officeAir - A temperature and Humidity Meter and Google Sheet Logger with Raspberry Pi / ESP32 and I2C sensors

This project lets you log temperature and humidity data via Raspberry Pi and a sensor easily and automated way into you google sheet, collecting the raw data and automatically drawing a nice chart as data coming in. (The name and use case comes from life: initially we set this up to monitor DecentLabs office climate in a hot summer period, when air conditioning had some weakness.)

Code by: Róbert Szalóki, Hardware configuration and manual by: Zoltan Dóczi (RFsparkling), Licensed by DecentLabs

First lets see the Google sheet and its script side to prepare that before Raspberry pi configurations.

You can take this example Google sheet (make a copy to yourself and format for your needs):

example google sheet

Here are two charts for temperature and humidity for several days:

And this is how the raw data looks like:

Let's see how to configure RPi and google sheet scripts and web app deploy to enable this "data flow gateway".

1. go to the "script" menu to open the google sheet corresponding and pre-programmed small script:

or you can download the script code file too from the repo here

2. select publish->deploy as web app from the menu there:

3. copy that link (the most important thinkg) which needs to be paste in the future steps into the Rapsberry Pi code (see below in step 8). This key makes a "link" between the RPi and the Google web app server, thus the data will be uploded into the right place: your google sheet.

After the google sheet configuration now see what configuration we need to do under the hood of Raspberry Pi:

4. enable I2C interface at Raspberry Pi

   sudo raspi-config

4b. connect the sensor to the RaspberryPi's corresponding pins as shown below:

5. update + upgrade and install i2c-tools to be able to reach the sensor and check its status

sudo apt update
sudo apt upgrade
sudo apt install i2c-tools

6. veryfication of I2C sensor:

sudo i2cdump -y 1 64

#should look like somthing like this:

7. creating log script to execute I2C sensor call and google web app data upload:

sudo mkdir /usr/local/bin/log
cd /usr/local/bin/log
sudo nano log

8. copy paste this into log, take care to modify the web app key what you copied at setp 3 above

#/bins/sh
DATA=`sht21.py`
curl -L "https://script.google.com/macros/s/**copy your Google script deployed web app key here**/exec?$DATA"

9. set rights

sudo chmod +x log

10. copy the python script into the proper folder:

cd /usr/local/bin/
sudo wget https://raw.githubusercontent.com/DecentLabs/officeAir/master/sht21.py
sudo chmod +x sht21.py

11. modifying crontab to execute the script every minuite

sudo nano /etc/crontab

11b. and copy paste to the last line this:

*  *    * * *   root  /usr/local/bin/log/log #log air quality

Finally reboot the RPi, once it comes back it should report temperature and humidity values every minute to the google sheet

sudo reboot

🚀 ESP32 Port (esp32_version/) added on 02/07/2026

This subdirectory contains a complete C++ (Arduino framework) port of the original Raspberry Pi Python project. It migrates the climate logging system to an ESP32 microcontroller (specifically optimized for the Heltec WiFi LoRa 32 V3 board), maintaining 100% backward compatibility with the existing Google Apps Script and Google Sheets backend.

🔄 What Changed? (Raspberry Pi vs. ESP32)

Feature	Original Version (Raspberry Pi)	Upgraded Version (ESP32)
Hardware	Raspberry Pi (Single Board Computer)	ESP32-S3 (Heltec WiFi LoRa 32 V3)
Language	Python (sht21.py) + Bash script	C++ (Arduino / PlatformIO)
Power Consumption	High (~2W to 5W), always-on	Ultra-low (Micro-amps) via Deep Sleep
I2C Protocol	Linux /dev/i2c-1 system calls	Hardware I2C via Wire library
HTTP Requests	Native curl -L CLI command	HTTPClient with strict redirect following
Form Factor	Large, requires robust 5V power supply	Compact, battery/solar friendly, runs on Micro-USB/Type-C

🛠️ Technical Improvements

1. Power Management & Deep Sleep: Unlike the Raspberry Pi which must run 24/7, the ESP32 wakes up, connects to Wi-Fi, reads the sensor, pushes the data to Google Sheets, and immediately enters Deep Sleep for 10 minutes. Additionally, it utilizes the Heltec V3's onboard Vext power switch (GPIO 36) to completely cut off power to the external I2C sensor rail during sleep, minimizing standby current draw.

2. Custom I2C Pinout: The SHT21 sensor has been mapped to custom I2C pins appropriate for clean prototyping on the Heltec V3 board:

   • SDA: GPIO 41
   • SCL: GPIO 42

3. Google Web App Redirection Handling: Google Apps Script URLs automatically trigger a HTTP 302 Redirect. The ESP32 code is explicitly configured with http.setFollowRedirects(HTTPC_STRICT_FOLLOW_REDIRECTS); to natively handle this behavior, ensuring successful payload delivery (returning HTTP 200 Ok).

---

📂 Directory Structure

esp32_version/
├── platformio.ini   # Project configuration, dependencies, and board definitions
└── src/
    └── main.cpp     # Main C++ source code (Wi-Fi, SHT21 driver, HTTP client, Deep Sleep)