1

I want to know how I can use case statement for each array.

Below is my code:

int incomingByte = 0;

void setup()
{
  Serial.begin(115200);
  for (int thisPin = 2; thisPin < 6; thisPin++)
  {
    pinMode(thisPin, OUTPUT);
  }
}

void loop()
{
  int button1[] = {0xFF, 0x04, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05};
  int button2[] = {0xFF, 0x04, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06};
  int button3[] = {0xFF, 0x04, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08};
  int button4[] = {0xFF, 0x04, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0C};

  if (Serial.available() > 0)
  {
    incomingByte = Serial.read();
  }

  switch (incomingByte)
  {
    case button1:
      digitalWrite(2, HIGH);
      break;
    case button2:
      digitalWrite(3, HIGH);
      break;
    case button3:
      digitalWrite(4, HIGH);
      break;
    case button4:
      digitalWrite(5, HIGH);
      break;
    default:
      for (int thisPin = 2; thisPin < 6; thisPin++)
      {
        digitalWrite(thisPin, LOW);
      }
  }
}
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2 Answers 2

Reset to default
0

Not checked/compiled, just to give an idea.

/* One button message is 12 bytes, it is assumed that all received messages are 12 bytes. If note, you have to check later differently. */
#define MSG_SIZE 11   
byte incomingBytes[MSG_SIZE]; /* Storage for 11 bytes */
byte index = 0; /* Current byte to set within incomingBytes */

void setup()
{
  Serial.begin(115200);
  for (int thisPin = 2; thisPin < 6; thisPin++)
  {
    pinMode(thisPin, OUTPUT);
  }
}

void loop()
{
  if (Serial.available() > 0)
  {
    /* Store the next incoming byte. Assume 0xFF is the start of a message. */
    byte incoming_byte = Serial.read();
    if (incoming_byte == 0xFF)
    {
      index = 0;
    }

    incomingBytes[index] = incoming_byte;
    index++;
    if (index >= MSG_SIZE)
    {
       check_message();
       index = 0;
    }
  }
}

/* Checks which button is pressed and performs an action based on the 
pressed button. */
void check_message()
{
  case check_button_pressed())
  {
    case 1:
      digitalWrite(2, HIGH);
      break;
    case 2:
      digitalWrite(3, HIGH);
      break;
    case 3:
      digitalWrite(4, HIGH);
      break;
    case 4:
      digitalWrite(5, HIGH);
      break;
    default:
      for (int thisPin = 2; thisPin < 6; thisPin++)
      {
        digitalWrite(thisPin, LOW);
      }
  }
} 

/* Checks which button is pressed by comparing 11 incoming bytes to the
four buttons to be checked. Returns -1 for an illegal message/unsupported
button and 1, 2, 3 or 4 for the pressed button. */
int check_button_pressed()
{
  int button_pressed = -1;
  if ((incomingBytes[0] == 0xFF) &&
      (incomingBytes[1] == 0x04) &&
      (incomingBytes[3] == 0x00) &&
      (incomingBytes[4] == 0x00) &&
      (incomingBytes[5] == 0x00) &&
      (incomingBytes[6] == 0x00) &&
      (incomingBytes[7] == 0x00) &&
      (incomingBytes[8] == 0x00) &&
      (incomingBytes[9] == 0x00))
  {
    if ((incomingBytes[2] == 0x01) && (incomingBytes[10] == 0x05))
    {
      button_pressed = 1;
    }
    else if ((incomingBytes[2] == 0x02) && (incomingBytes[10] == 0x06))
    {
      button_pressed = 2;
    }
    else if ((incomingBytes[2] == 0x04) && (incomingBytes[10] == 0x08))
    {
      button_pressed = 3;
    }
    else if ((incomingBytes[2] == 0x08) && (incomingBytes[10] == 0x0C))
    {
      button_pressed = 4;
    }
  }
  return button_pressed;
}
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4
  • I'd add something to explicitly re-sync the stream when 0xFF is received, to handle variable length messages and cases where the serial connection is established in mid-message, but otherwise this is a good approach.
    – Russell Borogove
    Jan 14, 2018 at 14:48
  • True, this is in case all messages are same length. But I don't know what the start of a message is, probably 0xFF. If so, if character is encounter, set Index to 0
    – Michel Keijzers
    Jan 14, 2018 at 15:34
  • @RussellBorogove I adapted the code for it.
    – Michel Keijzers
    Jan 14, 2018 at 15:37
  • yw ... if it is helpful, you can upvote the helpful answers, and select one which you consider best to answer your question (and press accept).
    – Michel Keijzers
    Jan 15, 2018 at 19:28
0

case doesn't work like that; it can only switch on a single integer. Are you trying to pattern-match those sequences of bytes? You'll have to use some sort of state machine instead, keeping track of what bytes you've received and where in the expected pattern you are.

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2
  • Can you give me some hints? I am a newbie and i don't know much about Arduino. Thanks
    – Ali khan
    Jan 13, 2018 at 21:49
  • As mentioned it won't work. But also note you read a single byte, but your arrays have eleven items in them. You should probably read 11 bytes and use a comparison routine. (memcmp, etc.)
    – user29840
    Jan 14, 2018 at 7:23

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