Pocket Multimeter

During robotics season, I carry a multimeter in my backpack and as much as I love the UNI-T meters, weight and size start to matter when you carry something all the time so I wanted a smaller, lighter multimeter that still offered full functionality.  In my car, I keep an old Triplett 2030-C which has served me well over many years; the Aneng AN8203 is a knock-off that can be had for under $10 on AliExpress; both have frequency and duty cycle measurement (important for looking at PWM signals in robotics) along with the standard voltage/resistance/continuity and capacitance…but the Aneng has no current measurement where the Triplett does (however the scale isn’t useful for robotics).

Cheap Ultrabooks

I’m not a big fan of expensive laptops.  Computer equipment depreciates at a terrific rate and portable computers are subject to loss, theft, and damage so I want the least expensive machine that will do the job.  That said, I also want it to be compact, light, fast, and last all day on a charge (i.e. an ultrabook).  This may seem like a tall order, but I have found three solutions that I’m happy with.  All involve hacks:

Toshiba Chromebook 2

For MS Windows: The Toshiba Chromebook 2 Model CB35-C3350 has a Core i3-5015U with 4GB DDR3 and a 13.3″ 1920×1080 IPS display.  It’s meant as a Chromebook, but you can replace the internal SSD with a larger one (necessary for it to be useful and I had a spare 64GB M.2 drive on hand) and thanks to coolstar.org, you can install Windows, turning it into an excellent Windows ultrabook.  The main downsides are limited battery life (4-6 hours) and as I’ve gotten older, I find that 13.3″ screen is a little too small.  However, it is extremely portable, fast, sleek, and can regularly be found on eBay for $250-300.

Acer Cloudbook 14

Ultra-cheap-book: Ubuntu Linux: The Acer One Cloudbook 14 has only 2GB of RAM, a slow 1.6GHz Celeron N3050 processor, 14″ 1366×768 display, 64GB SSD, and 10 (real) hour battery life.  So other than the battery life, this is low-spec.  It’s woefully under-powered for running Windows and slows to a crawl as soon as you start doing anything with it.  Fortunately, it is better spec’d for Linux and once I loaded Ubuntu, it was surprisingly snappy and effective.  My old eyes appreciate the larger screen and the very long battery life makes it a great knock-around machine.  You can’t use it for for much software development: the big IDEs like NetBeans and Eclipse are too much for it, but most other apps run just fine.  It can often be found on eBay for $50-$100 and it’s tough to beat that for a thin, light, all-day laptop that’s practically disposable.

Gallium (Ubuntu) Linux: Last but not least is the Acer CB3-431 which is a 14″ Chromebook with a full HD screen (1920×1080), 4GB of RAM, 32GB eMMC storage and a quad-core Celeron N3160 1.6GHz processor; the case is aluminum and looks pretty snappy – an apple knockoff. This is my current carry machine.

Acer Chromebook 14

You can follow these instructions which use Mr. Chromebox to replace the BIOS and install Gallium OS (a great Ubuntu variant designed for Chromebooks) and turn it into a real linux laptop while keeping ChromeOS as a bootable option.  Because linux is relatively lightweight, even with LibreOffice, Slack, Thunderbird, Wine, EmBitz, Eagle, Oracle Java, NetBeans, Tomcat, Arduino, and a full gnu cortex cross development environment installed, I still have used only 50% of the Gallium root partition and it runs fast.  Battery life appears to be > 8 hrs.  Dual-boot has come in handy (it let me recover when a grub update prevented linux from booting) so I recommend it as well as setting the GBB flags as described in the instructions.

Note: if you update grub, it will ask you which partition to use: select the one that covers the entire disk (mmcblk0 I think), not just linux partition (mmcblk0p7).  If you select the wrong one (or both), it will not boot linux.  If you’ve dual-booted, you can reboot to chromeOS (ctrl D at startup screen) and recover.

If you are OK with (or prefer) linux on a light, inexpensive laptop, the Acer CB3-431 is a nice choice and is now the laptop I regularly carry.  It is commonly available “recertified” from vendors like NewEgg for $180 making it not quite disposable, but still very inexpensive. The main downsides are the non-expandable storage (32GB) and the lightweight processor, however I’ve found it extremely usable, all of my apps fit nicely and run at acceptable speeds.  Unfortunately, 1920×1080 is proving tough on my over-50 eyes, even on a 14″ screen.

So I’ve ended up with a Chromebook running Linux, another running Windows, and a Cloudbook running Linux…none of them running what they were intended for…weird!

What I’m still looking for is a thin laptop, less-than 4lb, 15.6″ screen with full HD, Core i5 processor, 8GB of RAM, 128GB+ of SSD, and 8hr+ battery life…for around $300.  Suggestions are welcome!


LG Ultrawide Monitor

There is no such thing as too much monitor…although I think I’ve come close this time.

I bought an LG 34UM69G 34″ ultra-wide monitor for the office from amazon for $215 on Cyber Monday. It has 2560×1080 resolution and is indeed very very wide (21:9 aspect ratio). It’s taking the place of another high-def (QHD) monitor with a more traditional aspect ratio.

