Just a simple echo program using Arduino

rhee.ino

#include <Arduino.h>

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
  readFuncInputVoltage();
}

void readFuncInputVoltage() {
  char* input = NULL;
  int size = 0;
  char c = 0;
  while(true) {
    if(!Serial.available()) continue; 
    c = Serial.read();
    ++size;
    input = realloc(input, size);
    if(c == '\n') {
      input[size - 1] = '\0';
      Serial.println(input);
      return;
    } else {
      input[size - 1] = c; 
    }
  }
  free(input);
}