https://github.com/robthree/temperaturedisplay
Measures temperature and humidity using a GXHT30 and displays this information on an SSD1306 OLED display. Offers a HTTP endpoint to read values as JSON, also outputs values on serial.
https://github.com/robthree/temperaturedisplay
cpp electronics esp8266 ghxt30 ghxt30-sensor hardware platformio serial serial-communication smarthome smartmeter ssd1306 ssd1306-oled temperature temperature-monitoring temperature-sensor wemos wemos-d1 wemos-d1-mini
Last synced: about 1 month ago
JSON representation
Measures temperature and humidity using a GXHT30 and displays this information on an SSD1306 OLED display. Offers a HTTP endpoint to read values as JSON, also outputs values on serial.
- Host: GitHub
- URL: https://github.com/robthree/temperaturedisplay
- Owner: RobThree
- Created: 2025-03-19T23:37:12.000Z (about 1 year ago)
- Default Branch: main
- Last Pushed: 2025-03-20T00:16:26.000Z (about 1 year ago)
- Last Synced: 2025-03-20T01:24:39.986Z (about 1 year ago)
- Topics: cpp, electronics, esp8266, ghxt30, ghxt30-sensor, hardware, platformio, serial, serial-communication, smarthome, smartmeter, ssd1306, ssd1306-oled, temperature, temperature-monitoring, temperature-sensor, wemos, wemos-d1, wemos-d1-mini
- Language: C++
- Homepage:
- Size: 72.3 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
#  Temperature Display
Uses an Wemos D1 mini with a GXHT30 I²C temperature & humidity sensor and a SSD1306 I²C 0.96" OLED display.
This project supports OTA updates, uses the WiFi manager to configure the WiFi and provides a REST API to get the temperature and humidity as JSON. The readings (and display) are updated every 2 seconds (by default, configurable) and also output to serial.
## Hardware
You'll need:
* [Wemos D1 mini or clone](https://aliexpress.com/w/wholesale-wemos-d1-mini.html)
* [GXHT30 I²C temperature & humidity sensor module](https://aliexpress.com/w/wholesale-GXHT30-module.html)
* [SSD1306 I²C 0.96" OLED display](https://aliexpress.com/w/wholesale-SSD1306-0.96%22.html)
* 2x [2.54mm female header 8 pins](https://aliexpress.com/w/wholesale-2.54mm-female-header-8-pins.html)
* 2x 8 pin and 2x 4 pin [2.54mm pin headers](https://aliexpress.com/w/wholesale-single-row-male-2.54mm.html)
All of these components are readily available at the time of writing, you should be able to easily source them.
### PCB
The [`pcb`](/pcb/) directory contains the KiCad (9.0) design files for the Wemos D1 mini shield PCB. [PCBWay](https://www.pcbway.com/) reached out to me and was kind enough to support this project. The project is available at [PCBWay's Shared Projects](https://www.pcbway.com/project/shareproject/Temperature_display_f0e459fd.html) for easy ordering.
 [](https://www.pcbway.com/) 
[](/img/PCBWay/7.jpg) [](/img/PCBWay/6.jpg) [](/img/PCBWay/8.jpg)
For more pictures of the PCB and/or project see [the project page](https://www.pcbway.com/project/shareproject/Temperature_display_f0e459fd.html) or the [/img/PCBWay](/img/PCBWay/) directory. I would like to thank PCBWay again 🙏 Shipping was incredibly quick 🛫🛬 and the PCB is perfectly finished 👌
In a next iteration I'm hoping to integrate the GXHT30 on the shield, but being pretty new to PCB design this first iteration uses a module.
### DIY
Connect the GXHT30 and SSD1306 to the Wemos D1 mini's `3v3` pin, connect the grounds of all three modules. And connect `SDA` to `D2` (`GPIO4`) and `SCL` to `D1` (`GPIO5`). That's it. Done. Apparently some modules require 5V; if your display is glitching or not turning on, try connecting it to the 5V pin on the Wemos D1 mini. I power the project via the Wemos' onboard USB port but you should also be able to power it by directly powering the power pins.
