#include "Adafruit_HTU21DF.h" Adafruit_HTU21DF htu = Adafruit_HTU21DF(); struct { char temperature[15] = {0}; char humity[15] = {0}; } htuData; void init_HTU21(){ if (!htu.begin()) { Serial.println("Couldn't find sensor HUT21D!"); while (1); } Serial.println("HUT21D gefunden"); } void read_HTU21D() { float t = htu.readTemperature(); dtostrf(t,10,4,htuData.temperature); float h = htu.readHumidity(); dtostrf(h,8,2,htuData.humity); } void M2M_HTU21D(long deviceId = 4711) { char topic[100]; sprintf(topic, "%s%ld%s", "hjk/devices/", deviceId, "/telemetry/temperature_Htu_21" ); client.publish(topic, htuData.temperature, true); sprintf(topic, "%s%ld%s", "hjk/devices/", deviceId, "/telemetry/humity" ); client.publish(topic, htuData.humity, true); Serial.printf("HTU21:\t\t %s °C\n", htuData.temperature); Serial.printf("HTU21:\t\t %s %% \n", htuData.humity);