UNO R4 WiFi + Modulino Thermo / Pixels – No I²C device detected (Wire or Wire1)

Official Hardware Kits Plug and Make Kit
1

Hello everyone,

I'm trying to use the Arduino Plug and Make Kit with an Arduino UNO R4 WiFi , but I cannot get any of the Modulino devices to be detected on I²C.

I started with the Modulino Thermo example from the official documentation:

https://docs.arduino.cc/tutorials/modulino-thermo/how-general/

The sketch uploads correctly, but the readings are always:

Temperature (C) is: 0.00
Temperature (F) is: 32.00
Humidity (rH) is: 0.00

When I modified the sketch to check initialization, I get:

thermo.begin() = FAILED

What I tested

1. Qwiic connection (as intended for Modulino)
UNO R4 WiFi → Qwiic cable → Modulino Thermo

I ran an I²C scanner on Wire1 (since Qwiic uses Wire1 on UNO R4 WiFi).

Result:

No I2C devices found on Wire1

2. Manual wiring using the Modulino solder header

To rule out a bad Qwiic cable/connector, I wired the Thermo module manually:

Modulino GND → UNO GND
Modulino 3.3V → UNO 3.3V
Modulino SDA → UNO SDA
Modulino SCL → UNO SCL

Then I ran a standard Wire I²C scanner .

Result:

No I2C devices found on Wire

3. Tried another Modulino

I also tested the Modulino Pixels module with both connection methods.

Same result:

No I2C devices found

Summary

  • Board: Arduino UNO R4 WiFi
  • Kit: Arduino Plug and Make Kit
  • Modules tested: Modulino Thermo and Modulino Pixels
  • Tested both:
    • Qwiic connector (Wire1 )
    • Manual wiring via header (Wire )
  • Both I²C scanners detect no devices at all

Question

At this point I'm wondering:

  • Is there something special required to enable the I²C bus on the UNO R4 WiFi when using Modulino?
  • Could this indicate a faulty board or Qwiic interface?
  • Is there any recommended diagnostic step for the Plug and Make Kit hardware?

Any suggestions would be greatly appreciated.

Thanks!

2

You are using pull up resistors on the I2C lines to 3v3 are you?

What value are these?