State Machine with If/Else?

Question

I am trying to make a state machine with if/else. But some of the code does not seem to be executing. I have information being displayed on an LCD screen so I know where it is, and it stays on Todo=1 and does not go to the next state. I have tried using switch/case and it works. But I think it might be better for my project if I use if/else. Can I do this using if/else?

Void loop{
 if (state == PLAY) {
 Todo = 1;
 Mastermachine(Todo);
 } else if (state == TRYAGIN) {
 }
}
void Mastermachine(int Todo) {
 if (Todo == 1) {
 lcd.setCursor(16, 2);
 lcd.print(String(Todo));
 SongSeq[largestindex];
 for (int index = 0; index < largestindex; index++) {
 SongSeq[index]();
 }
 Todo = 2;
 } else if (Todo == 2) {
 for (learnindex = 0; learnindex < largestindex;) {
 MIDI.read();
 if (learnindex >= largestindex) {
 Todo = 3;
 }
 lcd.setCursor(16, 2);
 lcd.print(String(Todo));
 }
 } else if (Todo == 3) {
 if (array_cmp(learn, note, largestindex, largestindex) == true) {
 largestindex++;
 delay(2000);
 Todo = 1;
 } else {
 delay(2000);
 Todo = 1;
 }
 lcd.setCursor(16, 2);
 lcd.print(String(Todo));
 }
}

• Michel Keijzers: Consider a switch statement instead of the if/else statements.
• Mikael Patel: Make the state a global variable. Todo is lost after each call of MasterMachine() (if you do no introduce a loop).

Answer 1

Inside Mastermachine(), Todo is a copy whatever is passed as its paramter. Even if you make a global named Todo, it will be 'hidden' by the parameter of the same name. That parameter goes out of scope - disappears - when Mastermachine() exits, including any changes made to it within the function.

There are a few choices to accomplish what you want to do, but the easiest is probably to make a global Todo and get rid of the parameter Todo in Mastermachine(); i.e., make it void Mastermachine(void). Then the name Todo inside the function will refer to the global by that name.

Answer 2

Your loop executes continually, always setting the state to 1.....

The called state machine supposedly changes the state, but it get set back to 1 every time the loop executes.

The loop program needs to do the state changes, not the masternachine function.

• Hjhk90: would moving Todo=1 somewhere else fix that issue ?
• mico: If you want to have Todo=1 set only once, place it in setup.