```
+----------+ +------------------+
| GXHT30 | | SSD1306 |
| [X] | | |
| | | |
| V G S S | | V G S S |
+-----------------+ | C N D C | | C N D C |
| Wemos D1 mini | | C D A L | | C D A K |
| (ESP8266) | +----------+ +------------------+
| | | | | | | | | |
| D1 |-------|-|--|-+---------------|--|--|--+
| D2 |-------|-|--+-----------------|--|--+
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| GND |-------|-+--------------------|--+
+--| 3V3 | | |
| +-----------------+ | |
+----------------------------+----------------------+
```
### Tips on assembly:
* ⚠️ On some displays [there's a capacitor that can get quite close to the pins of this board](/img/pin.jpg). You might want to take a sidecutter and snip of a piece of the pin or use some kapton tape or some other means to isolate the pin. Make sure you check BOTH left and right side of the display!
* Solder the pinheaders/sockets **first**, and only **then** solder the display / temperature sensor. If you solder the display first you'll have a hard time reaching the pins connecting the board to the Wemos D1 mini
* When soldering the display to the board, [use a female header as a spacer](/img/spacer.jpg) for the perfect alignment.
* You don't _need_ to use male/female headers to connect the Wemos D1 mini to the PCB, you can use pins-only to make the device more compact. Just make sure you keep enough clearance!
* Don't forget to emjoy the peel-feel when removing the protective peel from the OLED 🤤
## Software
This is a PlatformIO project. I'm sure someone will help convert this to an Arduino IDE project, but it's not going to be me.
### How to get started
1. Open this folder in [PlatformIO for VSCode](https://platformio.org/platformio-ide)
2. Copy [`include/example_config.h`](include/example_config.h) to `include/config.h` and change the OTA update password and **devicename** (this one is optional)
3. Copy [`example_env_secrets.ini`](example_env_secrets.ini) to `env_secrets.ini` and set the same password for the `--auth` option
4. ⚠️ Make sure your [`platformio.ini`](platformio.ini) file has `default_envs` set to `d1_mini_serial`
5. Connect your USB cable to your device and the Wemos D1 mini
6. Compile the project and upload via (USB virtual) serial to your Wemos D1 mini
7. You should now be able to connect to a WiFi AP named after your **devicename** (see step 2); connect to it, set your WiFi credentials and save
8. The Wemos D1 mini should reboot and the OLED display should (shortly) show the IP; the display should show any other errors or problems as well
9. Next time you update you can use the OTA configuration (`default_envs` set to `d1_mini_ota` and the correct IP in `env_secrets.ini` at the `upload_port` entry), no more need for USB cables
### Once it's up and running
The display will show the temperature in °C or Fahrenheit (see `include/config.h`) and the humidity in %RH (Relative Humidity). If your sensor is way off you can fix this by setting `TEMPERATUREOFFSET` and/or `HUMIDITYOFFSET` in `include/config.h` and updating the device or, much easier, by using the web UI. The temperature and humidity will also be output to the serial port every time the sensor is read (see `UPDATEINTERVAL`) and when you use the `/read` endpoint of the REST API (e.g. `http:///read` [`GET`]) you'll get the readings as json:
```json
{
"celsius": {
"temperature": 22.81,
"offset": -5
},
"fahrenheit": {
"temperature": 73.058,
"offset": -9
},
"humidity": {
"relative_perc": 31.29,
"relative_perc_offset": 8
},
"wifi": {
"rssi": -48
},
"lastupdate": "1.62 seconds ago",
"display": "c",
"devicename": "MyDevice"
}
```
These values are only updated every time the sensor is read (again: see `UPDATEINTERVAL`). There is also a `/reset` endpoint ([`PUT`]) that will reboot the device.
Finally, the device also offers a user-friendly UI at the `/` endpoint (e.g. `http:///`) which updates every 5 seconds:
You can find the settings at `http:///settings` or by clicking the cog in the top right corner of the home screen. The settings screen allows you to adjust some values. Once your changed settings have been saved you can go back home by clicking the 'home' icon in the top right corner.
## Attribution
* PCB design based based on [Jérôme Labidurie](https://github.com/jerome-labidurie)'s [Wemos D1 mini Shield template for KiCad](https://github.com/jerome-labidurie/d1_mini_kicad)
* Logo from [SVG Repo](https://www.svgrepo.com/svg/179515/thermometer-temperature) (CC0 License)