Dayclock

ESP32 based day clock + sensors

This is mixup of https://github.com/phreakmonkey/DayClock 's 3D printed pointer and hemispherical day clock with my code to move the pointer within the day, as well as integrating with a DHT temperature/humdity sensor and a MHZ-19B carbon dioxide sensor and providing HTTP endpoints (HTML/XML/JSON) and pushing data out via UDP.

Parts needed for this design:

• ESP32 (ESP8266 should work, but is untested).
• DHT11, DHT22, or AHT20 (preferred) temperature/humidity sensor. Lots of these online - AdaFruit sells the DHT sensors and a resistor, but you might prefer an integrated package with the circuit board and resistor built in. Search on eBay, etc. Expect to spend no more than $10 and probably much less. AHT20 is available at both AdaFruit and SparkFun.
• MHZ-19B CO2 sensor. These are all over eBay and the usual sources. Look around and don't spend more than around $25 for a nicely packaged version.
• LCD panel with I2C interface. These are typically 1602a type devices and should cost a few dollars or so on the usual places. The code defaults to a 16x2 display - larger displays might work but YMMV. There are plenty of 3D designs available to hold these LCD screens - I used and liked https://www.thingiverse.com/make:440729
• 3D printed versions of phreakmonkey's https://github.com/phreakmonkey/DayClock/blob/master/DayClock.stl and https://github.com/phreakmonkey/DayClock/blob/master/DayClock-hand.stl
• A generic "9G" servo motor or equivalent.

Configuration: The Arduino .ido file has a configuration section at the top of the code. You will need to configure, at least:

• ssid and password - set these to your WiFi network's settings
• gmtOffset_sec and daylightOffset_sec - these will depend on your location.

as well as:

• You will probably also need to adjust the dayPos and SERVO_MIN and SERVO_MAX values, although this can wait until you have phreakmonkey's parts printed and assembled with the servo. The default values work well with my servo/print, but you will likely need to adjust some or all of these values.
• You may also wish to uncomment the DISPLAY_CELSIUS to use celsius units for the LCD and HTTP interfaces.
• If you plan to have the UDP XML push messages enabled, set up UDP_HOST_IP and UDP_HOST_PORT.

The default pinout configuration is:

• Servo: GPIO Pin 13
• DHT: 5V, GND, GPIO Pin 14
• LCD: 5V, GND, SDA -> I2C SDA, SCL -> IC2 SCL
• MH-Z19B: RX -> TX2, TX -> RX2

Software / Libraries used (and much thanks given!):

• https://github.com/adafruit/Adafruit_Sensor
• https://github.com/espressif/arduino-esp32
• https://github.com/adafruit/DHT-sensor-library
• https://github.com/adafruit/Adafruit_AHTX0
• https://github.com/jkb-git/ESP32Servo
• https://github.com/fdebrabander/Arduino-LiquidCrystal-I2C-library
• https://github.com/WifWaf/MH-Z19
• https://github.com/me-no-dev/ESPAsyncWebServer
• https://github.com/chartjs/Chart.js

Suggestions:

• If you're using a small breadboard and a ESP32 with male pins, remove the +/- rail on the breadboard and snap two breadboards together so the ESP32 module will fit with room to wire up the connections.
• MHZ-19B is pretty touchy - read https://github.com/WifWaf/MH-Z19/blob/master/README.md for the details.
• Superglue phreakmonkey's dayclock print to the niq_ro's 1602a stand print to make a nice integrated unit. Then stick down the DHT and MHZ-19B to the breadboard. There are some nice 3D prints on Thingiverse for the DHT models - I like https://www.thingiverse.com/make:679955 which, scaled up, also works well for the MHZ-19B sensor.

HTTP - there are a number of views into the DayClock's data

• / - a webserver is running on the ESP that defaults to showing the current temperature/humidity/CO2 level/timestamp. This will either reload every 5 seconds for a non-Javascript browser or will update automatically.
• /xml - this is a XML representation of the last sensor read values
• /json - this is the same data as XML, provided in JSON format. This is also used by the default handler to automatically update the page.
• /history - 24 hours of per-minute sensor history, provided in JSON format. Used by /chart.
• /chart - a Chart.js based HTML5 page that displays temperature, humidity (disabled by default), and CO2 levels over the past 24 hours. Automatically updates every 60 seconds.

OTA Updates:

• /update allows over the air updates of the firmware