Dasduino CONNECTPLUS I2C scan finds no devices after reconnection

TECHNICAL SUPPORT NULA Development Boards
1

Customer:

I built an easyC ecosystem with an SHTC3 temperature sensor, a 2 channel easyC relay, an easyC hub, all connected to a Dasduino CONNECTPLUS. The system worked as a thermostat controlled by the temperature sensor readings. When I reconnected the setup to my computer a day later, it stopped working. I tried different easyC cables and connected each component separately, but nothing works. The easyC pins look intact on the sensor, relay, and board, and the relay lights up when connected, showing power is reaching it. Running the Soldered I2C scan program returns “no I2C devices found”.

Originally submitted via email support on 14 June 2025. Migrated to the forum for community visibility.

2

Soldered Support:

Since you’re seeing “no I2C devices found” even though the relay powers on and the easyC connections appear intact, here are some potential causes and steps to check:

  1. Power Supply and Voltage
  • Ensure the Dasduino CONNECTPLUS is delivering stable 3.3V or 5V to the sensor and relay modules.
  • The SHTC3 is sensitive to supply voltage fluctuations and may not respond if undervolted.
  1. Cable Orientation and Damage
  • Inspect for bent or pushed-in pins on the easyC connectors at both ends. Internal cable breaks can occur. Try a single cable in isolation with basic software examples for one module to verify the cable and module work, then incrementally add components.
  1. SHTC3 Sensor Behavior
  • The SHTC3 has a sleep mode by default and requires a wake-up command after power-up before it responds over I2C.
  • If your sketch doesn’t send the wake-up command during a new upload, the sensor may appear unresponsive.
  1. I2C Bus Recovery
  • I2C devices can get stuck in a busy state. Try power-cycling the entire setup including the Dasduino board.
  • Disconnect all easyC devices and reconnect them one by one, running the I2C scan after each connection.
  1. Firmware or Sketch Issues
  • Double-check that the code loaded on the Dasduino includes proper I2C initialization.
  • Re-upload your previously working sketch, or try all the basic examples from each peripheral’s library.

If the issue persists after checking all of the above, provide the exact code you’re using, a photo of your physical setup, and the output of the I2C scan sketch with everything connected.