Hey all,
I am kind of stuck with a little detail of my code, where I want to use a global variable to be able to be used and changed by a function with several if-else-statements. I have several Capacitive Sensors that each have a letter prescribed to them that gets printed out by the Serial Monitor.
I have the variable char prev for the previous letter that the function updateCapacitiveSensors printed and I want it to only print the new letter, if it is a different one than the one before, so that if I touch one Sensor a little longer, it does not print it more than once.
With comparing the prev variable with the new letter I wanted to archieve this, but I think that it only changes the variable locally. So I changed the void updateCapacitiveSensors function to a char updateCapacitiveSensors function in order to pass the value for prev, but I think I did it wrong, but don't know where exactly
this is my complete code:
#include <CapacitiveSensor.h>
#include <arduino.h>
int main() {
init();
Serial.begin(9600);
//general loop for the sensors for the different regions
static char prev='x';
while (true) {
prev= updateCapacitiveSensors(prev);
delay(300);
}
}
//decades
int inpin = A0; // input pin for potentiometer
int in = 0;
//regions
int threshold = 60;
//1 capacitive sensor per region
CapacitiveSensor cs_a5_a1 = CapacitiveSensor(A5, A1); //define region here // GERMANY 10M resistor between pins A5 & 0, pin 0 is sensor pin
CapacitiveSensor cs_a5_a2 = CapacitiveSensor(A5, A2); //define region here // FRANCE 10M resistor between pins A5 & 1, pin 1 is sensor pin
CapacitiveSensor cs_a5_2 = CapacitiveSensor(A5, 2); //define region here // GREAT BRITAIN 10M resistor between pins A5 & 2, pin 2 is sensor pin
CapacitiveSensor cs_a5_3 = CapacitiveSensor(A5, 3); //define region here // SPAIN + PORTUGAL 10M resistor between pins A5 & 3, pin 3 is sensor pin
CapacitiveSensor cs_a5_4 = CapacitiveSensor(A5, 4); //define region here // ITALY 10M resistor between pins A5 & 4, pin 4 is sensor pin
CapacitiveSensor cs_a5_5 = CapacitiveSensor(A5, 5); //define region here // AFRICA 10M resistor between pins A5 & 5, pin 5 is sensor pin
CapacitiveSensor cs_a5_6 = CapacitiveSensor(A5, 6); //define region here // SCANDINAVIA 10M resistor between pins A5 & 6, pin 6 is sensor pin
CapacitiveSensor cs_a5_7 = CapacitiveSensor(A5, 7); //define region here // ASIA 10M resistor between pins A5 & 7, pin 7 is sensor pin
CapacitiveSensor cs_a5_8 = CapacitiveSensor(A5, 8); //define region here // AUSTRALIA 10M resistor between pins A5 & 8, pin 8 is sensor pin
CapacitiveSensor cs_a5_9 = CapacitiveSensor(A5, 9); //define region here // SOUTH EAST 10M resistor between pins A5 & 9, pin 9 is sensor pin
CapacitiveSensor cs_a5_10 = CapacitiveSensor(A5, 10); //define region here // RUSSIA 10M resistor between pins A5 & 10, pin 10 is sensor pin
CapacitiveSensor cs_a5_11 = CapacitiveSensor(A5, 11); //define region here // SOUTH AMERICA 10M resistor between pins A5 & 11, pin 11 is sensor pin
CapacitiveSensor cs_a5_12 = CapacitiveSensor(A5, 12); //define region here // USA + CANADA 10M resistor between pins A5 & 12, pin 12 is sensor pin
CapacitiveSensor cs_a5_13 = CapacitiveSensor(A5, 13); //define region here // INDIA 10M resistor between pins A5 & 13, pin 13 is sensor pin
char updateCapacitiveSensors(char &prev) {
//read sensor input from the cap. sensors
long sense0 = cs_a5_a1.capacitiveSensor(30); //GERMANY
long sense1 = cs_a5_a2.capacitiveSensor(30); //FRANCE
long sense2 = cs_a5_2.capacitiveSensor(30); //GREAT BRITAIN
long sense3 = cs_a5_3.capacitiveSensor(30); //SPAIN + PORTUGAL
long sense4 = cs_a5_4.capacitiveSensor(30); //ITALY
long sense5 = cs_a5_5.capacitiveSensor(30); //AFRICA
long sense6 = cs_a5_6.capacitiveSensor(30); //SCANDINAVIA
long sense7 = cs_a5_7.capacitiveSensor(30); //ASIA
long sense8 = cs_a5_8.capacitiveSensor(30); //AUSTRALIA
long sense9 = cs_a5_9.capacitiveSensor(30); //SOUTH EAST
long sense10 = cs_a5_10.capacitiveSensor(30); //RUSSIA
long sense11 = cs_a5_11.capacitiveSensor(30); //SOUTH AMERICA
long sense12 = cs_a5_12.capacitiveSensor(30); //USA +CANADA
long sense13 = cs_a5_13.capacitiveSensor(30); //INDIA
//read sensor input from the potentiometer
in= analogRead(inpin);
int printin= 10;
if (in<100){
printin=0;
}
else if (in<200){
printin=1;
}
else if (in<300){
printin=2;
}
else if (in<400){
printin=3;
}
else if (in<500){
printin=4;
}
else if (in<600){
printin=5;
}
else if (in<700){
printin=6;
}
else if (in<800){
printin=7;
}
else if (in<900){
printin=8;
}
else{
printin=9;
}
if (sense0 > threshold) {
if (prev =='g'){
}
else{
Serial.println(printin);
Serial.println('g');
return 'g';
}
}
if (sense1 > threshold) {
if (prev =='f'){
}
else{
Serial.println(printin);
Serial.println('f');
return 'f';
}
}
else if (sense2 > threshold) {
if (prev =='b'){
}
else{
Serial.println(printin);
Serial.println('b');
return 'b';
}
}
else if (sense3 > threshold) {
if (prev =='s'){
}
else{
Serial.println(printin);
Serial.println('s');
return 's';
}
}
else if (sense4 > threshold) {
if (prev =='i'){
}
else{
Serial.println(printin);
Serial.println('i');
return prev='i';
}
}
else if (sense5 > threshold) {
if (prev =='o'){
}
else{
Serial.println(printin);
Serial.println('a');
return 'a';
}
}
else if (sense6 > threshold) {
if (prev =='v'){
}
else{
Serial.println(printin);
Serial.println('v');
return 'v';
}
}
else if (sense7 > threshold) {
if (prev =='c'){
}
else{
Serial.println(printin);
Serial.println('c');
return prev='c';
}
}
else if (sense8 > threshold) {
if (prev =='t'){
}
else{
Serial.println(printin);
Serial.println('t');
return 't';
}
}
else if (sense9 > threshold) {
if (prev =='e'){
}
else{
Serial.println(printin);
Serial.println('e');
return 'e';
}
}
else if (sense10 > threshold) {
if (prev =='r'){
}
else{
Serial.println(printin);
Serial.println('r');
return 'r';
}
}
else if (sense11 > threshold) {
if (prev =='o'){
}
else{
Serial.println(printin);
Serial.println('o');
return 'o';
}
}
else if (sense12 > threshold) {
if (prev =='u'){
}
else{
Serial.println(printin);
Serial.println('u');
return 'u';
}
}
else if (sense13 > threshold) {
if (prev =='n'){
}
else{
Serial.println(printin);
Serial.println('n');
return 'n';
}
}
}
I would be glad if someone could point me in the right direction 
Thank you!