MPR121 interrupt request issue

Projects Programming
1

Hi all,

In the interest of your time, I'll keep this brief.

Equipment: Arduino Mega, MPR121 (Overview | Adafruit MPR121 12-Key Capacitive Touch Sensor Breakout Tutorial | Adafruit Learning System)

Code:

#include <Wire.h>
#include "Adafruit_MPR121.h"

Adafruit_MPR121 cap = Adafruit_MPR121 ();

volatile bool f0 = 0;
volatile bool f1 = 0;
volatile int touchStatus;


void ISR_touch () {
  f0 = 1;
  touchStatus = cap.touched ();
}

void setup () {
  pinMode (18, INPUT_PULLUP);
  attachInterrupt (digitalPinToInterrupt (18), ISR_touch, LOW);
  Serial.begin (9600);
  cap.begin (0x5A);


}

void loop () {
  if (f0 == 1) {
    f0 = 0;
    if (touchStatus == 1){
      Serial.println ("1 touched");
    } else if (touchStatus == 0) {
      Serial.println ("1 released");
    }
  }
}

Expected outcome:
When I touch the first electrode of the touch IC breakout, I'd get a serial message that that pin has been touched. When I release it, I'd get a serial message that that pin has been released.

Actual outcome:
Nothing happens when I touch electrode 1 of the touch IC breakout.

Thank you.

2

Sorry all, figured out the issue.

I need a level shifter. The "low" signal from the chip breakout is 2.3V—so under 3V. So, Arduino doesn't count that "low" as a true "low."