Switch/case not working

Projects Programming
1

Key is a character from a keyboard, which works ok, but the case doesnt seem to be switching the value of sp_period. (the Serial.println doesnt execute when key is 5.

switch (key) {
case 0: sp_period = 10000; break; // stop motor!
case 1: sp_period = 833; break;
case 2: sp_period = 625; break;
case 3: sp_period = 416; break;
case 4: sp_period = 294; break;
case 5: sp_period = 188; Serial.println (key); break;
case 6: sp_period = 156; break;
default: sp_period = 10000; break;
}

2

Hello
What datatype is used for the variable KEY?

3

case 0 is redundant as it's identical in action to the default case.
Unless you're trying to switch an enum or a char or something odd, this switch should work.
Can you expand your code please, the problem may be seen here but it likely happens elsewhere.

4

You probably need the cases to be ascii characters (encapsulated in '') and not integers:

switch (key) {
case '0': sp_period = 10000; break; // stop motor!
case '1': sp_period = 833; break;
...
default: sp_period = 10000; break;
}
5

@v_mad you may be confusing the 5 in your switch statement - which is a integer, with the character '5' which is actually stored as the integer 53 (see ASCII character tables).

EDIT: Or change the comparison in the case statement as @Danois90 just pointed out.

6

The keyboard key that has a 5 outputs the value 53 which is equivalent to '5' .

If you doubt this, put Serial.println(key); as the next line after after you get key.

7

I do not believe that to be true.

8

Why is that?

9 
void setup() {
  uint8_t x = 0;

  Serial.begin(115200);
  delay(1000);

  switch (x) {
    case 0:
      Serial.println("Zero");
      break;

    default:
      Serial.println("Default");
      break;
  }
}

void loop() {
}

Serial Monitor Output:

Zero

EDIT:
Never mind. I think I misunderstood your meaning. Thought you were saying that using 'default:' is the same as using 'case 0:'
My bad.

1 Like
10

Thank you to all. You were right, the key was a char type, so I needed to use '1' rather than 1 etc. Now working fine.
I am very rusty on coding having had a 3+ year break, but I hope to be able to get back up to speed soon.
Cheers

1 Like
11

I was hoping that was the mistake. I now understand why you initially thought that though :smiley:

12

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