Hack All the Things in the Time You Save with This LED Pomodoro Timer

Do you want to use your time more productively but are tomato-averse? [Robin]‘s LED Pomodoro timer could be the perfect hack for you.

The Pomodoro Technique is a time management solution developed in the late 1980s. The basic idea is to spend a very focused 25 minutes performing some activity such as working or studying and then take a 5-minute break. Many of its proponents use a tomato-shaped kitchen timer to alert them to switch between the two states, but [Robin] wanted to make his own and learn along the way.

First, he wanted to use an ATtiny85 and learn about its features. Specifically, he used its timers, PWM, and low-power sleep mode. [Robin] used Charlieplexing to drive a total of six LEDs. When the timer starts, five yellow LEDs are driven high to indicate each 5-minute slice of work time. A red LED is lit during the 5-minute break.

[Robin] also explored compact PCB design and fabrication. All components are SMD and his board is 4cm square. [Robin] is using this SMD buzzer for discrete feedback. He included a footprint for a six-pin ISP header and programmed it with pogo pins. The timer is completely interrupt-driven: one click of the tactile button starts the work counter, and the buzzer sounds when time is up. A second click starts the break counter.

[Robin] has made everything available in his GitHub repo and encourages you to use it. Time’s a-wastin’!


  1. Alex says:

    where’s the arduino?

  2. Nick Johnson says:

    I think the very clever layout of the tracks for the charlieplexed LEDs deserves a call out. Nicely done!

  3. I have my own time-management system – it’s called a piece of paper ;-)

    Very nice build – love the board layout! I need to try playing with charlieplexing at some point.

  4. vonskippy says:

    There’s an App for that. Seems a tad superfluous making a custom bit of hardware to do what every smartphone can already do. Plus the app’s turn off the distractions that are on the phone (i.e. ringing, email alerts, sms alerts, etc.).

  5. icanhazadd says:

    Don’t think most employers would be cool with taking 14 5 minute breaks in a shift.

    • justice099 says:

      *shrug* My job would be fine with it (electrical engineer.) And I would assume any job that is project based would also be fine with it.

      Any job where you are required to use your brain and concentration, how much productivity are you going to get out of someone if they are mentally fatigued? It’s not like you really stop thinking about it when you walk away. I find that when I am stuck on a problem that if I head out for a walk around the building I usually come back in with the solution. Sometimes I pull out my hand-held tetris game and play a round. My mind is still working on the problem, I am just giving it a break from the pressure.

      If your productivity depends on your creativity, concentration, and problem solving skills, there is no point in trying to force it. It doesn’t work.

      In fact, I think that’s the entire goal of this. For one, if you have multiple projects going on, it is too easy to get overwhelmed trying to work on all of them at once. What happens is that you end up just spinning your wheels on each one and they take much longer than it would if you could just focus on one at a time. And finally when the deadlines approach, you drop everything else and focus and magically you are done in no time.

      My work actually has re-iterated through training sessions this exact technique several times (but didn’t give us timers.)

    • Whatnot says:

      I think the reality of things is that people are doing nothing half the time in the majority of jobs. (majority might not apply in china, but probably is in north korea).

    • Ren says:

      A friend of mine worked as a software programmer for TRW (~20 years ago). They expected every 1/10th hour (6 minutes) to be billed to some Project Number.

  6. CNLohr says:

    More everything-on-one-layer people! We need to form a club! J/w why didn’t you go with an SMT 6 pin ISP header?

  7. Pyk says:

    I look at the PCB (specifically battery & mount) and all i can see is a cat. Now its seared into my brain

  8. Nice pcb and soldering. When I solder smd parts on a naked (non-soldermask) pcb like this the solder blobs tend to spread out far too long on the tracks.

    But I would have put the decoupling cap closer to the chip – actually – is there a cap for the chip at all?

  9. MRE says:

    I hope it took less than 25 minutes to design.. or bing bing fail! heh.. but seriously, I like the timed work idea, but just cant be forced to take a break sometimes, while other times I take too many. hmm..

    • Whatnot says:

      Actually now that you mention it, I think that if I had a timer running all day it would unnerve me, always counting down, making me nervous and tense.

    • fakufaku says:

      You got me there! :)
      I also found that the technique needs to be adapted depending on the job. Typically, it is great to attack tasks I am putting off. For things I like, I can concentrate for longer.

      • MRE says:

        Ok yeah. I can see it doing great things for me on my list of procrastinated projects. Get 20 minutes of good hard work on it, followed by ‘mendokusai’ time (cant be bothered.. back to procrastinating).

  10. LMchief says:

    I’m using this same style battery and clip holder for a project of mine. I want to put a gold contact pad on the negative contact (to prevent oxidation on the pad). But repeated searches on Digikey have been fruitless. Anyone have a part #? Any help would be appreciated.

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