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.


The slave code is as follows:

#include <Wire.h>

void setup() {

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

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

// 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() {
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--; //reset the last increment
  if (printNow){
        Serial.println("Master sent this text: ");

  // Write a value over I2C to the slave
  Wire.write(txt, (i-1) ); // not sending the terminating 0


1 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.

  • 2
    you posted an answer to the question here ... it is no place to be asking further questions
    – jsotola
    Sep 6, 2022 at 16:46
  • What jsotola means is if you have a new question, ask a new question. You may include a link to this question if you think it is relevant. Please take the tour to understand better how the site works.
    – goldilocks
    Oct 6, 2022 at 19:29

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