Read Serial Input into Char Array

Question

So i've managed to wire up an ESP-01 module to my arduino, now im attempting to parse the +IPD responses the chip gives over a serial connection. Im not really all that handy with C++ but this is what i've managed to come up with after researching a bunch online:

#include <SoftwareSerial.h>
SoftwareSerial ESP8266(2, 3); // RX | TX
int baud = 9600;


void setup() {
  ESP8266.begin(baud);
  Serial.begin(baud);
  Serial.println("--- Start ---");
  
}

void loop() {

  if (ESP8266.available()) // check if the esp is sending a message
  {
    Serial.println("Something received");
    delay(500);
    if (ESP8266.find("%<"))
    {
      Serial.println("--------------- DEBUG ----------------A");
      char temp = {char(ESP8266.read())};
      while ((temp != '%') && (ESP8266.available())) {
        Serial.print(temp);
        temp = char(ESP8266.read());
      }
      Serial.println("\n--------------- END DEBUG ----------------");
    }
  }
}

The standard response the chip gives when receiving a message is as follows:

+IPD,<len>:<Message>
+IPD,0,14:%<255,128,0%

The data im trying to send - random RGB values (using '%<' and '%' as flags/markers):

%<255,128,0%

From here, i've managed to write the above code, which will print out the following over serial:

So i've managed to get it to print the values i need over Serial, but i cant seem to store them in an array of some sort to do things with the data.

Things i've tried:

• using readString() instead of read(), coupled with indexOf to search/extract the data
• Looping and appending to a char array
• A bunch of array stuff, seems tricky though because you have to know the length when you declare it

Ideally, i'd like a function that reads the +IPD value, extracts the RGB data and then splits it into a 3 index array, like so:

rgbArray = {124, 234, 96};

Any and all help is super appreciated!

Answer 1

To store the input to an array, just allocate an array and store the data there.

      Serial.println("--------------- DEBUG ----------------A");
      int receivedLength = 0;
      char data[16];
      char temp = ESP8266.available();
      while ((temp != '%') && (ESP8266.available())) {
        Serial.print(temp);
        if (receivedLength < 16) data[receivedLength++] = temp;
      }
      for (int i = 0; i < receivedLength; i++) Serial.print(data[i]);
      Serial.println("\n--------------- END DEBUG ----------------");

Alternatively, you can do conversion to integers while reading like this:

      Serial.println("--------------- DEBUG ----------------A");
      int rgbSize = 0;
      int rgbArray[3];
      int currentValue = 0;
      char temp = ESP8266.available();
      while ((temp != '%') && (ESP8266.available())) {
        Serial.print(temp);
        if (temp == ',') {
          if (rgbSize < 3) rgbArray[rgbSize++] = currentValue;
          currentValue = 0;
        } else {
          currentValue = currentValue * 10 + (temp - '0');
        }
      }
      if (rgbSize < 3) rgbArray[rgbSize++] = currentValue;
      for (int i = 0; i < rgbSize; i++) {
        if (i > 0) Serial.print(',');
        Serial.print(rgbArray[i]);
      }
      Serial.println("\n--------------- END DEBUG ----------------");

Answer 2

Ended up going with a different way of doing things:

Managed to read about readStringUntil(''); in some dark corner of the web. So i came up with a super dirty implementation - but it works:

Assume your input string is:

+IPD,0,14:%<255,128,0%

Then do:

if (ESP8266.available()) // check if the esp is sending a message
  {

    delay(500);
    if (ESP8266.find("%<"))
    {
      r = ESP8266.readStringUntil(',');
      g = ESP8266.readStringUntil(',');
      b = ESP8266.readStringUntil('%');
    }
  }