Teensy touchread values documentation

[ravikj]

I am able to read the result of touchread() function and reproduce the experiment using a copper strip
I have gone through the forums and ,and have understood that adding a resistor will increase sensitivity.

What units is the reading of capacitance ? Without touch the values for NO touch is the same. However the value for TOUCH is very very large. Below is an example

with a low resistance 500K

850
850
890 <----touch
900
850
850 < no touch

with 1M ohm resistor
850
850
1400 <----touch
1500 <--touch
850
850 < no touch



In this case what does the high values of 890 /1500 actually mean in terms of Farads ? Or is it just a relative reading, and the project has to calibrate (convert) it in terms of Farads.

 

[doughboy]

this does not exactly answer your question, but may be an option to what you are trying to do.

I posted this code in another thread.
It self calibrates the touch sensor and gives you the threshold value, and anything > than the threshold = touch.
The calibration is done at runtime, even if you change the environment on the fly at runtime, the code will detect and recalibrate.

you need to edit the code to use the touch pins you are using.