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https://github.com/xtrinch/esp32s2-bme280-webusb

A web-usb enabled application running on ESP32S2 supporting displaying sensor data on a Waveshare e-paper display / sending sensor data to the cloud
https://github.com/xtrinch/esp32s2-bme280-webusb

bme280 epaper esp32s2

Last synced: 3 months ago
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A web-usb enabled application running on ESP32S2 supporting displaying sensor data on a Waveshare e-paper display / sending sensor data to the cloud

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README 

        
# esp32s2-bme280-webusb



Sends periodic `bme280` humidity, temperature, pressure and battery voltage data from `esp32s2 development board` to [sensor dashboard](http://iotfreezer.com) backend via Wi-Fi. 



Is configurable via a [web interface](http://iotfreezer.com/) using webusb. Since the board uses native usb communication, the serial output will also be emulated via USB so it may not work as you would expect a regular serial connection - if it's configured wrongly, there will be no output in your serial monitor. If the board sleeps, when you connect it to USB, you will not be able to flash it. Board needs to be wide awake and listening to USB commands for flashing to work. When the board is connected to the computer - the neopixel of the esp32s2 will light up and the display should display `PC` instead of the usual measurements.



If you botch the code and manage to put it to sleep when on USB, boot the board into bootloader mode by holding the button `BUT1` on the board when connecting to USB, then you will be able to flash via USB again.



Currently, this firmware can make it around 7 months on a 1200mA battery connected to the dev board. The board can be configured to send the measurements to the server once every N times via the parameter `maxRtcRecords` to optimize battery time.



Built with PlatformIO.



See also [backend](https://github.com/xtrinch/sensor-dashboard-nestjs-backend) and [frontend](https://github.com/xtrinch/sensor-dashboard-react-frontend) repo, or [see it live](http://iotfreezer.com/) with some sensor data from my living room.



## Components

- ESP32S2 dev board with native usb support, meaning there should not be a usb to serial converter on the board, I used [ESP32-S2-DevKit-Lipo-USB from Olimex](https://www.olimex.com/Products/IoT/ESP32-S2/ESP32-S2-DevKit-Lipo-USB/open-source-hardware)

- Waveshare e-paper 1.54inch display - black and white version

- Bosch BME280 sensor module

- 3.7V LiPo battery (or other), e.g. [BATTERY-LIPO1400mAh from Olimex](https://www.olimex.com/Products/Power/BATTERY-LIPO1400mAh/)



## Additional things needed to assemble the PCB

- PH2.0 8 pin connectors for the display (bent needle for the PCB)

- min 2, max 4 2.0mm high spacers to mount the display above the ESP32S2, depending on how many sides of the display you want to fixate

- PH2.0 2pin connector for the battery (if the battery doesn't already come with one)

- bunch of male / female headers

- 1x push button - right angled for RESET button

- 1x push button - regular for BOOT button



## Setup



1. Have a sensor dashboard backend running (see https://github.com/xtrinch/sensor-dashboard-nestjs-backend) or use [iotfreezer](http://iotfreezer.com/).

2. remove the solder from `LED1_ENABLE SMD` jumper (i.e. open it) on the ESP32S2, because it consumes a large current 

3. solder the `BAT_SENS` and `PWR_SENS` jumpers on the ESP32S2, to be able to detect battery voltage levels

4. Uncomment the part in `main.cpp` that routes VREF to a GPIO on the ESP32S2. Program the board, measure VREF and input it into `import_env.py` under `REF_VOLTAGE` (if it's e.g. 1.1, input 1100). This will be needed for accurate battery measurement and you cannot skip this step.

5. Copy `import_env.example.py` to `import_env.py` and define your sensor dashboard url.

6. Run `pio run -t buildfs && pio run -t uploadfs` to upload the icons the display uses for humidity/temperature

7. While having your board plugged into the computer, reboot the board and configure it via the web interface (via webusb) of the sensor dashboard (iotfreezer).



## Troubleshooting



If you cannot upload to your board on linux, input `sudo chmod a+rw /dev/ttyUSB0`.



To monitor across reboots, as uploading and monitoring does not work, use the following command on Linux:

`while [ true ]; do cat /dev/ttyACM0; done`

 

To check out the usb descriptors, run `lsusb -v`. To check out the kernel logs for errors, run `dmesg`.

## Convert icons



 `convert temperature-2-48.png -background white -alpha remove -alpha off -compress none -depth 24 -resize 48x48 temp-final.bmp`



## Production deploy



Make sure to turn off `DEBUG` to save power.



## PCB



See `schematics-w-display` folder for full project. It was drawn in KiCad and it's a two sided PCB.



![Image of Yaktocat](https://github.com/xtrinch/esp32s2-bme280-webusb/blob/master/images/pcb.jpg)



## End product with casing



Casing is parametric and drawn in FreeCad 0.19. It is made to fit the above PCB. For FreeCad project, see `casing-w-display` folder.



![Image of Yaktocat](https://github.com/xtrinch/esp32s2-bme280-webusb/blob/master/images/casing1.jpg)

![Image of Yaktocat](https://github.com/xtrinch/esp32s2-bme280-webusb/blob/master/images/casing2.jpg)



# TODOs

- use ULP to use power pin as ADC wakeup source

- reference ADC voltage to parametrizable params?