# Homey Arduino variable names

**URL:** <https://community.homey.app/t/homey-arduino-variable-names/60719>\
**Category:** Questions & Help\
**Created:** [February 19, 2022, 10:08pm UTC](https://community.homey.app/t/homey-arduino-variable-names/60719 "2022-02-19T22:08:03Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![w00kiee](https://avatars.discourse-cdn.com/v4/letter/w/5fc32e/32.png) [@w00kiee](https://community.homey.app/u/w00kiee)\
**Post date:** [February 19, 2022, 10:08pm UTC](https://community.homey.app/t/homey-arduino-variable-names/60719/1 "2022-02-19T22:08:03Z")

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I’ve succesfully written an Arduino sketch that sends temperature, relative humidity and pressure data from an ESP32 + bme280 to my Homey Arduino App. After the DHT11 example I’ve named the vars like this:

```
Homey.setClass("sensor");
Homey.addCapability("measure_humidity");
Homey.addCapability("measure_temperature");
Homey.addCapability("measure_pressure"); (this one was a wild guess)

```

Without telling the Arduino anything, Homey decides that my humidity is probably relative humidity expressed in %, temperature is degrees Celcius and pressure is mbar/hpa. How does it know that and how do I name my other variables to get the same goodness with my other sensors? I have a CO2 (MHZ14a) and particle sensor (PMS5007). I have no idea how to name the variables.

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**Author:** ![JPe4619](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/jpe4619/32/9017_2.png) [@JPe4619](https://community.homey.app/u/JPe4619)\
**Post date:** [February 20, 2022, 1:27am UTC](https://community.homey.app/t/homey-arduino-variable-names/60719/2 "2022-02-20T01:27:16Z")

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> **[Tutorial: Device Capabilities - Homey Apps SDK v3](https://apps-sdk-v3.developer.homey.app/tutorial-device-capabilities.html)**

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<div class="post-metadata">

**Author:** ![w00kiee](https://avatars.discourse-cdn.com/v4/letter/w/5fc32e/32.png) [@w00kiee](https://community.homey.app/u/w00kiee)\
**Post date:** [February 20, 2022, 7:25am UTC](https://community.homey.app/t/homey-arduino-variable-names/60719/3 "2022-02-20T07:25:03Z")

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Thank you very much!

I see some things are not in there, but it’s a great starting point for me

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**Author:** ![Joolee](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/joolee/32/3064_2.png) [@Joolee](https://community.homey.app/u/Joolee)\
**Post date:** [March 10, 2022, 7:34pm UTC](https://community.homey.app/t/homey-arduino-variable-names/60719/4 "2022-03-10T19:34:28Z")

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Psst, might I suggest using ESP Easy? Disclaimer: App by me

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<div class="post-metadata">

**Author:** ![w00kiee](https://avatars.discourse-cdn.com/v4/letter/w/5fc32e/32.png) [@w00kiee](https://community.homey.app/u/w00kiee)\
**Post date:** [March 10, 2022, 8:12pm UTC](https://community.homey.app/t/homey-arduino-variable-names/60719/5 "2022-03-10T20:12:07Z")

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I will check it out!