MPR121 - Arduino - Max Data Flow

JennaRachelle · May 12, 2014, 3:58pm

Hi All,

I’m having problems with my Arduino code - have come up against a brick wall and am hoping someone here might be able to help me or point me in the right direction…

I’ve been using Arduino and Max for two years but for standalone projects. I’m not working on an installation that uses both and establishes serial communication between the two programs. I have an Arduino Mega, with an MPR121 chip (https://www.sparkfun.com/products/9695) and it’s 12 electrodes/sensors attached.

Below is the Arduino code. In the Arduino Serial monitor I can see which sensor is being touched. I need this data in Max, but all Max can do is tell that a sensor is being touched, not which sensor specifically. Everything makes sense from the Max end - so I believe my code is not actually feeding Max the correct sensor data and I’m afraid this is where my Arduino code knowledge is running short…

Below is the code.

Thank you os much for you time and thoughts.

J.

/*!

@filename capactivite_prox_sensor_mpr121.ino
@author Julio Terra
@date May 22, 2013
@version 1.0.1
Please check-out the read-me for details about how to hook-up the Arduino and the MPR121
breakout boards.

*/

#include “mpr121.h”

#include <Wire.h>

#define SENSORS 13

#define TOU_THRESH 0x1F

#define REL_THRESH 0x1A

#define PROX_THRESH 0x3f

#define PREL_THRESH 0x3c

// variables: capacitive sensing

bool touchStates[SENSORS]; // holds the current touch/prox state of all sensors

bool activeSensors[SENSORS] = {1,1,1,1,1,1,1,1,1,1,1,1,1}; // holds which sensors are active (0=inactive, 1=active)

bool newData = false; // flag that is set to true when new data is available from capacitive sensor

int irqpin = 2; // pin that connects to notifies when data is available from capacitive sensor

void setup(){

// attach interrupt to pin – interrupt 1 is on pin 2 of the arduino (confusing I know)

attachInterrupt(0, dataAvailable, FALLING);

// set-up the Serial and I2C/Wire connections

Serial.begin(9600);

Wire.begin();

// set the registers on the capacitive sensing IC

setupCapacitiveRegisters();

}

void loop(){

readCapacitiveSensor();

}

/**

dataAvailable Callback method that runs whenever new data becomes available on from the capacitive sensor.
This method was attached to the interrupt on pin 2, and is called whenever that pins goes low.

*/

void dataAvailable() {

newData = true;

}

/**

readCapacitiveSensor Reads the capacitive sensor values from the MP121 IC. It makes a request to
the sensor chip via the I2C/Wire connection, and then parses the sensor values which are stored on
the first 13 bits of the 16-bit response msg.

*/

void readCapacitiveSensor(){

if(newData){

//read the touch state from the MPR121

Wire.requestFrom(0x5A,2);

byte tLSB = Wire.read();

byte tMSB = Wire.read();

uint16_t touched = ((tMSB << smiley-cool | tLSB); //16bits that make up the touch states

for (int i = 0; i < SENSORS; i++){ // Check what electrodes were pressed

if (activeSensors == 0) continue;

char sensor_id = {”,”,”};

switch (i) {

case 12:

sensor_id[0] = ‘P’;

break;

default:

if (i < 10) {

sensor_id[0] = char( i+48 );

}

else if (i < 12) {

sensor_id[0] = char(’1′);

sensor_id[1] = char( ( i % 10 ) + 48 );

}

if (sensor_id != ”) {

// read the humidity level

// if current sensor was touched (check appropriate bit on touched var)

if(touched & (1<<i)){

// if current pin was not previously touched send a serial message

if(touchStates == 0){

Serial.print(sensor_id);

Serial.print(“:”);

Serial.println(“touched”);

}

touchStates = 1;

} else {

// if current pin was just touched send serial message

if(touchStates == 1){

Serial.print(sensor_id);

Serial.print(“:”);

Serial.println(“not touched”);

}

touchStates = 0;

}

newData = false;

}

/**

setupCapacitiveRegisters Updates all of configurations on the MP121 capacitive sensing IC. This includes
setting levels for all filters, touch and proximity sensing activation and release thresholds, debounce,
and auto-configurations options. At the end it activates all of the electrodes.

*/

void setupCapacitiveRegisters(){

set_register(0x5A, ELE_CFG, 0×00);

// Section A – filtering when data is > baseline.

