readBytesUntil() for String Data

Projects Programming
1

Using LoRa communication, string_buf of LoRa client has the following data.

string_buf has data: 23.5, 88, 1002, 12500

But when I compile my sketch, I got an error message like “ 'class String' has no member named 'readBytesUntil' “.
I know that the readBytesUntil function cannot be used because the string_buf of my sketch is not a Stream Class.
I studied the Stream class in the Arduino reference (Stream - Arduino Reference), but I couldn't figure out how to make the string data as a Stream class.

How do I modify my sketch to use the ”readBytesUntil(',', myData[0],20)” function?

#include <RH_RF95.h>
#include <Stream.h>

#define RFM95_INT     18  // "A"  // MEGA 18, UNO 2
#define RFM95_CS      53  // "B" // MEGA 53, UNO 10 
#define RFM95_RST     40  // "C"  // MEGA assigned 40(임의로 변경 가능), uno 9(Module의 reset pin과 연결)
#define RF95_FREQ 915.0

RH_RF95 rf95(RFM95_CS, RFM95_INT);

int LED = 9;
int i = 0;
char myData[4][20] = {0};
char string_buf[4][5] = {0};

void setup() {

  Serial.begin(9600);
  while (!Serial) {
    // while (!Serial) ; // Wait for serial port to be available
    delay(1);
  }
  delay(100);
  Serial.println("RX Serial ok");

  if (!rf95.init())
    Serial.println("rf95_RX init failed");
  else
    Serial.println("rf95_RX init OK");
  //   rf95_serial.begin(9600);
  //   Serial.println(rf95_serial.available());

}

void loop() {
  Serial.println("Receiving Data from Server");
  char buf[RH_RF95_MAX_MESSAGE_LEN];
  //uint8_t buf[RH_RF95_MAX_MESSAGE_LEN];
  uint8_t len = sizeof(buf);
  String buf_String[RH_RF95_MAX_MESSAGE_LEN];

  if (rf95.waitAvailableTimeout(4000))
  {
    // Should be a reply message for us now
    if (rf95.recv(buf, &len))// buf has "23.5,88,1002,12500"received from RF95_TX;

    {
      RH_RF95::printBuffer("printBuffer_buf_Data,buf,len: ", buf, len);
      Serial.print("(char*)buf: ");
      Serial.println((char*)buf);
      String string_buf = (char*)buf;
      Serial.print("String string_buf=(char*)buf: ");
      Serial.println(string_buf);
      // string_buf has data : "23.5,88,1002,12500"

      string_buf.readBytesUntil(',', myData[0], 20);

      {
        float X1 = atof(myData[0]);
        //Serial.println(X1,1);
        //int X2 = atoi(myData[1]);
        //Serial.println(X2);
        //int X3 = atoi(myData[2]);
        //Serial.println(X3);
        //int X4 = atoi(myData[3]);
        //Serial.println(X4);

        digitalWrite(LED, HIGH);
        Serial.print("RSSI: ");
        Serial.println(rf95.lastRssi(), DEC);
      }
      delay(100);
    }
    else
    {
      Serial.println("recv failed");
    }
  }
  else
  {
    Serial.println("No reply, is rf95_server running?");
  }
  delay(400);
}

image

2

Look at readStringUntil()

5

@juspark, in future, please post your code inline instead of as an attachment. You will reach a bigger audience. I've done it for you this time.

#include<SoftwareSerial.h>
#include <RH_RF95.h>
#include <Stream.h>

#define RFM95_INT     18  // "A"  // MEGA 18, UNO 2
#define RFM95_CS      53  // "B" // MEGA 53, UNO 10 
#define RFM95_RST     40  // "C"  // MEGA assigned 40(임의로 변경 가능), uno 9(Module의 reset pin과 연결)
#define RF95_FREQ 915.0

RH_RF95 rf95(RFM95_CS, RFM95_INT);

//SoftwareSerial rf95_serial(50,51);//(RX,TX)MISO(Master In Slave Out) pin50=RX, MOSI(Master Out Slave In) pin51=TX
//uint8_t myData[]="23.5,88,1002,12500,";
int LED = 9;
int i=0;
char myData[4][20]={0};
char string_buf[4][5]={0};

void setup() {
//String inString ="";
 
 Serial.begin(9600);
 while (!Serial) {
   // while (!Serial) ; // Wait for serial port to be available 
    delay(1);
  }
  delay(100);
  Serial.println("RX Serial ok");
 
if (!rf95.init())
    Serial.println("rf95_RX init failed");
  else
    Serial.println("rf95_RX init OK");
 //   rf95_serial.begin(9600);
 //   Serial.println(rf95_serial.available());
    
}

void loop() {
 Serial.println("Receiving Data from Server");
 char buf[RH_RF95_MAX_MESSAGE_LEN];
 //uint8_t buf[RH_RF95_MAX_MESSAGE_LEN];
 uint8_t len = sizeof(buf);
 String buf_String[RH_RF95_MAX_MESSAGE_LEN];
 
 //String inString ="";
 
  if (rf95.waitAvailableTimeout(4000))
  { 
    // Should be a reply message for us now 
    if (rf95.recv(buf, &len))// buf has "23.5,88,1002,12500"received from RF95_TX;
     
     {
     RH_RF95::printBuffer("printBuffer_buf_Data,buf,len: ", buf, len);
     Serial.print("(char*)buf: ");     
     Serial.println((char*)buf);
     String string_buf = (char*)buf;
     Serial.print("String string_buf=(char*)buf: ");
     Serial.println(string_buf);
     // String string_buf has data String: "23.5,88,1002,12500" 
     
     string_buf.readBytesUntil(',',myData[0],20);
     
     {
     float X1= atof(myData[0]);
     //Serial.println(X1,1);
     //int X2 = atoi(myData[1]);
     //Serial.println(X2);
     //int X3 = atoi(myData[2]);
     //Serial.println(X3);
     //int X4 = atoi(myData[3]);
     //Serial.println(X4);
     
     digitalWrite(LED, HIGH);
     Serial.print("RSSI: ");
     Serial.println(rf95.lastRssi(), DEC);    
    }
    delay(100);
    }
    else
    {
      Serial.println("recv failed");
    }
  }
  else
  {
    Serial.println("No reply, is rf95_server running?");
  }
  delay(400);
}
6

Thank You

7

It is easier to use the String functions than to make a String into a Stream and using the Stream functions.

   int commaIndex = string_buf.indexOf(',');

  if (commaIndex != -1)
  {
    myData[0] = string_buf.substring(0, commaIndex);
  }
8

To: johnwasser
Thank you very much.
Editing my sketch as you recommended, I have solved the problem I had been struggling with it for about 2 weeks.
A part of the modified code is like the capture picture below.

image
image842×423 22.4 KB

9

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