When I first saw the box, I worried that it might not fit on my fairly large desk, but I was pleasantly surprised; the ultra-wide monitor fits nicely and looks great. The panel itself had no dead pixels and is very thin with almost no bezel so it looks and feels smaller than the 28″ monitor it is replacing. The base is elegantly designed, feels solid, installs with no tools, and has good adjustments for height and tilt. The internal speakers are good enough that I’ll get the external speakers off my desk; the width helps with the stereo effect.

The full resolution is obtained using the included (but somewhat short) HDMI 1.4 cable and it even works with my ancient Zotac GeForce 210 video card (something that needs to be upgraded soon). Overall, this monitor is a winner and provides a lot of screen real estate without making the text so small that my over-50 eyes have trouble. I don’t think I’d want anything wider or higher resolution (as that would cause text to become too small). Recommended!

Bare Metal STM32 Development on Windows

It’s been a year and a half since I last posted on this and some new tools are available; they work great with STM32L1xx, STM32F1xx, STM32L4xx, etc.

  1. For an integrated IDE, I still like EmBitz
  2. When working from the command line, I still like vim for Windows
  3. For hardware-level debugging (JTAG/SWD), OpenOCD has dramatically improved their support for STM32 and is now better than the Texane STLink IMHO.  You can download windows binaries and the pdf manual or browse the online documentation.  OpenOCD is a GDB server that listens on:
    • port 3333 for a GDB debugger connection for source-level debugging
    • port 4444 for a telnet connection and sophisticated command line interface that lets you use commands like these:

      > stm32l4x unlock 0 (unlock flash bank 0)
      > stm32l4x mass_erase 0 (erase all flash)
      > flash probe 0
      > flash list
      > flash erase_address 0x08000000 0x3000
      > flash write_image myProgram.bin 0x08000000
      > reset halt
      > mdb 0x08000000 32 (dump 32-bytes at start of flash)

    OpenOCD supports many target processors and many hardware interfaces; when you launch OpenOCD, you must pass it two parameters that tell it which hardware interface to use and what target it will be controlling. For example:

    openocd -f interface\stlink-v2.cfg -f target\stm32l4x.cfg

    There are many pre-built configuration files in the interface and target sub-directories wherever you installed openocd. If your interface or target aren’t supported, the configuration files are text and can be easily edited to support your needs.

  4. GNU ARM Embedded Toolchain continues to be the best pre-compiled toolchain and is kept up-to-date.  It includes gdb which can attach easily to an OpenOCD server and let you do source-level debugging from its command-line interface and is well documented and there are many tutorials and cheatsheets.  An example of the CLI use is:
    arm-none-eabi-gdb <myApplication.elf>
    (gdb) target extended-remote localhost:3333
    (gdb) load myApplication.elf (loads image into flash)
    (gdb) file myApplication.elf (to debug an image already in flash)
    (gdb) set remote hardware-watchpoint-limit 6
    (gdb) b main
    (gdb) monitor reset run
    (gdb) c
    (gdb) step (s) or next (n)
    (gdb) i b (info breakpoints)
    (gdb) list [fnName]
    (gdb) interrupt (halt execution)
    (gdb) print <symbolName>
  5. Note: the ‘monitor’ command lets you issue any of the OpenOCD CLI commands from within GDB. For example:
    (gdb) monitor reset halt(reset target and halt target)

  6. Eclipse CDT (especially the standalone version) integrates nicely with gdb and OpenOCD and provides a friendly, smart, graphical source-level debugger.
    • On launch, select the appropriate .elf file for debugging at first dialog
    • Under Window->Preferences->C/C++->Debug->GDB set GDB debugger to arm-none-eabi-gdb (in the appropriate directory – you only need to do this once)
    • In a separate Command window, start OpenOCD with the appropriate interface and target (see above)
    • Under File->Debug Remote Executable: set Binary to the .elf file, Hostname to localhost, Port to 3333, check Attach (you should see gdb connect in the OpenOCD window)
    • In the bottom panel of Eclipse CDT, select the Debugger Console tab (accesses the gdb console)
      • file myProgram.elf (if the firmware is already running on the target)
      • load myProgram.elf (to program the .elf file into the target flash)
      • b main
      • monitor reset run OR
      • monitor reset halt
      • jump Reset_Handler
      • next
      • print myVariable
      • continue
    • From there you can step into/over lines of source code, browse variables and C and assembler source code, view/set/clear breakpoints graphically, and do everything you would expect from a modern debugger.
    • You can read more about it here.

Hybrid Smartwatch

For a long time, I resisted the urge to buy a smartwatch.  Most of them look like you’ve strapped a cellphone to your wrist,  they need to be recharged nightly, they require a button press or a wrist flick just to see the time, many aren’t waterproof, and most of the features aren’t appealing to me due to the small screen.  I tried wearing a fitness band and a regular watch, but wearing two things bugged me.

To the rescue comes the Withings Steel HR, a hybrid of an analog watch, a smart watch, and a fitness band in a nice looking package that is slightly smaller than my old watch.  I’ve been wearing it for several weeks now and I really like it.

