Library that needs I2C pins defined

I am using a Davis Vantage Pro2 weather station sensor - Temp and Humidity

It is an SHT31-LS and the generic SHT libraries don’t work - it uses a Legacy Sensibus single shot output

I have had success with other boards using I2C where I can define the pins for the library - for the Wisblock, using the I2C on the base board I have been trying 19 - SDA and 20 - SCL

 * ReadSHT31LS
 * Read temperature and humidity values from an SHT31-LS 
 * May also work with the SHT1x series (SHT10, SHT11, SHT15) sensors.
 * Copyright 2016 Alan Marchiori [email protected]

#include <sensirion.h>

// Specify data and clock connections and instantiate sensirion object
#define dataPin  19
#define clockPin 20
#define ledPin 13

sensirion sht(dataPin, clockPin);

void setup()
   Serial.begin(9600); // Open serial connection to report values to host
   Serial.println("Starting up");
   pinMode(ledPin, OUTPUT);

void loop()
  float temp_c;
  float temp_f;
  float humidity;

  // blink
  digitalWrite(ledPin, (digitalRead(ledPin) == HIGH) ^ 1);

  if (1){
    uint16_t status = sht.readStatus();
    Serial.print("Status: 0x"); Serial.println(status, HEX);

  if (1){
    humidity = sht.readHumidity();
    Serial.print("Humidity: "); Serial.print(humidity); Serial.println("%");

  if (1){
    temp_c = sht.readTemperatureC(); 
    Serial.print("Temperature: "); Serial.print(temp_c, DEC); Serial.println(" C");
  if (1){
    temp_f = sht.readTemperatureF(); 
    Serial.print("Temperature: "); Serial.print(temp_f, DEC); Serial.println(" F");

Is there anything else I could be trying?

thanks in advance

Hello @mutton, Welcome to the forum.

I2C on the RAK5005-O is connected to GPIO 13 (SDA) and GPIO 14 (SCL), not 19 and 20. 19 and 20 are the pin numbers on the connector, not the GPIO numbers.

Thanks but I already tried 13 and 14 as well after reading through the documentation - in the code can I just use those numbers or is it something like GPIO13?

Got it working - needed some external pullup resistors

Are internal pullups available on those pins 13 and 14?

edit: Answering my own question - yes they are

The RAK5005-O has pullups on the I2C lines:
But might not be enough for the SHT31-LS.

But glad you got it to work. Was fighting with these SHT31 long time ago on an ESP32. I prefer the sensors with a “real” I2C interface.