Friday, August 30, 2019

Autonomous Raspberry Pi

Solar powered, with a wireless keyboard and touchpad.

Solar powered, with a wireless keyboard and touchpad.


The solar panel

Closed. The keyboard can also fit in the box.

Sunday, April 21, 2019

San Juan Islands, WA

Data logging in San Juan Islands, Washington:

Apr 19-21, San Juan Island

Apr 22, San Juan Island to Orcas Island

Apr 23, Hiking in Orcas Island

Apr 24, Hiking in Orcas Island, Mountain Lake

Apr-25, Back ashore


Data logging was done as explained here, here and here.

Tuesday, March 12, 2019

Easy Low Pass Filter

Instead of implementing a buffer and smooth it, there is a much easier and efficient way to do it. Here is a simple JavaScript implementation. First you define your accumulator function:
 function lowPass(alpha, value, acc) {
   return (value * alpha) + (acc * (1 - alpha));
 }
Then you need to define your APLHA coefficient:
 const ALPHA = 0.015;
Then you can invoke the accumulator with the aplha coefficient on the data to smooth:
 let filteredGustArray = [];
 let acc = 0;
 data.data.forEach(dp => {
   acc = lowPass(ALPHA, dp.gust, acc);
   filteredGustArray.push(acc);
 });
This produces an array containing the smoothed data. Here is a representation of what it looks like, along with the data to smooth (raw data in red, smoothed data in blue):
The demo data are available here. Just run the script with nodejs like
 $ node max.gust.js both > data.csv
This will produce a csv file you can then import into any spreadsheet program, to see the figure above.

Monday, March 11, 2019

Smart TCP Watch, prototype.

TCP, no BlueTooth (and as a result, no Smart Phone) is required. The "watch" can connect directly to the network.
See a first prototype here.
And a short video here.

Monday, November 26, 2018

Saturday, August 25, 2018

Smart watch..., who's smart, who's watching?

I got a Pebble watch a while back, for $100 it did everything I was expecting from it. I came with a cloud/web-based IDE, a really fine piece of work, it was possible to develop and debug applications running on the watch in JavaScript, that was really well done, smart and neat.
Then a while back, Pebble got acquired by Fitbit. And now, the Cloud IDE of Pebble is not available anymore. Than means I cannot develop new apps for my Pebble, even if it is still working just fine.
Why would I buy a new watch (twice as expensive), and re-write all my apps? This is quite frustrating...
In fact, there was something wrong from the beginning.
All those so-called smart watches need a Bluetooth cell-phone to connect to, and from there it will reach other data. Why not a TCP-based protocol from the watch, to bypass the phone? Power consumption? I doubt it.
This is not about accessibility or configuration either, I do it all the time for Raspberry Pis and similar boards, ssh and similar protocols have been here for this kind of remote access, for ages, and for good reasons.
Smart glasses, head-up displays (HUD), smart watches, all those devices are just displays, all they need is to connect to a data bus and display what they mean to (just like an NMEA bus).
I suspect some marketing bullshit behind the scene..., again.

If this kind of TCP watch does not show up soon, I'll build one. Bam!