Unable to find/connect I2C devices (SHT31 & SGP30)

Question

I have recently purchased an Arduino Nano 33 IOT together with two sensors:

• Adafruit SHT31-D (https://learn.adafruit.com/adafruit-sht31-d-temperature-and-humidity-sensor-breakout)
• Adafruit SGP30 (https://learn.adafruit.com/adafruit-sgp30-gas-tvoc-eco2-mox-sensor/)

However, so far I have not succeeded in reaching any of these two sensors. For example I connect the SHT31 sensor like this:

• +3.3V to Vin
• GND to GND
• A4 to SDA
• A5 to SCL

I have tried the default Adafruit SHT31-D example without success, the program appears to hang. I have tried a standard I2C scanner but it does not find any devices with the sensor connected. When the sensor is disconnected, it does find two devices (the IMU and something else I guess).

I believe there is something funky going on with the I2C connection of the internal sensors and the external ones but I have no idea how to troubleshoot this issue. I read some stuff about TwoWire (extern TwoWire Wire1; after the #include) but I am having a hard time figuring out if this is what I need and how to implement it.

I found these topics myself:

https://forum.arduino.cc/index.php?topic=639188.0

https://forum.arduino.cc/index.php?topic=658967.0

edit: I haven't had success dealing with these issues so far and I am still looking for some help with my problems!

Answer 1

one can code an I2C sensor (I'm using a SHT31) using custom GPIO ports like so:

//I2C Bus Pins
#define SDA 8
#define SCL 9

#include "Adafruit_SHT31.h"
TwoWire I2Cbus = TwoWire(0);
Adafruit_SHT31 sht31 = Adafruit_SHT31(&I2Cbus);

void setup(){
  Serial.begin(115200);            // USB communication with Serial Monitor
  Serial.print("Starting serial...");

  Serial.print("Starting SHT31...");
  startSHT(); 
}

 // ********************************************************
 void startSHT(){
  I2Cbus.begin(SDA, SCL, 100000ul); 
  if (! sht31.begin(0x44)) { // Set to 0x45 for alternate i2c addr
     Serial.println("Couldn't find SHT31");
while (1) 
delay(1);
  }
}