Can anyone help me with a small bug for this Touch Sensor please?

Projects Programming
1

Hello. Im trying to use an MPR121 to switch on a Relay, then switch it off either after 10 seconds or if the sensor is touched again. I have taken the majority of the code from this chap http://bildr.org/2011/05/mpr121_arduino/ . I'm not going to pretend I understand it all, so I have left a lot of it intact (I know i dont need the for loop when im only using one channel).

#include "mpr121.h"
#include <Wire.h>

long OnTime = 10000;
unsigned long CurrentTime = 0;
long PreviousTime = 0;
int RelayState = LOW;
int Relay = 13;
int irqpin = 2;  // Digital 2
boolean touchStates[12]; //to keep track of the previous touch states

void setup(){
  pinMode(irqpin, INPUT);
  pinMode(Relay, OUTPUT);
  digitalWrite(irqpin, HIGH); //enable pullup resistor
  
  Serial.begin(9600);
  Wire.begin();

  mpr121_setup();
}

void loop(){
  readTouchInputs();
}


void readTouchInputs(){
  if(!checkInterrupt()){
    
    //read the touch state from the MPR121
    Wire.requestFrom(0x5A,2); 
    
    byte LSB = Wire.read();
    byte MSB = Wire.read();
    
    uint16_t touched = ((MSB << 8) | LSB); //16bits that make up the touch states

    
    for (int i=0; i < 12; i++){  // Check what electrodes were pressed
      if(touched & (1<<i)){
           
        if(touchStates[i] == 0){
          //pin i was just touched
          Serial.print("pin ");
          Serial.print(i);
          Serial.println(" was just touched");
          if (RelayState == HIGH){
            RelayState = LOW;}
          else{
            RelayState = HIGH;}
                     
          digitalWrite (Relay, RelayState);
          PreviousTime = millis();
          delay(500);
        }
        
        else if(touchStates[i] == 1){
          //pin i is still being touched
        }  
        touchStates[i] = 1;   
        
      }else{
        if(touchStates[i] == 1){
          Serial.print("pin ");
          Serial.print(i);
          Serial.println(" is no longer being touched");
          
          //pin i is no longer being touched
       }
        
        touchStates[i] = 0;
      } 
    } 
}
  CurrentTime = millis();
    if (CurrentTime - PreviousTime > OnTime){
      PreviousTime == CurrentTime;
      digitalWrite (Relay, LOW); }

}




void mpr121_setup(void){

  set_register(0x5A, ELE_CFG, 0x00); 
  
  // Section A - Controls filtering when data is > baseline.
  set_register(0x5A, MHD_R, 0x01);
  set_register(0x5A, NHD_R, 0x01);
  set_register(0x5A, NCL_R, 0x00);
  set_register(0x5A, FDL_R, 0x00);

  // Section B - Controls filtering when data is < baseline.
  set_register(0x5A, MHD_F, 0x01);
  set_register(0x5A, NHD_F, 0x01);
  set_register(0x5A, NCL_F, 0xFF);
  set_register(0x5A, FDL_F, 0x02);
  
  // Section C - Sets touch and release thresholds for each electrode
  set_register(0x5A, ELE0_T, TOU_THRESH);
  set_register(0x5A, ELE0_R, REL_THRESH);
 
  set_register(0x5A, ELE1_T, TOU_THRESH);
  set_register(0x5A, ELE1_R, REL_THRESH);
  
  set_register(0x5A, ELE2_T, TOU_THRESH);
  set_register(0x5A, ELE2_R, REL_THRESH);
  
  set_register(0x5A, ELE3_T, TOU_THRESH);
  set_register(0x5A, ELE3_R, REL_THRESH);
  
  set_register(0x5A, ELE4_T, TOU_THRESH);
  set_register(0x5A, ELE4_R, REL_THRESH);
  
  set_register(0x5A, ELE5_T, TOU_THRESH);
  set_register(0x5A, ELE5_R, REL_THRESH);
  
  set_register(0x5A, ELE6_T, TOU_THRESH);
  set_register(0x5A, ELE6_R, REL_THRESH);
  
  set_register(0x5A, ELE7_T, TOU_THRESH);
  set_register(0x5A, ELE7_R, REL_THRESH);
  
  set_register(0x5A, ELE8_T, TOU_THRESH);
  set_register(0x5A, ELE8_R, REL_THRESH);
  
  set_register(0x5A, ELE9_T, TOU_THRESH);
  set_register(0x5A, ELE9_R, REL_THRESH);
  
  set_register(0x5A, ELE10_T, TOU_THRESH);
  set_register(0x5A, ELE10_R, REL_THRESH);
  
  set_register(0x5A, ELE11_T, TOU_THRESH);
  set_register(0x5A, ELE11_R, REL_THRESH);
  
