Absolute Capacitance using CapSense (CSX)

[ShKh_2014656]

Hi All,

       

I have made a pressure sensor which is basically a capacitor. I just need to get the absolute capacitance (or raw count) value using CSD widget. I don't need any other feature for now, but just the absolute value. Can you guys help me use CSD widget to find capacitance of a capacitor?

   

I am using PROC module provided with BLE Pioneer Kit. I'll move to another module but I want to get familiar with CSD widget. As far as I understand I'll be using Mutual Capacitance (CSX), and it would be great if you could help me specifically with that.

   

I tried to go over code examples and documentation but they mostly talk about touch buttons, proximity sensing, etc. Your help will be much appreciated.

[ShKh_2014656]

If I short the terminals (the capacitor input terminals, I get this)

       

[ShKh_2014656]

So far I have done this. For now I'm using ceramic capacitors of different values to test the functionality. No matter which capacitor I attach, the output value remains the same. Need help.

       

I am hooking up the capacitor on Pioneer Kit P3.4 and P3.5

   

   

[rola_264706]

   

I would try this to measure a Cap.

   

[Anonymous]

I think it would be better to use self capacitance. At mutual capacitance you send a frequency on the transmitter (X) and receive charge on Y, but you need an electric field between X and Y. With descrete components this don't work. With self capacitance there is no coupling from X to Y, only X (or Y) and an electric field to infinity.

   

Also you should turn off all auto sense because it changes the absolute values (e.g. with gain) to get good differences. With cap sense you are measuring differences of fF, so if your C is to big it could not be loaded completely.