🕐 Kroneum

Disclaimer: I needed a dumb, autonomous, configurable and GUI-less physical timer to better manage my own time during the day and that is how Kroneum was born. Another goal was to see how well Rust fits into embedded development (basic interactions with MCU, USB stack and I2C driver).

Kroneum is an experimental, accessible (no GUI) and fully open source (both in code and hardware) time tracker device.

There is neither GUI/LCD nor Wi-Fi/Bluetooth interface available, just two buttons one can use to configure the timer. More advanced users can use built-in USB functionality to configure device (via dedicated CLI tool with optional Web interface), upgrade firmware (via DFU interface) or upload various Krouneum "recipes" (e.g. to repurpose device completely).

Usage

By default device stays in a standby low power mode and wakes up as soon as any of the button is being pressed for 3-5 seconds. As mentioned above there are just two buttons: Ⅰ (Roman one) and Ⅹ (Roman ten).

Long press on Ⅰ or Ⅹ button when in StandBy mode - device enters into Setup mode
Short press on Ⅰ when in Setup mode - increases desired timer by one unit
Short press on Ⅹ when in Setup mode - increases desired timer by ten units
Long press on Ⅰ when in Setup mode - sets timer treating unit as a second (see example below)
Long press on Ⅹ when in Setup mode - sets timer treating unit as a minute (see example below)
Long press on both Ⅰ and Ⅹ when in Setup mode - sets timer treating unit as an hour (see example below)
Long press on Ⅰ or Ⅹ when in Alarm mode - resets current alarm if any and enters Setup mode
Long press on both Ⅰ and Ⅹ when in Alarm mode - resets current alarm if any and enters StandBy mode
Very long press (5 seconds) on both Ⅰ and Ⅹ - enters Configuration mode and powers up USB interface

Once timer fires up it will be repeated every 10 seconds (configurable) until it's acknowledged by the long press on both Ⅰ and Ⅹ.

Examples:

Long Press on Ⅰ + 5 short presses on Ⅰ + long press on Ⅰ = 5s timer
Long Press on Ⅰ + 5 short presses on Ⅰ + long press on Ⅹ = 5m timer
Long Press on Ⅰ + 5 short presses on Ⅰ + long press on both Ⅰ and Ⅹ = 5h timer
Long Press on Ⅰ + 1 short press on Ⅰ + 2 short presses on Ⅹ* + long press on Ⅰ = 21s timer
Long Press on Ⅰ + 1 short press on Ⅹ + long press on Ⅹ = 10m timer
and so on

Configuration

Advanced users can configure device via USB with the help of dedicated CLI tool, assuming device is in Configuration mode and connected to the host PC via micro USB cable:

$ cargo run -- info

$ cargo run -- beep -n5

$ cargo run -- alarm get
$ cargo run -- alarm set "5m 15s"

$ cargo run -- flash read 0x1f
$ cargo run -- flash write 0x1f 10
$ cargo run -- flash erase

$ cargo run -- reset

It's also possible to use CLI tool as a standalone server with a minimalistic Web interface:

$ cargo run -- ui
  Running Kroneum Web UI on http://127.0.0.1:8080

Web server is bound to a local http://127.0.0.1:8080 address and can be accessed with any modern browser:

enclosure

Run cargo run -- help for more details.

NOTE: To use CLI tool without root privilege you may need to add the following udev rule:

/etc/udev/rules.d/50-kroneum.rules
----------
SUBSYSTEMS=="usb", ATTRS{idVendor}=="1209", ATTRS{idProduct}=="deed", GROUP="users", MODE="0660"

And then manually force udev to trigger this rule:

# udevadm trigger

In the future releases Web interface will be using WebHID API completely eliminating the need in the local Web server.

Building custom firmware

If you feel adventurous you can easily build and flash custom firmware to Kroneum. You can use ./scripts/flash.sh script from fw folder to build and flash default firmware or few custom examples:

Default firmware:

# Default firmware
$ ./scripts/flash.sh 

# Example: blinking through TP1/SDA pad exposed on the back side of Kroneum PCB
$ ./scripts/flash.sh blinky

# Example: interfacing with SSD1306 LCD via TP1/SDA and TP2/SCL pads exposed on the back side of Kroneum PCB
$ ./scripts/flash.sh i2c_ssd1306

The flash.sh script is essentially consequent calls of cargo build --release ..., cargo objcopy --release ... and dfu-util ....

Prototype or DIY

Schematics is done in KiCad and can be found here. PCB includes SWD, I2C and CR2032 connectors and may look a bit oversized because of that, but on the bright side hand soldering and CNC engraving was a breeze.

The most recent enclosure was machined from 5mm (base and cap) and 2mm (buttons) Delrin and the older versions were machined from 5mm Plexiglas (walls and buttons) and 2mm Delrin (base and cap). G-Code can be found here.

See PCB and enclosure renders and photos of how it turned in real: