Program to test i2c communication with serial prints breaks RP pico

Question

Background: I am trying to test the communication of 2 raspberry pi pico using i2c. Firstly, i sent a string from one and receive it from the second one. Both of them print the results in the serial monitor. I am planning to use 2 usb cables and open 2 serials to see the results. I am writing in the Arduino IDE using the Arduino-pico core.

However, when i upload a sketch, the raspberry pi disappears from my computer. If i plug it out and then plug it it, the computer doesn't recognize it. I have to reset it.

Question: I want to understand why this happens to find a work-around and avoid the same problem in the future.

Programms:

The slave code is as follows:

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  while(!Serial)
  
  Wire1.setSDA(4);
  Wire1.setSCL(5);
  Wire1.begin(0x30);
  Wire1.onReceive(recv);
}

static char buff[100];
static int printNow =0;

void loop() {
  if (printNow){
  Serial.println("Slave Received : ");
  Serial.println(buff);
  printNow= 0;
  }
  
  delay(1);
}

// These are called in an **INTERRUPT CONTEXT** which means NO serial port
// access (i.e. Serial.print is illegal) and no memory allocations, etc.

//// Called when the I2C slave gets written to
void recv(int len) {
  int i;
  // Just stuff the sent bytes into a global the main routine can pick up and use
  for (i = 0; i < len; i++) {
    buff[i] = Wire1.read();
  }
  buff[i] = 0;
  printNow = 1;
}

The master code is as follows:

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  while(!Serial)
  
  Wire.setSDA(4);
  Wire.setSCL(5);
  Wire.begin();
  
}
static int buff[100];

void loop() {
  int i = 0;
  char txt[50];
  int printNow = 0;

  while(Serial.available() ){
    txt[i] = Serial.read(); //int
    if ( txt[i] == '\n' ){
      printNow = 1;
      txt[i] = '\0';
    }
    i++;
  }
  i--; //reset the last increment
  if (printNow){
        Serial.println("Master sent this text: ");
        Serial.println(txt);
  }

  // Write a value over I2C to the slave
  Serial.println("Sending...");
  Wire.beginTransmission(0x30);
  Wire.write(txt, (i-1) ); // not sending the terminating 0
  Wire.endTransmission();

} 

Answer 1

So i found out that the problem was because i was trying to use Wire1 on pins that do not support wire1. If you see the pinout, GP4,GP5 are for i2c0, that means Wire and not Wire1.

I didn't expect that this coding error would get the rp stuck. I would appreciate if somebody could explain why.