Chronodecahedron

https://esphome.io/ powered physical time-tracking dodecahedron.

Licensing

• AGPL-3.0 or later applies to the code and configuration configuration.yaml
• CC-BY-NC-4.0 applies to the 3D-model, description and other support material

Project is WIP, but close to completion

Documentation is lacking at some points, but this is personally not a high priority. The design is mostly settled, but might get some minor touchups. Software might need some improvements, especially for keeping a usage history on the ESP. Right now, this needs to be done manually.

What is this?

This device is a physical time-tracking device to easily track how long you work on what.

It consists of a 3d-printed dodecahedron (12 sided platonic solid) and uses an accelerometer to detect which side faces up.

By using esphome as a platform, it is then able to expose the detected side as a sensor over MQTT or other protocols.

Check out the model on a360.co. The STL and f3z are available in this repo.

Use-Cases

• Tracking time for projects (E.g. freelancers that switch between projects)
• Use as scene-selector in home automation setups

Feel free to open PRs to extend this list :)

What do I need?

Tools

• Soldering Iron
• Desoldering tools
  • Pump, wick or whatever you are able to use
• 3D Printer

Parts

Name	Pcs	Note
Prints
Printed hull.stl	1	Use your preferred color+material
Printed base.stl	1
Mechanical
M3 threaded inserts	2	Optional, depending on tolerances
M3x8 screws	2	Can be shorter
M2 threaded inserts	2	Recommended
M2x8 screws	2
Double-sided tape
Electrical
Lolin32 Lite	1
GY-521 (MPU-6050 Accelerometer)	1
Resistor 200kΩ THT	2	Other large sizes fine, too(50kΩ-500kΩ)
Li-Ion battery (with protection)	1
Jumper wire		GND/INT conection
6x2.54mm pin header	1	Direct connection of the GY-521
Solder

Assembly

0) Sourcing

• Source the parts on your own
• Print the parts with whatever material you prefer

1) Threaded Inserts

• Melt the two M3 inserts into the holes of the printed hull.stl
• Melt the two M2 inserts into the two blind holes of the printed base.stl

2) Electronics

• (Optional: Desolder the JST-PH header for the battery)
• Desolder the LED on the GY-521 (white component next to the x-axis silkscreen)

Before	After

• Stick both resistors with one lead through GPIO33 and make a solder connection
• Solder the other lead of one of the 100kΩ resistors to the +-pad of the battery connector
• Stick the other lead of the second resistor through GND, but don't connect it yet

• Put a piece of jumper wire (~6cm) through GND, now solder both the resistor and wire to GND
• Solder another short piece of jumper wire (~2cm) on INTof the GY-521
• Break away one of the pins of the pin header (you will have one single pin and a row of 5)
• Solder the single pin on VCC of the GY-521, the remaining row on the pins SCL to ADO

• Solder the other end of the long jumper wire to GND of the GY-521 (shown here without Board on the other side)

• Solder the GY-521 into 3V to GPIO17 of the Lolin32 Lite (This will leave GPIO22 and GPIO16 unconnected)
  • Make sure that it's relatively parallel to the Lolin32 Lite
• Solder the other end of the short jumper wire to GPIO13 of the Lolin32 Lite
• Cut the pins on the back of the lolin32 flush

• (If you removed the JST-PH jack: Solder the battery to the pads))

3) Firmware

• Modify the yml-files in the esphome directory to your needs (especially secrets.yml)
• Connect the Lolin32
• Run esphome run chrono.yml in that directory
• Check that it works as expected (Side detection, battery level, battery charging)
  • The battery level might require fine-tuning. Measure the actual battery voltage level and compare it to the raw reported one.

4) Assembly

• Use the M2 screws to attach the Lolin32 to the base.stl

• Use the double-sided tape to attach the Li-Ion battery to the inside of the hull.stl

• Close the base.stl and the hull.stl and connect them with the M3 screws.

chronodecahedron-watcher

./src contains a small python script that connects to MQTT and dumps the state of the cube in a csv-like fashion (separator is - space), for easier processing in spreadsheets.

It can also be configured as a service on NixOS devices by:

• Adding this repository as a flake input, e.g.:

    chronodecahedron = {
      url = "github:CRTified/Chronodecahedron";
	  # We only use basic library functions and packages, following your nixpkgs should be safe:
      inputs.nixpkgs.follows = "nixpkgs"; 
    };

• Importing chronodecahedron.nixosModule as a module
• Configuring the service under services.chronodecahedron-watcher, e.g.:

  services.chronodecahedron-watcher = {
    # Make it depend on mosquitto
    enable = config.services.mosquitto.enable;
    user = "chronos";
    group = "chronos";
	
    mqttServer = "localhost";
    mqttPort = 1883;
	
    mqttCredentialsFile = "/var/keys/mqttAuth";

    device = "timecube";
    logFile = "/root/chronodecahedron.csv";
  };

Note that credentials bypass the nix store and are stored in /var/keys/mqttAuth. This file needs the following entries adapted to your need:

CHRONO_MQTT_USER=$mqttuser
CHRONO_MQTT_PASS=$mqttpass