Using pduino and Firmata to read values from the Grove I2C Touch sensor

casper

Hi Guys,

I've used pduino in the past to communicate with sensors. I've just got a Grove I2C Touch sensor.

upload-da81648b-8dcb-40b1-b128-9125d6025031

How do I get values from the touch pads into pduino using the standard Firmamta script? I've plugged the sensor into the I2c port on the grove shield base and it seems the standard firmata script deals with the I2C protocol too, but when I set all pins to digi input mode (as well as analog input mode) I get nothing coming through into pduino. Any help would be great

All the best

Casper

alexandros

Is there any sample code that comes along with the sensor? You could probably deal with it without the Firmata, but using the provided code (taken that there is code provided to show how the sensor works).
If there is code, can you post it here?

casper

Hi @alexandros

code is below, if you can figure anything out that would be great !

/* GroveI2CTouchTest.pde - Sample code for the SeeedStudio Grove I2C Touch Sensor
http://seeedstudio.com/wiki/index.php?title=Twig_-_I2C_Touch_Sensor_v0.93b  
Prerequisite: A modification of the Grove I2C Touch sensor is needed Solder a pin to
the INT terminal in the I2C sensor to connect it to one pin in Arduino  Created by
Wendell A. Capili, August 27, 2011. http://wendellinfinity.wordpress.com  
Released into the public domain.*/

#include <Wire.h> // include I2C library
#include <i2c_touch_sensor.h>
#include <MPR121.h>
// include our Grove I2C touch sensor library
// initialize the Grove I2C touch sensor
// IMPORTANT: in this case, INT pin was connected to pin7 of the Arduino 
// (this is the interrupt pin)
i2ctouchsensor touchsensor; // keep track of 4 pads' states
//boolean padTouched[4];
long previousMillis = 0;
long interval = 100;
void setup() 
  {    
    Serial.begin(9600); // for debugging   
    Serial.print("begin to init");  
    Wire.begin(); // needed by the GroveMultiTouch lib     
    touchsensor.initialize(); // initialize the feelers     // initialize the containers     
    //for(int i=0; i<=3; i++) 
    //{          
   // padTouched[i]=false;     
    //}
    
  }
void loop()
{     
   unsigned char MPR_Query=0;
   unsigned long currentMillis = millis();
 if(currentMillis - previousMillis > interval)
  {
    previousMillis = currentMillis;
    touchsensor.getTouchState();
  }
 for (int i=0;i<12;i++)
 {
 if (touchsensor.touched&(1<<i))
    {
    Serial.print("pin ");
        Serial.print(i);
        Serial.println(" was  touched");
         }
 }
}  

/*

  touchsensor.readTouchInputs(); // test read the touch sensors     
// loop through our touch sensors 1 to 4    
  for(int i=0; i<=3; i++)
  {          
// get the touch state based on pin #         
    if(feelers.getTouchState(i)) 
    {              
      if(!padTouched[i]) 
        {                    // print in serial that it was touched             
        Serial.print("Pad ");                   
        Serial.print(i);                               
        Serial.println(" was touched");             
        }              
// flag the touch sensor state              
    padTouched[i]=true;         
     }          
    else 
    {             
    if(padTouched[i]) 
    {                    
      // print in serial that it was released                                      
      Serial.print("Pad ");                  
      Serial.print(i);                               
      Serial.println(" was released");            
    }               // reset the touch sensor state                      
    padTouched[i]=false;        
    }    
  }*/

alexandros

You can use this code with [comport] and an abstraction I made, [serial_print] (if you're on extended then use [serial_print_extended]), which you can get from my GitHub https://github.com/alexdrymonitis/Arduino_Pd

The only modification you'll need to do is to replace some white spaces. In the loop() function, the code reads:
Serial.print("pin ");
Serial.print(i);
Serial.println(" was touched");

change the last line with:
Serial.println(" was_touched");

Do the same for further down where it reads:
Serial.print("pad ");
Serial.print(i);
Serial.println(" was_touched");

and close to the end where it reads:
Serial.println(" was_released");

In [serial_print] the white space is read as a separator (it can be used in a string, but with this code it's not really functional).
Lastly, int the setup() function there's a line that reads:
Serial.print("begin to init");
put two forward slashes at the beginning of the line (//) to comment it out, as this string is not very helpful in Pd. If you really need it, you'll need to modify it.

In Pd, do the following:

[comport 1 9600] <- the 1st argument is the port number and the 2nd the baud rate (the 1st might be different in your computer)
|
[serial_print]
| /
[send]

[r pin]
|
[print]

[r pad]
|
[print]

You'll receive data using the strings "pin" and "pad" in [receive]s. Use print to see the data that comes out and use that data as you wish.

Read [serial_print]'s help patch to see how it works.

casper

Hi @alexandros thanks for all this. Unfortunately the sketch won't compile I keep getting
PD_i2c_touch.ino:10:20: fatal error: MPR121.h: No such file or directory. I've put the header file MPR121.h in the same folder as PD_i2c_touch.ino, but it still seems at arduino IDE can't access it. Sorry if this is basic stuff but do you have any ideas regarding how to resolve this?

cheers

Casper

alexandros

Looking here, it looks like the header file is written in lower case letters. In case the header file you have is also in lower case letters, try changing this line:
#include <MPR121.h>
to:
#include <mpr121.h>
and see what happens..

casper

Hi @alexandros Yep you were right, the header file needed lower-case! Thank you so much my sensor is now working with the mods to the sketch as well as using your PD abstractions. .. Is there a way to use your abstractions with the Firmata sketch to control this Grove i2C touch sensor? Reason being, I need to teach some of my students this environment and I think it would be good for them (if possible) to use the standard Firmata with all sensors (including I2c) to missing out the ardunio coding aspect and just interact with the data in Pd using your abstractions? I'm not get with arduino code myself so having firmata "solve that problem" would be a good starting place for now. Is it possible to use Firmata with your abstractions?

all the ebst

Casper

alexandros

Nope, these abstractions where built in order to be able to use existing Arduino code (most of which uses the Serial.print() function for serial communication) with the bare minimum modifications (or even, no modifications at all).

The only thing you need to take care of is the separator of the values being sent over serial. If you're using the space as a separator (by default, space, comma, and horizontal tab are separators, but you can use any of these three in any combination), make sure you include a space only when you want to break a message. For these reason I told you that " was touched" should be replaced by " was_touched". In this case, the space at the beginning of the string is the separator, and the string is now connected with an underscore.

It's pretty easy, if you spend some time with it.

Firmata was built in order to be able to program the Arduino from an external software (Pd, for example). It has its own abstraction, [arduino], and its a stand-alone interface. No room for [serial_print] there...

casper

HI @alexandros no worries I thought this might be the case. Thanks to all your help though, I'm now up and running thanks to your abstractions and your input

all the best

Casper