Pomoduino2

This project is a simple pomodoro hardware timer using arduino uno with 16x2 lcd display, 2 buttons and a buzzer.

It keeps track of finished pomodoros (saves them to non-volatile memory) and counts them up. The logic is described below.

A prototype with Arduino looks like this:

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... and using nano - like this:

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Logic - description

There are 3 timers:

• 25 minutes (aka pomodoro),
• 5 minutes (aka short break),
• 15 minutes (aka long break)

Pressing (and releasing) button 1 (B1) cycles through them.

Pressing (and releasing) button 2 (B2) starts a timer.

When timer elapses it goes automatically to a next one, as described in pomodoro method, i.e. 25 - 5 - 25 - 5 - 25 - 5 - 25 - 15 - 25 - 5 ...

Number of finished pomodoros is visible in the top right corner and also visualized as a progress bar in the bottom line.

Pressing B2 while running pauses the state. Pressing (and releasing) again makes it continue.

Holding B2 longer (3s) during pause cancels the timer - it goes back to ready state.

Holding B2 longer (3s) in ready state clears the number of pomodoros done so far.

The pomodoros are stored in eeprom and thus survive power off.

On a diagram it looks like so:

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The drawing was made with draw.io.

Schematic

The components were connected as depicted below:

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Building

Hardware

• arduino - I used uno and nano328 but should work with others too. As you can see it just uses input from 2 buttons and several outputs (LCD, buzzer) so it could be adapted to any device having digital I/Os

• 16x2 LCD display - although the software is made so that the UI class, which now uses LCD, can be easily replaced by literally anything. As an example there is src-alternative/ui/serial/UI, which spits out something on Serial console depending on current state. Yet another example (included) is a variant using 5 LEDs as "user interface".

• 10k potentiometer (optional) - for controlling contrast. If you don't want that just use some resistor placed between V0 pin of the LCD and ground. For me 3.3k Ohm worked well, however using a capacitor (100uF) as you can see here: here worked best (forming simple RC filter with D5 as PWM).

• 2 buttons

• buzzer - although, again, it can be replaced by any device controller by digital output, for example a LED.

Software

Quickstart

I'm using debian so I could do just this:

$ apt-get install arduino arduino-mk cmake g++

Then in the directory where this repository was cloned:

$ make lcd # to build a ready to use version
$ make upload # to upload compiled binary to the arduino

If you want to play a bit with it there are few more commands, like:

$ git submodules update --init # to fetch google tests/mock
$ make test # to compile and run tests

$ make lcd-debug # to build a debug version (see below)
$ make serial-debug # to build a debug version with UI_Serial instead of UI_Full

Some explanations

To compile I used arduino-mk. I really recommend that as an alternative to the official IDE - especially if you would like to:

• use your favourite text editor,
• be able to easily adjust compile options
• make automated builds and testing.

That code is very likely to work using the standard arduino IDE, provided that the files are put in right directories. But I neither tested that nor plan to.

The debug target adds some extra debug messages which are spit out on serial interface (with picocom /dev/ttyUSB0 you can watch it) AND it changes times of pomodoro periods from minutes to seconds which is very useful for testing.

For testing the code I used [google test] which also includes google mock. I used both as submodules (they are in /modules directory). It matters of course only if you need/want to run tests.

License

MIT

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Documentation was tested using dillinger.io.