Capsense guidance

Projects General Guidance
1

Hey guys

I am working on a "capacitive distance sensor".
So far the work on my project is going well

The only problem I have is that the return values from the Arduino
are fluctuating perfectly (meaning every few values) from low to high values (from about 40 to 100)
The following is my code, and the graph is attach'd.

The higher the value, the closer my hand is.
Note the 'grass' when nothing is around the aluminum foil (lowest point).

The foil is about 3cm x 3cm;
grounding cap is 100pF (101);
using a 15M resistor;

My plan is to output the values through the PWM port, scaling is easy
but I just need stable values.

Any suggestions?

Thanks;

#include <CapSense.h>

CapSense   cs_4_2 = CapSense(4,2);        // 10 megohm resistor between pins 4 & 2, pin 2 is sensor pin, add wire, foil
CapSense   cs_4_5 = CapSense(4,5);        // 10 megohm resistor between pins 4 & 6, pin 6 is sensor pin, add wire, foil
CapSense   cs_4_8 = CapSense(4,8);        // 10 megohm resistor between pins 4 & 8, pin 8 is sensor pin, add wire, foil

long rx1=0;
byte rx2=0;
String rxc1=0;
String rxc2=0;

String final=0;

void setup()                    
{
   cs_4_2.set_CS_AutocaL_Millis(0xFFFFFFFF);     // turn off autocalibrate on channel 1 - just as an example
   Serial.begin(9600);
}

void loop()
{
    long start = millis();
    rx1 =  cs_4_2.capSense(10);                  //R channel
    rx1/=2;
    Serial.println(rx1);

    delay(10);
}

Image, taken from Processing.

2

Not sure if this makes sense to your specific need, but you can try one of these:
(1) Reduce the Resistance (~1M or 500k) so that the sensitivity range of output becomes lower. This way, your values will be quiet stable and the precision is lowered.
(2) Increase the delay time in the code. You can try something ~100 or 50 depending on your need.
Good luck.