Arduino restarts after serial input from Raspberry Pi - c++

Question

I have this code running on the arduino:
#include <SoftwareSerial.h>
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// pins!!!!
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
const int delayTime=10;
const int pin_yes_gate=3;
const int pin_no_gate=5;
int switchVal =0;
void setup()
{
Serial.begin(9600); // Initialize serial port to send and receive at 9600 baud
pinMode(pin_yes_gate, OUTPUT);
pinMode(pin_no_gate, OUTPUT);
}
void loop()
{
if (switchVal ==1 ){
allow();
}else{
prohibit();
}
if ( Serial.available())
{
String string = Serial.readString();
string.trim();
Serial.print("I received: ");
Serial.print(string);
Serial.print("\n");
if(string.equals("allowed"))
{
switchVal=1;
}else if(string.equals("error"))
{
switchVal=0;
}
}
}
void allow(){
digitalWrite(pin_yes_gate,HIGH);
digitalWrite(pin_no_gate,LOW);
delay(delayTime);
}
void prohibit(){
digitalWrite(pin_yes_gate,LOW);
digitalWrite(pin_no_gate,HIGH);
delay(delayTime);
}
and I'm writing echo allowed >> /dev/ttyACM0 which gives the reaction, but for less than a second, and then the arduino returns to the initial state. This is weird, as it works with the arduino IDE perfectly.
Am I missing something ?

Answer 1

Just solved it, apparently the problem is the
Serial.print("I received: ");
Serial.print(string);
Serial.print("\n");
It errors out if serial is not read. So either removing this, or as in my case I can't change anything on the arduino side run this command on raspi boot tail -f /dev/ttyACM0 & which opens a read port