and programmable gain amplifier?

                                     

                                  Regards

                                     

                                  Sammi

                                     

                                   

                                     

                                   

                                  • 14. Re: Questions about capacitive sensor approach
                                    user_1377889

                                    Wei, when you follow that thread a bit further you'll see that there is not a big difference. The idea behind was to increase the power for the speaker by driving the audio signal to Vdd and Vss. With only one amplifier you may reference the signal to Vdd/2,

                                       

                                    The name for this is "Push-pull amplifier", in German "Gegentakt EndStufe"

                                       

                                     

                                       

                                    Bob

                                    1 2 Previous Next