Author: <span class="vcard">andy</span>

Replace that tennis ball with a talking Raspberry Pi!

Posted on February 1, 2018 by in Raspberry Pi
The challenge is not to hit the ladder while parking

Our garage has a ladder sticking out near where we park our car.  We want to park close to the ladder leaving enough room to walk in front of the car and also allow room behind the car for the garage door to close. A typical solution to this need, and one we’ve used in the past, is to have a tennis ball on a string positioned such that the car window nudges the ball and shakes the string — so you know when to stop.  A great analog solution!  I, however, desired a digital solution that incorporates a Raspberry Pi.

This parking-assist solution doesn’t “speak” to me!

OK, a digital solution should either have a sensor that is tripped by the car or, even better, something that could dynamically measure and show the distance from the car to the ladder.  This would require some way to provide feedback to the driver.   Hmmmm, feedback could be visual or maybe via sound.  Yes,  that’s it!  I could have an R-Pi measure the distance and “talk” to the car driver.  Another project is born 😎

 

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MongoDB 3.0.14 for Raspbian Stretch

Posted on August 26, 2017 by in Raspberry Pi

The main operating system for Raspberry Pi, Raspbian, continues to evolve.  The latest version as of August 2017 is “Raspbian Stretch” — based upon the current stable version of Debian 9.  The previous version was known as “Raspbian Jessie”.  One difference between versions is OpenSSL libraries. OpenSSL is a general purpose cryptography library that provides an open source implementation of the Secure Sockets Layer (SSL).  My previous builds of MongoDB relied on the older library.  As a result, my previous binaries for 3.0.14 and 3.0.9 do not run under Raspbian Stretch.  Given this change as well as other changes to MongoDB source and newer compilers, I could no longer compile MongoDB 3.0.14 with SSL.

After a few source tweaks and use of various compiler flags, I have manged to compile MongoDB core apps and tools.  These binaries do NOT support SSL and only run under Raspian Stretch on a Raspberry Pi 3.  [UPDATE — 2018 Mar 22] I have confirmed that these binaries work on the latest Raspberry Pi 3 Model B+ with the March 2018 version of Raspbian.

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PerAspera-AdAstra.Space

Posted on July 16, 2017 by in Uncategorized

The Planetary SocietyMy wife, Claire, and I have been members of the Planetary Society since its founding in 1980. I was fortunate to be working at The Jet Propulsion Laboritory when Carl Sagen, Bruce Murray and Louis Friedman founded the society. Bill Nye, “The Science Guy” and space advocate, is now CEO.

The society’s mission has changed only slightly over the years and is now:

to empower the world’s citizens to advance space science and exploration. We advocate for space and planetary science funding in government, inspire and educate people around the world, and develop and fund groundbreaking space science and technology.

So, why this post and why this title? The Planetary Society has offered a year-free domain registration with the Top-level domain (TLD) of “space” to members. Well, I needed to take advantage of that and spread the word about this TLD. Being a big Science Fiction fan, the phrase, “Per aspera ad astra” came to mind. Several variants have already been taken so I had to be a (tiny) bit creative.

Until I think of “better” content and have time to put something together, the URL, PerAspera-AdAstra.space points to this blog.

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MongoDB 3.0.14 binaries for Raspberry Pi 3

Posted on March 18, 2017 by in Uncategorized

[UPDATE: 26 August 2017 – The binaries referenced in this post only work with Raspbian Jessie!  If you have upgraded to Raspbian Stretch on a R-Pi 3 or R-Pi 3B+, get the newer binaries]

The mongoDB documentation at mongodb.com states that 32-bit binaries are deprecated with release 3.2 and will be unavailable in future releases.  The latest version with 32-bit support (i.e. R-Pi with Raspbian) is 3.0.14 as of March, 2017.  I have compiled MongoDB 3.0.14 for Raspberry Pi 2 and 3.  I needed a few tweaks to the build process I used to compile 3.0.9 and associated tools. Use the installation instruction in my previous blog post to install and run MongoDB 3.0.14 on R-Pi.  The only change is to download newer files.  I have compiled MongoDB and Tools with the SSL flag — so the SSL option is available.

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Official MongoDB 3.4 on ODROID-C2 under Ubuntu

Posted on January 5, 2017 by in ODROID

I’m a big fan of MongoDB but contrary to its “humongous” orientation, I like to think small as in ARM-based SBCs like the Raspberry Pi or ODROID-C2 and DBs under a terabyte 😉  You can get a lot of power out of tiny inexpensive computers and USB disk drives!  You can find my blog entries, below, for getting 32-bit MongoDB 3.0 working on R-Pi and 64-bit, MongoDB 3.2 working under ArchLinux ARM on ODROID-C2.

I had seen MongoDB community requests for a 64-bit ARM version and even a mention that there was “official experimental” development going on – including the efficient WiredTiger storage engine.  I recently perused the MongoDB Community Edition documentation for version 3.4 and saw a download option for “Ubuntu 16.04 Linux 64-bit ARM 64” on the MongoDB Download Center.  Ubuntu 16.04 is the default Linux supplied with the ODROID-C2 🙂  You can purchase a bare ODROID-C2 for US$40 at Hardkernel. Micro SD card or EMMC module with preinstalled Ubuntu Linux is extra.