// touch sensing

set_register(0x5A, MHD_R, 0×01);

set_register(0x5A, NHD_R, 0×01);

set_register(0x5A, NCL_R, 0×00);

set_register(0x5A, FDL_R, 0×00);

// prox sensing

set_register(0x5A, PROX_MHDR, 0xFF);

set_register(0x5A, PROX_NHDAR, 0xFF);

set_register(0x5A, PROX_NCLR, 0×00);

set_register(0x5A, PROX_FDLR, 0×00);

// Section B – filtering when data is < baseline.

// touch sensing

set_register(0x5A, MHD_F, 0×01);

set_register(0x5A, NHD_F, 0×01);

set_register(0x5A, NCL_F, 0xFF);

set_register(0x5A, FDL_F, 0×02);

// prox sensing

set_register(0x5A, PROX_MHDF, 0×01);

set_register(0x5A, PROX_NHDAF, 0×01);

set_register(0x5A, PROX_NCLF, 0xFF);

set_register(0x5A, PROX_NDLF, 0xFF);

// 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 touch filter Configuration

set_register(0x5A, FIL_CFG, 0×04);

// Section E – Set proximity sensing threshold and release

set_register(0x5A, PRO_T, PROX_THRESH); // sets the proximity sensor threshold

set_register(0x5A, PRO_R, PREL_THRESH); // sets the proximity sensor release

// Section F – Set proximity sensor debounce

set_register(0×59, PROX_DEB, 0×50); // PROX debounce

// Section G – Set Auto Config and Auto Reconfig for prox sensing

set_register(0x5A, ATO_CFGU, 0xC9); // USL = (Vdd-0.7)/vdd*256 = 0xC9 @3.3V

set_register(0x5A, ATO_CFGL, 0×82); // LSL = 0.65*USL = 0×82 @3.3V

set_register(0x5A, ATO_CFGT, 0xB5); // Target = 0.9*USL = 0xB5 @3.3V

set_register(0x5A, ATO_CFG0, 0x0B);

// Section H – Start listening to all electrodes and the proximity sensor

set_register(0x5A, ELE_CFG, 0x3C);

}

/**

set_register Sets a register on a device connected via I2C. It accepts the device’s address,
register location, and the register value.
@param address The address of the I2C device
@param r The register’s address on the I2C device
@param v The new value for the register

*/

void set_register(int address, unsigned char r, unsigned char v){

Wire.beginTransmission(address);

Wire.write(r);

Wire.write(v);

Wire.endTransmission();

}

Mee_n_Mac · May 14, 2014, 3:58am

How does Max know which sensors were touched ? What data is it looking for ?

FWIW you’ll get more responses when the code is more readable.

/*!
* @filename capactivite_prox_sensor_mpr121.ino
* @author Julio Terra
* @date May 22, 2013
* @version 1.0.1
*
* Please check-out the read-me for details about how to hook-up the Arduino and the MPR121
* breakout boards.
*
*/

#include “mpr121.h”
#include <Wire.h>

#define SENSORS 13
#define TOU_THRESH 0x1F
#define REL_THRESH 0x1A
#define PROX_THRESH 0x3f
#define PREL_THRESH 0x3c

// variables: capacitive sensing
bool touchStates[SENSORS]; // holds the current touch/prox state of all sensors
bool activeSensors[SENSORS] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}; // holds which sensors are active (0=inactive, 1=active)
bool newData = false; // flag that is set to true when new data is available from capacitive sensor
int irqpin = 2; // pin that connects to notifies when data is available from capacitive sensor

void setup() {

  // attach interrupt to pin – interrupt 1 is on pin 2 of the arduino (confusing I know)
  attachInterrupt(0, dataAvailable, FALLING);

  // set-up the Serial and I2C/Wire connections
  Serial.begin(9600);
  Wire.begin();

  // set the registers on the capacitive sensing IC
  setupCapacitiveRegisters();
}

void loop() {
  readCapacitiveSensor();
}

/**
* dataAvailable Callback method that runs whenever new data becomes available on from the capacitive sensor.
* This method was attached to the interrupt on pin 2, and is called whenever that pins goes low.
*/
void dataAvailable() {
  newData = true;
}