  // Section D
  // Set the Filter Configuration
  // Set ESI2
  set_register(0x5A, FIL_CFG, 0x04);
  
  // Section E
  // Electrode Configuration
  // Set ELE_CFG to 0x00 to return to standby mode
  set_register(0x5A, ELE_CFG, 0x0C);  // Enables all 12 Electrodes
  
  
  // Section F
  // Enable Auto Config and auto Reconfig
  /*set_register(0x5A, ATO_CFG0, 0x0B);
  set_register(0x5A, ATO_CFGU, 0xC9);  // USL = (Vdd-0.7)/vdd*256 = 0xC9 @3.3V   set_register(0x5A, ATO_CFGL, 0x82);  // LSL = 0.65*USL = 0x82 @3.3V
  set_register(0x5A, ATO_CFGT, 0xB5);*/  // Target = 0.9*USL = 0xB5 @3.3V
  
  set_register(0x5A, ELE_CFG, 0x0C);
  
}


boolean checkInterrupt(void){
  return digitalRead(irqpin);
}


void set_register(int address, unsigned char r, unsigned char v){
    Wire.beginTransmission(address);
    Wire.write(r);
    Wire.write(v);
    Wire.endTransmission();
}

Its all working exactly as it should, except that after the timer has switched the Relay off, you have to press the sensor twice to switch it back on.
Im sure it just needs a line like

touchStates[i] = 0;

but if I add that after the relay is timed out, I get an error message about "undeclaired in this scope".
The sensor im using is on pin 1 but this doesnt work either:

touchStates[1] = 0;

Can anyone offer any guidance (Im sure its simple, Ive just been staring for too long) on how to reset that boolean value back to 0 before the code restarts in the 'timed out' path without affecting the 'switched' off' path?

Many thanks

2

I get an error message about "undeclaired in this scope".

What is "undeclared in this scope"?

but this doesnt work either:

Which channel are you using? The first is numbered 0, not 1.

3

I was experimenting weeks ago with the MPR121 for something like what you want to do, use a capacitive button to turn on and if touched again turn off something (you could attach a relay), here is the code if you have some questions, ask.

#include "mpr121.h"
#include <Wire.h>

int val2=0;
int val = 0;
int led2=8;
int led = 13;
int irqpin = 2;  // Digital 2
boolean touchStates[12]; //to keep track of the previous touch states

void setup(){
  pinMode(led2,OUTPUT);
  pinMode(led,OUTPUT);
  pinMode(irqpin, INPUT);
  digitalWrite(irqpin, HIGH); //enable pullup resistor
  
  Serial.begin(9600);
  Wire.begin();

  mpr121_setup();
}

void loop(){
  readTouchInputs();
}


void readTouchInputs(){
  if(!checkInterrupt()){
    
    //read the touch state from the MPR121
    Wire.requestFrom(0x5A,2); 
    
    byte LSB = Wire.read();
    byte MSB = Wire.read();
    
    uint16_t touched = ((MSB << 8) | LSB); //16bits that make up the touch states

    
    for (int i=0; i < 12; i++){  // Check what electrodes were pressed
      if(touched & (1<<i)){
        
     
      
        if(touchStates[i] == 0){
          //pin i was just touched
          Serial.print("pin ");
          Serial.print(i);
          Serial.println(" was just touched");
          
         val = digitalRead(led);
         val2 = digitalRead(led2);
         
          switch (i) {
            case 0:
            if (val == LOW){
              digitalWrite(led,HIGH);
            }
            if(val == HIGH){
              digitalWrite(led,LOW);
            }
            
           break;
           
           case 1:
           if (val2 == LOW){
              digitalWrite(led2,HIGH);
            }
            if(val2 == HIGH){
              digitalWrite(led2,LOW);
            }
           
           break;
            
          }
        
        }else if(touchStates[i] == 1){
          //pin i is still being touched
        }  
      
        touchStates[i] = 1;      
      }
      else{
        if(touchStates[i] == 1){
          Serial.print("pin ");
          Serial.print(i);
          Serial.println(" is no longer being touched");
          
