I am trying to use I2C to communicate between my XBee3 (controller) and an adafruit trinket m0 (peripheral). I'm pretty confident I have the modules connected properly (trinket SCL/pin 2 to xbee SCL/pin DIO1 & trinket SDA/pin 0 to xbee SDA/pin DIO11, and both grounds are connected). Here is my arduino code on the trinket:

#include <Wire.h>

void setup()
Wire.begin(72); // join i2c bus
Wire.onReceive(receiveEvent); // register event
Serial.begin(9600); // start serial for output
Serial.print("Waiting for data...");

void loop()

// function that executes whenever data is received from master
// this function is registered as an event, see setup()
void receiveEvent(int howMany)
(void)howMany; // avoid compiler warning about unused parameter

while(1 < Wire.available()) // loop through all but the last
char c = Wire.read(); // receive byte as a character
Serial.print(c); // print the character
int x = Wire.read(); // receive byte as an integer
Serial.println(x); // print the integer

and here is my code on the XBee:

from machine import I2C

# Instantiate an I2C peripheral.
i2c = I2C(1)
slave_addr = 72
i2c.writeto(slave_addr, b'123', False)

Additionally, when I run an i2c.scan() on the xbee with an ISM330DHCX connected to the xbee's I2C, the address pops right up. But when I use the exact same code with the xbee connected to the trinket m0, the xbee cannot find any devices. (Code pasted below)

from machine import I2C

# Instantiate an I2C peripheral.
i2c = I2C(1)

# Scan for I2C slaves connected to the interface and print their address.
for address in i2c.scan():
    print("- I2C device found at address: %s" % hex(address))

Does anyone have any ideas what I'm doing wrong with configuring the trinket m0 to be an i2c peripheral? Thank you!

  • Did you solve this problem? I'm trying to communicate with I2C between two Trinket M0 and am facing the same issue. Aug 28 at 9:43
  • I never solved it. After some additional research, I figured that the trinket M0 couldn't be configured as a peripheral. I ended up using a different microcontroller. Aug 29 at 11:23

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