Thanks for the replies!
@zhomeslice
Thank you for your help!
I had some flickering problems when I wanted to dim less powerful lamps. This might be due to the signal to turn on the triac turning off too late like you mentioned.
I used the dimming levels 40-55-70-85-100-115 because everything under 40 didn't change the brightness of my lamps anymore (I use dimmable 12V AC LED lamps via a 230V to 12V transformer). I also don't want the lamps to be able to turn completely off. I want to add a physical switch before the triac circuit. Like that, I can come into the room and turn on the light switch to make the lights go on without always having to take my phone. 
I have one more problem that I couldn't figure out after searching around. I don't understand how I have to differentiate between the 5 channels when I want them to be at a specific dimming level. I am talking about this part of the code:
if (!strcmp(inStr,"115a")){
{
dim = 115; // not working of course
}
}
if (!strcmp(inStr,"100a")){
{
dim = 100;
}
}
if (!strcmp(inStr,"85a")){
{
dim = 85;
}
}
if (!strcmp(inStr,"70a")){
{
dim = 70;
}
}
if (!strcmp(inStr,"55a")){
{
dim = 55;;
}
}
if (!strcmp(inStr,"40a")){
{
dim = 40;
}
}
If I send for example the word '115a' via the bluetooth module, I want the lamp on channel 1 (pin 3) to dim to level 115. I can't make that to work.
This is the code that I have right now:
#include <TimerOne.h> // Avaiable from http://www.arduino.cc/playground/Code/Timer1
volatile int i=0; // Variable to use as a counter of dimming steps. It is volatile since it is passed between interrupts
volatile boolean zero_cross=0; // Flag to indicate we have crossed zero
volatile int Pins[5] = {3, 4, 5, 6, 7}; // list Triac pin as output
int rx=0;
volatile int dim[6] = {40, 55, 70, 85, 100, 115}; // list of Dimming level (0-128) 0 = on, 128 = 0ff
int freqStep = 75; // This is the delay-per-brightness step in microseconds. It allows for 128 steps
char inSerial[15];
void setup() { // Begin setup
Serial.begin(9600);
pinMode(rx, INPUT);
pinMode(Pins[5], OUTPUT); // Set the Triac pin as output
attachInterrupt(0, zero_cross_detect, RISING); // Attach an Interupt to Pin 2 (interupt 0) for Zero Cross Detection
Timer1.initialize(freqStep); // Initialize TimerOne library for the freq we need
Timer1.attachInterrupt(dim_check, freqStep); // Go to dim_check procedure every 75 uS (50Hz) or 65 uS (60Hz)
// Use the TimerOne Library to attach an interrupt
}
void zero_cross_detect() {
zero_cross = true; // set flag for dim_check function that a zero cross has occured
i=0; // stepcounter to 0.... as we start a new cycle
digitalWrite(Pins[5], LOW);
}
// Turn on the TRIAC at the appropriate time
// We arrive here every 75 (65) uS
// First check if a flag has been set
// Then check if the counter 'i' has reached the dimming level
// if so.... switch on the TRIAC and reset the counter
void dim_check() { // this is automatically triggered by a timer
i++; // this will get reset to zero with zero_cross_detect()
for (int pin = 0; pin < 5; pin++) { // 0~4 gives us 5 counts for our 5 outputs
if (i >= dim[pin]) { // Lets latch the triac
if(dim[pin] < 128) digitalWrite(Pins[pin], HIGH); // turn on light (if dim is 128 we want it off so lets not even try to turn it on) }
if (i >= dim[pin]+1) { // We have latched the triac and now we are 75 uS (50Hz) or 65 uS (60Hz) later. The triac latches until it crosses zero so we can turn off the enable
if(dim[pin] > 0 ) digitalWrite(Pins[pin], LOW); // if we are at 0 we need to trip this asap so lets not turn the request of }
}
}
}
}
void loop(){
int i=0;
delay(500);
if (Serial.available() > 0) {
while (Serial.available() > 0) {
inSerial[i]=Serial.read();
i++;
}
inSerial[i]='\0';
Check_Protocol(inSerial);
}}
void allpinslow()
{
digitalWrite(Pins[5], LOW);
}
void Check_Protocol(char inStr[]){
int i=0;
Serial.println(inStr);
if (!strcmp(inStr,"115a")){
{
dim = 115;
}
}
if (!strcmp(inStr,"100a")){
{
dim = 100;
}
}
if (!strcmp(inStr,"85a")){
{
dim = 85;
}
}
if (!strcmp(inStr,"70a")){
{
dim = 70;
}
}
if (!strcmp(inStr,"55a")){
{
dim = 55;;
}
}
if (!strcmp(inStr,"40a")){
{
dim = 40;
}
}
}
Thank you once again!