Shmoocon: Advanced Low Power Techniques And A Watch

Real quick question: how do you increase productivity at work? The greatest (highest paid) minds would just say: do agile or scrum or something. What’s scrum? That’s where you gather ’round every morning for a waste of time meeting that kills your every desire to be productive. A while back, [Travis Goodspeed] was stuck in some lesser circle of hell like this and in an effort to be polite by not looking at his phone too much, looked at his watch too much. This led to the creation of the Goodwatch, a new bit of hardware that replaces the guts of a Casio calculator watch with a hex editor, ISM-band radio, MSP430 disassembler, and of course an RPN calculator.

[Travis] has already introduced the GoodWatch to the world. We took a look back in December but haven’t heard anything since. His talk at Shmoocon 2018 put a little more light on how this project came to be.

The key bit of hardware in the Goodwatch is the CC430 from TI, an honestly astonishing little microcontroller that includes an LCD driver, a 16-bit MSP430 microcontroller, ADC, a surprising amount of Flash and RAM, and of course a CC1101 radio capable of transmitting in the usual ISM bands. This chip is already found in a few popular projects including the Faraday Open Source digital radio, but the real draw here is the incredible intersection of a peripheral set, low power consumption, and radio.

So, how do you clone a tiny PCB from a calculator watch? The mechanical design of this project was actually the easiest and is decidedly un-clever — just grab some calipers and draw something in a CAD package. Decoding the pinout for the LCD is quite a bit more complicated.

These LCDs have four common pins and more than two dozen segment pins. After figuring out the common pins, [Travis] didn’t really want to open up the watch dozens of times to figure out the LCD, so he simply wrote a bit of code to light up a pixel and clear a pixel. Yes, it still requires a pixel ‘map’ for each pin combination, but thanks to the MSP430’s nifty memory mapped I/O, this code is very simple and very useful once the map is complete.

Right now, [Travis] has a real, working calculator watch PCB that drops right into the Casio CA-53W watch body that nearly anyone can build for themselves. There are some caveats — the radio doesn’t work with the black wristbands because of the oxide layer, and these are miniscule QFN and 0201 components — but this is a proper RPN calculator watch that’s also a radio transmitter. It doesn’t get better than that.

15 thoughts on “Shmoocon: Advanced Low Power Techniques And A Watch

    1. I think it got pulled off the market just as it was it was beginning to take off.
      I was subscribed to a TI newsletter that would inform us as new watches became available, and then silence…
      I haven’t looked at TI since.

        1. I actually have one of these, and it’s a pretty neat little package. I mostly played with it as a diy fitbit, and it was pretty cool. I briefly played with using it as a presentation remote, and then as a mouse. Some guy actually got it to use the accelerometer to detect snapping, and trigger events that way.

  1. “The key bit of hardware in the Goodwatch is the CC430 from TI, an honestly astonishing little microcontroller that includes an LCD driver, a 16-bit MSP430 microcontroller, ADC, a surprising amount of Flash and RAM, and of course a CC1101 radio capable of transmitting in the usual ISM bands.”

    What? No kitchen sink?

  2. Finally somebody that shares my opinion of scrum. My company promotes scrum while also hosting a class “The Five Choices: The Path to Extraordinary Productivity” which from reading the description, one step is not to sweat the small stuff. Opposite of scrum.

    1. I’m not a total fanboi for Agile, but when the project is iterative, and Agile is done right… it flies. Of course a lot of companies don’t do it right (one idiot supervisor when asked to suggest the length of the sprint, said “one month” [facepalm]). Scrum should be a quick standup meeting, 5 min max. if anyone has the inclination to look at their watch, the meeting is too long or the pace is off. The single best reason for daily scrums is to surface any issues that are blockers. Not the small stuff. /sermon

      … and that is one sweet watch.

      1. Dangit, accidentally hit the report button there. My bad. :(

        Anyway, yes. People who complain about scrum/agile aren’t doing it right. And/or just plain don’t know how to work on a collaborative team.

      2. When I worked for a Japanese company here in the USA we had a short standup meeting each morning. Even though I don’t know the Japanese language, I was expected to attend it. As you said this was “iterative”, for an on going project that needed daily updates about changes/setbacks…

        1. We did it fairly successfully on a team of 5.
          Rapidly changing specs and issues (on a daily basis) made burndown charts pretty useless, but stand ups worked very well, and were usually done in 3-5 mins.

        2. There is no ‘right’ in Agile. Or more to the point: if you’re doing it Agile and get results, you’re using it right. If you’re doing Agile and don’t get results, at least you have a frame which will help you to determine what you need to change to do get results.

          I’ve done Agila a lot, and we had lots of good results. So we must have been doing it right.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s