I'm new here, so I hope my question is not naive. I'm using Arduino mega connected with a pulse sensor and a GPS (and other things that are not related to our problem), pulse sensor and GPS data are sent momentarily through HC-12 433 Mhz module to a receiver arduino uno that is only receiving data through HC-12 as well

for processing reasons, I send GPS data with a "G" prefix .. e.g "G11.00,7.45". and pulse data consist of those three: "S100" "Q97" "B22" // 100,97,22 are just examples, and each one is sent alone

for some reason, the receiver Arduino uno, is reading the data in it's ASCII decimal form and also separate it in a new line.

I can not use Serial.readString(), because it only print data after terminating the Serial communication and I need it momentarily, I tried to configure Serial.setTimeout() , but I couldn't manage to find a suitable time for all data.

please check my code and help me solve my problem, thank you

#include <Adafruit_GPS.h>
// what's the name of the hardware serial port?
#define GPSSerial Serial1
// Connect to the GPS on the hardware port
Adafruit_GPS GPS(&GPSSerial);

String gpsData="";
String pulseData="";
#include <SoftwareSerial.h>
SoftwareSerial mySerial(12, 13); // RX, TX  HC-12
uint32_t timer = millis();
void setup(){  // I think there is no problem here
  interruptSetup();   // initialize timers to read pulse sensor and GPS at fixed intervals
void loop(){
 // that show me if there is a new data, you can skip it
 if (GPS.newNMEAreceived()) {
    // we end up not listening and catching other sentences!
    // so be very wary if using OUTPUT_ALLDATA and trying to print out data
    GPS.lastNMEA(); // this also sets the newNMEAreceived() flag to false

if (millis() - timer > 10000) { // send GPS data every 10 seconds
    timer = millis(); // reset the timer
    if (GPS.fix) {
      gpsData.concat(x);  // I also tried String(x)
      gpsData.concat(y);  // I also tried String(y)
      mySerial.println(gpsData);  // here I send GPS  data through HC-12 to the receiver Arduino uno
      gpsData=""; // reset 

void sendDataToProcessing(char symbol, int data ){
 // here I send pulse data through HC-12 to the receiver Arduino uno, and then process it using processing in the receiver arduino
    Serial.println(pulseData);  // just for debugging and it was okay 
    pulseData=""; //reset

interruptSetup() {
// no need to read it, it is just some timer 1 and timer 2 initialization and their ISR, timer 1 read pulse sensor every 2 milliseconds (yeah fast but I guess mega could handle it),and do some calculations to find S, Q, and B.
and timer 2 read GPS coming sentences.

the receiver code

void setup() {
  // put your setup code here, to run once:
Serial.begin(115200);  //I will connect HC-12 directly to pin 0,1

void loop() {
  // put your main code here, to run repeatedly:
while(Serial.available() >1){
  String input = String (Serial.read());//read string , I need to cast it into String because data comes in ASCII
// I also tried int input = Serial.read() ; //same thing happened

waiting for your response.

###edit### to conclude the problem is that I want to receive data in the uno as it has been sent from the mega

e.g: I receive sI guess the ascii of the letter and the number also changes to some number

send  |  recive
S490  | 52
Q252  | 10
B160  | 48

I used Serial.write(Serial.read()) instead of Serial.println, and it worked, does someone know why?

  • 1
    It's hard for me to understand what your problem is, but I think changing Serial.println(input); to Serial.print(input); will remove the added newlines (if that was the problem). – Gerben Aug 14 '20 at 8:50
  • I tried to restate the problem, check it again please – Aidakf Aug 14 '20 at 9:03
  • I think, using char input = Serial.read(); would have worked in your old code. Serial.read returns and int with the character/ascii code (or -1 if it gets a read-error). Serial.print doesn't know it's ascii and will interpret it as a integer, and will convert this number to the Ascii representation of that number. Apparently String(...) does the same. Write doesn't try to be clever, and just reads a byte, an sends this byte out over serial. Is your problem solved now? – Gerben Aug 14 '20 at 9:45
  • No, it is now printing the same output but each char is in a new line, for example like this : ``` B 1 2``` – Aidakf Aug 15 '20 at 7:35
  • 1
    oh yeah it worked, I didn't notice, thank you ....... – Aidakf Aug 15 '20 at 15:00

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