Human Body as connector

Using Arduino Project Guidance
#1

Hi everyone,

I have a pretty simple installation project: i would like to create sort of a keyboard (multiple PushButtons) of which each key, when its pressed, send a data to Processing to tell it to launch a sound or a video or both in the room.

For now, my code is a modified "StateChangeDetection" sketch, where every pin is dedicated to a key.

Also, i would like to use the human body to close the circuit and allow arduino to send data to processing: The naked feet on a metal board, the hand would slide on multiple conductive ink drawings. But here is the problem: in my circuit's actual state, the human body isn't equal at all to a classic pushbutton: the current don't seems to pass in my body.

Do you know why?

Pablo

#2

the human body isn’t equal at all to a classic pushbutton

Correct. The body has a much higher (and variable) resistance.

#3

Capacitive sensing may be an option.

#4

So do you know how to raise intensity enough (and safely) for the body to close the circuit?

groundFungus:
Capacitive sensing may be an option.

Thanks groundFungus, i'll take a close look to this library.

#5

, the human body isn't equal at all to a classic pushbutton: the current don't seems to pass in my body.

Do not use a pull down resistor use the pull up configuration. Then use an external pull up resistor of 1M, do not enable the internal ones.

If that doesn’t work try the same setup with an analogue pin and look at the reading with and without the body in the circuit.

#6

groundFungus:
Capacitive sensing may be an option.

I second that, but not using the Capsense library - I have not had much luck with that.

Use these modules:

#7

Okay i’ve mounted a circuit using the capsens library, but it’s not doing so well. It may be because of my code, or because of my circuit and the evident instability of the sensors which are interfering together.

Could somebody take a look to this code, and tell me how i could improve it ? By reducing its size using arrays for example (which i don’t know how to do)

#include <CapacitiveSensor.h>


      
CapacitiveSensor   cs_4_3 = CapacitiveSensor(4,3);        
CapacitiveSensor   cs_4_5 = CapacitiveSensor(4,5); 
CapacitiveSensor   cs_4_6 = CapacitiveSensor(4,6);        
CapacitiveSensor   cs_4_7 = CapacitiveSensor(4,7);        
CapacitiveSensor   cs_4_8 = CapacitiveSensor(4,8);
CapacitiveSensor   cs_4_9 = CapacitiveSensor(4,9);        
CapacitiveSensor   cs_4_10 = CapacitiveSensor(4,10);        
CapacitiveSensor   cs_4_11 = CapacitiveSensor(4,11);
CapacitiveSensor   cs_4_12 = CapacitiveSensor(4,12);        
CapacitiveSensor   cs_4_13 = CapacitiveSensor(4,13);        // 10 pins
     

void setup()                    
{
   cs_4_3.set_CS_AutocaL_Millis(0xFFFFFFFF);     // turn off autocalibrate on channel 1 - just as an example
   Serial.begin(9600);
}

void loop()                    
{
    long total3 =  cs_4_3.capacitiveSensor(30);
    long total5 =  cs_4_5.capacitiveSensor(30);
    long total6 =  cs_4_6.capacitiveSensor(30);
    long total7 =  cs_4_7.capacitiveSensor(30);
    long total8 =  cs_4_8.capacitiveSensor(30);
    long total9 =  cs_4_9.capacitiveSensor(30);
    long total10 =  cs_4_10.capacitiveSensor(30);
    long total11 =  cs_4_11.capacitiveSensor(30);
    long total12 =  cs_4_12.capacitiveSensor(30);
    long total13 =  cs_4_13.capacitiveSensor(30);
    

    if(total3 >50) {
    Serial.print(1);                  
}  
    if(total5 >50) {
    Serial.print(2);     
}           
  if(total6 >50) {
    Serial.print(3);     
}           
  if(total7 >50) {
    Serial.print(4);     
}           
  if(total8 >50) {
    Serial.print(5);     
}           
  if(total9 >50) {
    Serial.print(6);     
}           
  if(total10 >50) {
    Serial.print(7);     
}           
  if(total11 >50) {
    Serial.print(8);     
}           
  if(total12 >50) {
    Serial.print(9);     
}           
  if(total13 >50) {
    Serial.print(10);     
}           
    delay(10);                              
}

Paul__B:
I second that, but not using the Capsense library - I have not had much luck with that.

Use these modules:

This seems like a good solution also, but i would like my buttons to be quite large and extended, and not this small. But maybe starting from this little sensor i can make a large and unorthodox size button?

#8

Hillcres-Hellio:
This seems like a good solution also, but I would like my buttons to be quite large and extended, and not this small. But maybe starting from this little sensor I can make a large and unorthodox size button?

If you note the "thru" to the left of and below the "TOUCH" circle, it corresponds to the bottom right pad on the other side. You connect that - by as short a wire as possible - to your touch pad. The obvious thing is to mount this little board under each of your larger touch pads.

I understand that it calibrates itself to the size of the pad on switch-on, and thereafter detects touch or indeed, close proximity. The latter is for what I want them.

#9

my circuit and the evident instability of the sensors which are interfering together.

Yes they do, which is why I suggested that the capsense libiary would not be a good choice.

Nothing much you can do in code, it is down to your layout and the physical environment.

#10