Tag: Raspberry Pi

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Computers Lab

Dual Satellite NTP server with Navspark

A friend from NIST recently told me about a Raspberry Pi Stratum-1 NTP server project, and that reminded me of the experiments I did with the Navspark dual GPS+Beidou receiver module. Navspark is a small, Arduino-compatible module that besides GPS can also receive data from China’s Beidou 北斗 satellite navigation system , that is currently being built. I thought it would be fun to build a Beidou-powered Stratum-1 NTP server to see how does it compare to GPS.

Hardware

To have a really good really good, satellite-powered reference clock, I have to have access to a 1-pulse-per-second (1PPS) signal from the receiver. The pure USB-connected receivers don’t really seem to do that yet (looks like plenty of opportunities there!), instead I have to use separate hardware for it.

The Navspark module has a 1PPS pin (GPO3 below), and the only other pin I’ll really need is a serial pin to receive the NMEA stream of the satellite lock data (TXD1 below).

Detailed Navspark pinout with pin functions
Navspark pinout from the User Manual
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Computers

Magic for the Internet of Things: Resin.io

I have my fair share of playing with embedded Linux and Internet of Things projects these days, but the real treat is finding projects occasionally that just blow me away. Through some Hacker News comments I ended up checking out Resin.io, a tool that brings cloud deployment and management to embedded applications. That might simple (boring?), but here’s the workflow in a nutshell:

  1. Start a new application and download an image file for your chosen single board computer (1 of 5 choices at the moment: Raspberry Pi 1 & 2, Parallella, Intel Edison, and BeagleBone Black)
  2. Flash the image onto an SD card, connect the board to the network, and boot it up
  3. The board shows up in the cloud management console, and you get a git repo address
  4. Make an application (Docker, Node.js, etc.), do a git push: voila, your board’s running your app
  5. Flash a few more SD cards, connect the devices to the network, all of them will run your application
  6. Modify the app behaviour through environment variables, either all of them at once, or customize each
  7. Check status, logs, updates, online, and enjoy that things just work!

I cannot emphasise enough how good any service feels that 1) runs by git pushing code, and 2) just works.

SomaStream

To try it all out, I’ve put together a very simple application: SomaStream – the SomaFM internet radio streaming app.

SomaStream device status
SomaStream device status (image uploading)

Grabbed my RaspberryPi that didn’t do much lately, plugged an earphone in it, and started to look for some examples in the docs how to make it play some streaming music. 

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