I would like to use the 'Native Capacitive Sensors without additional
Hardware' program with more than 6 pins, however I am not sure this is
possible? I am working with a mega arduino, has anyone done this
before? Here is the program -
Native Capacitive Sensors without additional Hardware
Sensor key demonstrates how the Arduino can sense a touch sensitive key through digital pins 8 to 13. It requires no special hardware, nevertheless a capacitor of 1nF is recommendet in line with the pin to decouple 50Hz noises.
Connect a wire or some metallic plate to a digital pin (digital 8-13).
The program measures the capacity (time to charge) of the given port. If untouched getcap returns a low value e.g. "1" when touched it rises to about 5. By adding som comparision with a threshhold you can make it a boolean key input.
DO NOT CONNECT ANY ACTIVE DRIVER TO THE USED PIN !
the pin is toggled to output mode to discharge the port capacity, which would shortcut any chip/transistor which might drive the port high.
Mario Becker, Fraunhofer IGD, 2007 http://www.igd.fhg.de/igd-a4
// sensor key
#define KEYPORT PORTB
#define KEYDDR DDRB
#define KEYPIN PINB
#define KEY0 PB0 // capture input - digital 8
#define KEY1 PB1 // capture input - digital 9
#define KEY2 PB2 // capture input - digital 10
#define KEY3 PB3 // capture input - digital 11
#define KEY4 PB4 // capture input - digital 12
#define KEY5 PB5 // capture input - digital 13
void setup()
{
Serial.begin(9600); // connect to the serial port
}
// returns capacity on one input pin
// pin must be the bitmask for the pin e.g. (1<<PB0)
char getcap(char pin)
{
char i = 0;
KEYDDR &= ~pin; // input
KEYPORT |= pin; // pullup on
for(i = 0; i < 16; i++)
if( (KEYPIN & pin) ) break;
KEYPORT &= ~pin; // low level
KEYDDR |= pin; // discharge
return i;
}
void loop ()
{
char capval[6];
char pinval[6] = {1<<KEY0,1<<KEY1,1<<KEY2,1<<KEY3,1<<KEY4,1<<KEY5};
delay(1000);
for(char i = 0; i < 6; i++)
{
capval = getcap(pinval*);*
* Serial.print("digital ");*
* Serial.print(i+8, DEC);*
* Serial.print(": ");*
_ Serial.println(capval*, DEC);
}
Serial.println("");
}*
Thanks_