Click more for installation instructions.

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CouchDB 2.0 on Raspberry Pi

Posted on December 22, 2016 by in Raspberry Pi

The Apache Software Foundation has released CouchDB version 2.0.  CouchDB 2.0, is a “distributed” version of CouchDB, a mature NoSQL, document-oriented data-store that is accessable via a RESTful JSON API. Developers can take advantage of CouchDB’s offline capability and reliable data sync for web, mobile and IoT apps at (any) scale.

[NOTE: September 2017 — CouchDB 2.1 and Raspbian Stretch have been released.  Check out updated instructions in this blog post]

Current Raspbian (November 2016) can “apt-get install” version 1.4 and I have previously written about getting CouchDB 1.6 running on the R-Pi.  I have now installed version 2.0.0 on an R-Pi 3 and am sharing the process.  It is pretty straightforward to get CouchDB 2.0 running on the R-Pi. It takes a combination of the R-Pi specific 1.6 install and the “generic linux” 2.0 install to get things running.

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R-Pi Clock Radio – Zeroed!

Posted on September 10, 2016 by in Raspberry Pi

clock_radio_20160909_smallWe had a really old alarm clock in our bedroom.  Really old.  The LED number segments, which were a nice dim red in color, had been dying at the rate of 1 segment a year and it was getting hard to read the time.  My wife finally had enough of my “I’ll get a new one real soon” excuse and bought a new big, bright, blue LED clock to replace the old clock.  It was blue … and *really* bright … even in its dim-mode 🙁  It had to go!

My converted 1942 Crosley Radio was collecting dust on my workbench.  I had finally received a Raspberry Pi Zero and Zero4U USB hub to play with but was already lusting after the new R-Pi Zero with camera port.  I recently upgraded the audio-output on my Mac from an old USB HiFiMan Express DAC to  a Schiit Modi DAC.   Hmmmmm, seemed like I had the ingredients to make a BIG clock “radio” with alarm(s) and great stereo audio?

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MongoDB 3.2.10 running under Arch Linux ARM 64 bit

Posted on May 27, 2016 by in ODROID

ODROID C2 SBC

I use MongoDB as my database of choice as you can tell by my blog entries.  Under current Raspberry Pi OSs, MongoDB is limited by 32 bit binaries. Databases are restricted to 2GB.

The Raspberry Pi 3 sports an ARMv7 processor that supports 64 bits.  At this time (May 2016) there is no official OS support for 64 bits.  Raspbian and Arch Linux are only available with 32 bit support.  I expect that we WILL see 64 bit support sometime in the future 😉

While waiting, I looked around and found MongoDB 3.2.6 3.2.10 in the Arch Linux ARM aarch64 package repository.  I also found out that the ODROID C2 single board computer supports aarch64.  This SBC costs $40 and has better specs (for my DB purposes) than the R-Pi 3.  It has a 4-core ARMv8 processor running at 2GHz, 2GB of RAM and gigabit ethernet. It also supports WAY fast eMMC Flash storage in addition to Micro SD.  Android and Ubuntu are the officially supported OSs but Arch Linux ARM (64 bit) can be installed as well.

[UPDATE: 23 Mar 2017] If you prefer to use the default Ubuntu Linux for ODROID C2 as opposed to Arch, you can now install official MongoDB 3.4.  See this blog post.

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Using Python with MongoDB on Raspberry Pi 2 & 3

Posted on March 3, 2016 by in Raspberry Pi

mongodb plus pythonI’ve written about getting MongoDB running on the Raspberry Pi 2. View my other posts where you can get binaries (3.0.9) or learn how to compile from scratch (3.0.7). The mongo shell works great but you may want/need to code in Python, especially for device control or data logging, etc.

PyMongo is a Python distribution containing tools for working with MongoDB, and is the recommended way to work with MongoDB from Python. You can either use Python 2 or Python 3. Python 3 did not come on the minimal Raspbian Jessie image but can be installed using “sudo apt-get install python3”.

To install the appropriate PyMongo for MongoDB 3.0.x you can do the following from the command line. Note you could use “python3” where I use “python”, depending on your preference. I normally use the default Python 2.7.

Instructions after the break: (more…)

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MongoDB 3.0.9 binaries for Raspberry Pi 2 & 3 (Jessie)

Posted on January 30, 2016 by in Raspberry Pi

I’ve received feedback that some folks are having problems compiling MongoDB 3.0.7 per my instructions AND it takes a long time 😉

MongoDB 3.0.9 just became available but needs quite a few changes to source in order to compile on the Raspberry Pi.  I worked through MongoDB build scripts for ARCH ARM Linux and managed to “translate” for Raspbian (Jessie) Linux on the R-Pi 2.  Rather than creating patch files and writing instructions for building from source, I am providing my compiled binaries.  PLEASE do not post links to my binaries!  Feel free to download for personal use from this site.

[NOTE: I have compiled version 3.0.14 and created binaries for Raspbian Jessie for the R-Pi 2 & 3. NEW: I have also created 3.0.14 binaries for the R-Pi 3 running Raspbian Stretch that will also work on the new R-Pi 3B+.  I have confirmed that the instructions in this blog entry work with the new binaries.]

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