Split string received from Terminal

Need Help With My Project
1

My question is very much inline with this post, however I have a more direct need to be able to split the string received from the Terminal control.

The Terminal control offers me a non-graphical means of controlling devices without the need of cluttering my display with various controls e.g. Buttons, Sliders, Menu’s, etc.

This is what I am trying to achieve:
Use the Terminal to send a string, e.g:

  • R1:ON // set Relay1 to 1
  • L3:5 // turn Light3 on for 5min (1000 * 60 * 5)

The Arduino Sketch will receive the following string through param.asStr() :
R1:ON

In the Sketch I need to split the received string on the delimiter “:”… and this is where I have difficulty getting things to work.
(Please note that my knowledge and experience with C/C++ is very limited - non-existing actually)

I have tried strtok() but have difficulty in getting the string passed into a char array. I also don’t know if the string passed conforms to a C-string ended with “/0”. I’ve tried to test this with SizeOf() but I get an error. I’ve also tried both param.asStr() and param.getBuffer(), all failed. Also tried .toCharArray which also failed with data type conversion.

Unfortunately, most (90%) of the research I’ve done is focussed on the Serial.Read(). I’ve tried to implement the same logic they use there, but things go askew the moment I try to convert the received string to a char array.

Any suggestion would greatly be appreciated.

Regards,
T

2

See my snippet of a working copy that does string manipulation etx…

 BLYNK_WRITE(V14)
  {
  /// take "commands" from the terminal and acting accordingly ///
  /// https://www.arduino.cc/en/Tutorial/StringSubstring ///
  /// (stringOne.equalsIgnoreCase(stringTwo)) ///
  /// stringOne.trim(); ///
  /// int strgLenght = param.getLength(); /// get the string lenght ///
  String getString = param.asStr(); /// get the string ///
  getString.trim(); /// cut off the blank spece(s) at the end of the string ///
    if (getString.equalsIgnoreCase("timer1")) {
      timer1PrintOut();
      return;
    } else if ( getString.startsWith("onrl1") || getString.startsWith("onrl2") ) { /// format onrl1,30 or onrl2,34 ...
    int firstCommaIndex = getString.indexOf(',');
    relaySelection = getString.substring(0, firstCommaIndex);
    String durationToOn = getString.substring(firstCommaIndex+1);
    duration = durationToOn.toInt();
     
     ///terminal.printf("duration(in seconds)=%d\n", duration);
     ///terminal.flush();
     /// make a now() start with now()+duration stop at Timer1 if RL1 or Timer2 if RL2 ... ///
     manualEndTime = now()+ (duration - 1); /// this is the manualEndTime that manualActiveRLTimer will check each 2 seconds for RLn-OFF
     /// this need other commant from time library ... /// int2Time(manualEndTime);
     /// activate rl1 or rl2 and then call manualActiveRLTimer to take care the RL-OFF state   
     ///terminal.printf("The Relay:%s, Will be ON for %s seconds\n",relaySelection, durationToOn);
     terminal.println(); terminal.print(relaySelection+"  Duration="); 
     int2Time(duration);
     terminal.printf("  end @ %02d:%02d:%02d \n",hour(manualEndTime), minute(manualEndTime), second(manualEndTime));
     terminal.flush();
        
          if(relaySelection == "onrl1") { /// RL1 activation ///
            digitalWrite(RL1,HIGH);
            Blynk.virtualWrite(V16, HIGH);
            Blynk.setProperty(V16, "color", RED);
          } else if(relaySelection == "onrl2") { /// RL2 activation ///
            digitalWrite(RL2,HIGH);
            Blynk.virtualWrite(V17, HIGH);
            Blynk.setProperty(V17, "color", RED);
            }
     timer.enable(manualActiveRLTimer);
     return;
    } else if (getString.equalsIgnoreCase("restart")) {
    terminal.println("OK I do restart !");
    terminal.flush();
    yield(); yield(); delay(500);
    ESP.restart();
    } else if (getString.equalsIgnoreCase("?") || getString.equalsIgnoreCase("help")) {
    terminal.println("The regognised commands are: ");
    terminal.println("onrl1,nn, onrl2,nn, timer1(-4), sync, BDC, BDC0, fhon, fhoff, clear/cls, tson, tsoff, ts?, startled, stopled, tz?, tz2, tz3, diags, restart, cnv nnnn");
    terminal.flush();
    return;
    } else {
    // Send it back
    terminal.print("You said:");
    terminal.write(param.getBuffer(), param.getLength());
    terminal.println();
    terminal.println("Type ? or help to get help...");
    terminal.println();
  }
  // Ensure everything is sent
  terminal.flush();
}
/// END of V14 terminal processing function ///

If you need further help, don’t hesitate to ask me.

