Monthly Archives: March 2015

Logging Weather Data to the Cloud

In this post I want to report some of the finding from a 4 month experiment with a Spark Core. The core is uploading pressure measurement values into the cloud every five minutes. It then loggs them into a Google Spreadsheet. I use the Spark Temboo library and service after I failed to reliably poll the core from Google.

Anyway the Spreadsheet has now more than 30,000 entries. The chart generation is a bit slow but everything is still running stable to this day. A plot of the 4 month is shown below:


After a measurement is taken the core goes to deep sleep to conserve energy. An STM103 internal HW timer interrupt is used to wake-up in time for the next measurement.

Over the four month I have seen only a few corrupted values. These are most likely transmission errors due to network connectivity issues.

PCB Design Workshop

Last weekend I attended a cool 1 day workshop "Designing a Circuit Board" given by Matt Berggren. Matt is a member of supplyframe San Francisco with many years of experience as a PCB designer and instructor.

The class is positioned as "Learn to Build a PCB from the ground up..." targeting hackers and professionals that want to tip their toes into the water of hardware design. This was the 4th installment of this class that always fills up withing a very short time.

Matt is an engaging presenter. He spent the morning explaining the fundamentals of PCB boards and technology. The class does't assuming an EE degree so Matt is careful to explain the fundamentals and terms relevant for PCB design. In fact he is quite a master in catering to the beginners and more advanced members of his audience.

Here is an overview of the topics Matt covered in the morning:

  • Circuit Board basics and terminology - layers, cores, finishes, objects (pads, vias, components, lands, land patterns, footprints, vias), multilayer vs. single-layer, layer types, etc.
  • Some electrical basics related to boards - dielectrics, copper considerations, current carrying, impedance control, parasitic capacitance (don't freak out, we'll explain all of this)

The afternoon was mostly spent hands-on working with Eagle. Here is what we covered:

  • Build our first schematic + PCB + CAM (simple USB power supply that generates some very basic voltages we can use on the bench to do stuff - very simple USB->LDO->Connector)
  • Looked at Eagle and learn some important Eagle terminology, basics of the menus, command line interface, shortcuts, etc + basic workflow (should prepare you for doing this on your own)

Cudo and thanks to Matt. He runs these classes for free at weekends. His audience's backgrounds are very divers. Some are complete electronic novices and some are pros. Matt masters this challenge by providing a lot of well selected practical technical information with entertaining anecdotes. Great teaching job.