          //pin i is no longer being touched
       }
        
        touchStates[i] = 0;
      }
    
    }
    
  }
}




void mpr121_setup(void){

  set_register(0x5A, ELE_CFG, 0x00); 
  
  // Section A - Controls filtering when data is > baseline.
  set_register(0x5A, MHD_R, 0x01);
  set_register(0x5A, NHD_R, 0x01);
  set_register(0x5A, NCL_R, 0x00);
  set_register(0x5A, FDL_R, 0x00);

  // Section B - Controls filtering when data is < baseline.
  set_register(0x5A, MHD_F, 0x01);
  set_register(0x5A, NHD_F, 0x01);
  set_register(0x5A, NCL_F, 0xFF);
  set_register(0x5A, FDL_F, 0x02);
  
  // Section C - Sets touch and release thresholds for each electrode
  set_register(0x5A, ELE0_T, TOU_THRESH);
  set_register(0x5A, ELE0_R, REL_THRESH);
 
  set_register(0x5A, ELE1_T, TOU_THRESH);
  set_register(0x5A, ELE1_R, REL_THRESH);
  
  set_register(0x5A, ELE2_T, TOU_THRESH);
  set_register(0x5A, ELE2_R, REL_THRESH);
  
  set_register(0x5A, ELE3_T, TOU_THRESH);
  set_register(0x5A, ELE3_R, REL_THRESH);
  
  set_register(0x5A, ELE4_T, TOU_THRESH);
  set_register(0x5A, ELE4_R, REL_THRESH);
  
  set_register(0x5A, ELE5_T, TOU_THRESH);
  set_register(0x5A, ELE5_R, REL_THRESH);
  
  set_register(0x5A, ELE6_T, TOU_THRESH);
  set_register(0x5A, ELE6_R, REL_THRESH);
  
  set_register(0x5A, ELE7_T, TOU_THRESH);
  set_register(0x5A, ELE7_R, REL_THRESH);
  
  set_register(0x5A, ELE8_T, TOU_THRESH);
  set_register(0x5A, ELE8_R, REL_THRESH);
  
  set_register(0x5A, ELE9_T, TOU_THRESH);
  set_register(0x5A, ELE9_R, REL_THRESH);
  
  set_register(0x5A, ELE10_T, TOU_THRESH);
  set_register(0x5A, ELE10_R, REL_THRESH);
  
  set_register(0x5A, ELE11_T, TOU_THRESH);
  set_register(0x5A, ELE11_R, REL_THRESH);
  
  // Section D
  // Set the Filter Configuration
  // Set ESI2
  set_register(0x5A, FIL_CFG, 0x04);
  
  // Section E
  // Electrode Configuration
  // Set ELE_CFG to 0x00 to return to standby mode
  set_register(0x5A, ELE_CFG, 0x0C);  // Enables all 12 Electrodes
  
  
  // Section F
  // Enable Auto Config and auto Reconfig
  /*set_register(0x5A, ATO_CFG0, 0x0B);
  set_register(0x5A, ATO_CFGU, 0xC9);  // USL = (Vdd-0.7)/vdd*256 = 0xC9 @3.3V   set_register(0x5A, ATO_CFGL, 0x82);  // LSL = 0.65*USL = 0x82 @3.3V
  set_register(0x5A, ATO_CFGT, 0xB5);*/  // Target = 0.9*USL = 0xB5 @3.3V
  
  set_register(0x5A, ELE_CFG, 0x0C);
  
}


boolean checkInterrupt(void){
  return digitalRead(irqpin);
}


void set_register(int address, unsigned char r, unsigned char v){
    Wire.beginTransmission(address);
    Wire.write(r);
    Wire.write(v);
    Wire.endTransmission();
}

In the example I attached two leds, to pin 8 and pin 13.

Hope it helps.

4

Insert Quote
Quote
I get an error message about "undeclaired in this scope".
What is "undeclared in this scope"?

i, soz forgot that.

Quote
but this doesnt work either:
Which channel are you using? The first is numbered 0, not 1.

I tried both 0 and 1, both do nothing. The Serial Print command lables that channel as 1 though.

Thanks for the code Gerdid, looks pretty similar only you have used the switch/break command. I might have to try a rewrite with this if I cant just add a line in easily.

Anymore idea would be great! thanks :slight_smile: