I want to build a very simple synth using the MPR121 capacitive touch sensor breakout and the tone values stored in 'pitches.h'.
I followed the tutorial here (http://bildr.org/2011/05/mpr121_arduino/) to get the capacitance sensors working and they work fine using this code
#include "mpr121.h"
#include <Wire.h>
int irqpin = 2; // Digital 2
boolean touchStates[12]; //to keep track of the previous touch states
void setup(){
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");
}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();
}
The problem is, the tutorial says that you can use the sensors to trigger specific events (like sound) with the following addition to the code and I cant get it to compile...
if(touchStates[i] == 0){
//pin i was just touched
Serial.print("pin ");
Serial.print(i);
Serial.println(" was just touched");
switch (i) {
case 0:
//0 was touched
break;
case 1:
//1 was touched
break;
case 2:
//2 was touched
break;
case 3:
//3 was touched
}
}
I really like the code that was written for the sensors because they can read multiple sensors at on time so I would be able to play chords.