Thanks and Best Regards,
Mike Kranidis

3

Hi Mike,

Thanks for the reply and your sketch. Interestingly enough, I looked at one of your posts, posted back in 2016 I think it was. Although, this sketch looks much better than your original sketch ;).

I will definitely look jump into your sketch and follow your logic.
Is there any additional references to libraries I need to make in my sketch ?

Regards,
Tino

4

no, it is using the very standard build-in infrastructure of the ESP8266 Arduino Core 2.4.0-rc2 ( I strongly suggest to get the latest one, that is 2.4.0-rc2 )

Tell me your opinion after implemented this to your sketch.

Best Regards,
Mike Kranidis

5

Thanks for the reply, Mike.

I scanned through your sketch (not implemented yet) and just love what you did with the various number of commands you are pushing through. That is exactly what I have in mind and I am glad I decided to post my request for help… but not as glad as I am that you posted. Your post is the cherry on top.

Once I have converted your sketch and implemented on my nodeMCU, I will let you know what I think and how well it functions :wink:

Regards,
Tino

1 Like
6

But it’s still the same principle :wink: Looking at my own functions for parsing data (check my post about RF 433…) I think something like this will split the string for you:

    char tempChars[] = param.asStr(); // R1:ON 

	char * strtokIndx;  // This is used by strtok() as an index

	strtokIndx = strtok(tempChars,":");
	strcpy(myDevice, strtokIndx); // myDevice = R1

	strtokIndx = strtok(NULL, ":");
	strcpy(myCommand, strtokIndx);  // myCommand = ON

My code relies heavily on this excellent write up which explains the parse/splitting very well: Serial Input Basics - updated

7

See also this fine example:

8

Thank you for your reply and attached information. I also looked at both the Serial Input Basics and Serial Input Basics - updated links. However, I could not get anything to work. I will definitely play around with your code as to allow me versatility in logic methods.

9

Perfecto!! It seems to work now with your sketch example. Thank you for chpping in help here Mike, much appreciated.

I am not entirely sure but I think I know what happened:
What I did differently, and I am not sure if this is the reason, is I used a function to process the data received from the Terminal control, e.g.:

// Wait for input from Terminal
BLYNK_WRITE(V14) {

getTermData( param.asStr());
}

void getTermData(String termData) {
// process data here
}

In my mind there should not be any reason that the data type changed from the BLINK_WRITE function to the getTermData() function, however, I was getting all kinds of weird data type conversion errors.

Regards,
Tino

10

I’m not sure if I understand you… But variables declared in a function doesn’t get passed to another function unless you declare them as global.

https://www.arduino.cc/en/Reference/Scope

11

My apologies, wrong terminology. I should rather have said a “value” instead of a variable. I was referring to passing a value (derived from the variable param.asStr) to a function.

Regards,
T

12

Yes, but you assign values to a variable, which is then passed.

EDIT : It seems like I’ve been contributing to the confusion with a beginner’s mistake - Mixing up String with string. :roll_eyes: For that I’m sorry!

So I had to check how String works and this example works “as is”. Hopefully it will also work with param.asStr() in a BLYNK-function.

String myDevice; // Global
String myCommand;

void setup() {
  Serial.begin(115200);
}

void stringTest() {

  byte part1;
  byte part2;

  String getString = ("R1:ON");
  //String getString = param.asStr();

  part1 = getString.indexOf(':');
  myDevice = getString.substring(0, part1);
  part2 = getString.indexOf(':', part1 + 1 );
  myCommand = getString.substring(part2);

  Serial.print("The String is: ");
  Serial.println(getString);

  termData();
}

void termData() {

  if (myDevice == "R1") {
    if (myCommand ="ON") {
      Serial.println("Turning ON relay 1");
    }
    else {
      Serial.println("Turning OFF relay 1");
    }
  }
  
  Serial.print("Device is: ");
  Serial.println(myDevice);  
  Serial.print("Command is: ");
  Serial.println(myCommand);

}

void loop() {
  stringTest();
  delay(5000);
}
13

No worries :slight_smile: I still don’t know the difference between ‘string’ and ‘String’, except that most people advise not to use ‘String’ in a microcontroller environment… something to do with memory usage.

I’d like to look at your code as well. Less cluttered the way you presented it. Thanks for that.

Regards,
T