/**
* readCapacitiveSensor Reads the capacitive sensor values from the MP121 IC. It makes a request to
* the sensor chip via the I2C/Wire connection, and then parses the sensor values which are stored on
* the first 13 bits of the 16-bit response msg.
*/
void readCapacitiveSensor() {
  if (newData) {
    //read the touch state from the MPR121
    Wire.requestFrom(0x5A, 2);
    byte tLSB = Wire.read();
    byte tMSB = Wire.read();
    uint16_t touched = ((tMSB << smiley - cool | tLSB); //16bits that make up the touch states

    for (int i = 0; i < SENSORS; i++) { // Check what electrodes were pressed
    if (activeSensors == 0) continue;
      char sensor_id [] = {”, ”, ”};
      switch (i) {
        case 12:
          sensor_id[0] = ‘P’;
          break;
        default:
          if (i < 10) {
            sensor_id[0] = char( i + 48 );
          }
          else if (i < 12) {
            sensor_id[0] = char(’1′);
            sensor_id[1] = char( ( i % 10 ) + 48 );
          }
      }
      if (sensor_id != ”) {
        // read the humidity level

        // if current sensor was touched (check appropriate bit on touched var)
        if (touched & (1 << i)) {
          // if current pin was not previously touched send a serial message
          if (touchStates == 0) {
            Serial.print(sensor_id);
Serial.print(“: ”);
            Serial.println(“touched”);
          }
          touchStates = 1;
        } else {
          // if current pin was just touched send serial message
          if (touchStates == 1) {
            Serial.print(sensor_id);
Serial.print(“: ”);
            Serial.println(“not touched”);
          }
          touchStates = 0;
        }
      }
    }
    newData = false;
  }
}

/**
* setupCapacitiveRegisters Updates all of configurations on the MP121 capacitive sensing IC. This includes
* setting levels for all filters, touch and proximity sensing activation and release thresholds, debounce,
* and auto-configurations options. At the end it activates all of the electrodes.
*/
void setupCapacitiveRegisters() {

  set_register(0x5A, ELE_CFG, 0×00);

  // Section A – filtering when data is > baseline.
  // touch sensing
  set_register(0x5A, MHD_R, 0×01);
  set_register(0x5A, NHD_R, 0×01);
  set_register(0x5A, NCL_R, 0×00);
  set_register(0x5A, FDL_R, 0×00);

  // prox sensing
  set_register(0x5A, PROX_MHDR, 0xFF);
  set_register(0x5A, PROX_NHDAR, 0xFF);
  set_register(0x5A, PROX_NCLR, 0×00);
  set_register(0x5A, PROX_FDLR, 0×00);

  // Section B – filtering when data is < baseline.
  // touch sensing
  set_register(0x5A, MHD_F, 0×01);
  set_register(0x5A, NHD_F, 0×01);
  set_register(0x5A, NCL_F, 0xFF);
  set_register(0x5A, FDL_F, 0×02);

  // prox sensing
  set_register(0x5A, PROX_MHDF, 0×01);
  set_register(0x5A, PROX_NHDAF, 0×01);
  set_register(0x5A, PROX_NCLF, 0xFF);
  set_register(0x5A, PROX_NDLF, 0xFF);

  // 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 touch filter Configuration
  set_register(0x5A, FIL_CFG, 0×04);

  // Section E – Set proximity sensing threshold and release
  set_register(0x5A, PRO_T, PROX_THRESH); // sets the proximity sensor threshold
  set_register(0x5A, PRO_R, PREL_THRESH); // sets the proximity sensor release

  // Section F – Set proximity sensor debounce
  set_register(0×59, PROX_DEB, 0×50); // PROX debounce

  // Section G – Set Auto Config and Auto Reconfig for prox sensing
  set_register(0x5A, ATO_CFGU, 0xC9); // USL = (Vdd-0.7)/vdd*256 = 0xC9 @3.3V
  set_register(0x5A, ATO_CFGL, 0×82); // LSL = 0.65*USL = 0×82 @3.3V
  set_register(0x5A, ATO_CFGT, 0xB5); // Target = 0.9*USL = 0xB5 @3.3V
  set_register(0x5A, ATO_CFG0, 0x0B);

  // Section H – Start listening to all electrodes and the proximity sensor
  set_register(0x5A, ELE_CFG, 0x3C);
}

/**
* set_register Sets a register on a device connected via I2C. It accepts the device’s address,
* register location, and the register value.
* @param address The address of the I2C device
* @param r The register’s address on the I2C device
* @param v The new value for the register
*/
void set_register(int address, unsigned char r, unsigned char v) {
  Wire.beginTransmission(address);
  Wire.write(r);
  Wire.write(v);
  Wire.endTransmission();
}

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MPR121 - Arduino - Max Data Flow

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