The winning features include:

  • Small and light, no bigger than a normal watch
  • Professional appearance
  • Analog hands show time at a glance
  • Fitness dial shows steps at a glance
  • Heartrate monitoring
  • Waterproof
  • Bluetooth link to decent smartphone app
  • 3 week battery life for smart features, longer for watch and steps.
  • Full charge takes about an hour
  • OLED display covers the rest with a single button: date, steps, miles, calories, etc.
  • OLED and gentle vibration also alert you to incoming calls (displays caller) and text messages (displays from whom) and calendar events (displays event title), allowing you to decide whether you need to fish your phone out of your pocket.
  • Note: my eyes and I are over 50 so I was concerned about the size of the text on the small OLED display, but it turned out to be OK.

The watch comes in two sizes, I prefer the smaller (36mm) variant; it includes a black silicone band that is very comfortable and secure, but I am used to a stainless band; fortunately, this watch takes any standard 18mm band so I bought a nice looking replacement on eBay for $10 and it fit perfectly.

It’s not yet officially available in the US, but it will be soon, you can read more about it here.

I still don’t understand why we don’t see old-fashioned LCD or modern eInk smart watches that show the time continuously and run for years on a coin cell, but for whatever reason, we don’t and for now, this is the best solution I’ve found.  Other features I’d like to see in the future:

  • blood pressure monitoring
  • display text of messages (not just who they are from)
  • saphire crystal and/or better protection for the crystal like a standard dive watch

10/24/2017 – A new contender is the Amazfit BiP or the snazzier Amazfit Pace. The BiP has very long battery life (45 days) and the Pace has much less (~5 days) but looks better, both are waterproof, have fitness monitor, GPS, smarter watch features, low price, and always on display. The only down-sides I can see are appearance/size: both are large and considerably less attractive than the Steel HR (the Pace looks better, but the battery life is too short). You can see a video review of the BiP here. When they make one that looks like the Pace but has the battery life of the BiP, I’ll buy one.

Handheld O’Scope

Owon USB scopes are great and I carry one in my robotics bag, but they aren’t ideal for field use because they take too much time and space to setup (laptop, wires, …).  So I purchased a the low-cost JinHan handheld oscilloscope and so far, I’ve been pleasantly surprised.  I bought the JDS2023 on AliExpress for $113 shipped via DHL (quickly); it integrates a 200MS/s dual channel 20MHz digital o’scope with a 5MHz signal generator in a remarkably small, light package.  It has a bright, readable 3.2″ LCD color display and a reasonably intuitive UI (I never needed the manual) although the addition of even a single knob would make the UI better.  It offers all the basic scope functions including automatic frequency and p-p amplitude measurements.  The Auto button does its job well.

JINHAN JDS2023 20MHz 200MSa/s Handheld Oscilloscope with Signal Generator

The company makes several models with a variety of speeds and features such as the JDS2012A that integrate a scope and multimeter.  However, I prefer to keep carrying my UT136B meter which is smaller, easier, more functional (as a meter), and cheap enough that I won’t care when students lose or destroy it.  For advanced diagnostics or impromptu demonstrations, the JDS2023 will replace the Owon USB scope in my robotics bag

EEVBlog does a teardown of the JDS2012a.  The user manual is here.

The scope comes well packaged and includes a single 6100 (ostensibly 100MHz) scope probe, BNC to alligator-clips cable for the signal generator, USB cable, and separate battery charger.  It does not include the required 18650 lithium battery (probably due to air shipping restrictions) or a carrying case…but what do you expect for $113?  Power over the USB cable will run the scope.

I haven’t seen anything close to this level of functionality at this price.  If I need more, I’ll probably step up to the Owon HDS1021M-N or UNI-T UTD1025CL, but they are twice the price, considerably larger, and sans signal generator.

I tested it quickly using a lab-grade RF signal generator and confirmed the 20MHz bandwidth specification; it clearly shows at least 10 points per cycle of the sinewave (validating the 200MS/s specification) and there is no amplitude compression of the 0dBm signal (nominally 0.632vpp into a 50-ohm load – this is unloaded so it correctly shows 2x vpp); the analog front end 3dB compression point is somewhere north of 40MHz.

20MHz Sine Wave

5MHz Sine Wave

3D-Printer: Cube 3

I finally caved and bought a 3D printer: the Cube 3 from 3D Systems and so far I’m pretty happy with it.  See the manual here. The hardware is high quality, it’s easy to use, has dual-extruder jets, and looks pretty sharp.  In some ways it is like an Apple product: a beautiful, but closed eco-system: the main down-sides are that it uses proprietary software and requires proprietary filament cartridges which cost more andsee update below are limited to  PLA and ABS (the most popular material choices); other “cons” are that it isn’t fully enclosed and it doesn’t have a heated base which diminishes its performance with ABS and seems odd for a printer at the $1K price point.

I decided to get this for two reasons:

  1. I’m a beginner at 3D printing and I’d read about folks spending a lot of time getting their printers working in the first place and then keeping them working including constant parts replacements.  The Cube 3 reviews indicate it is good for beginners and I want to focus on learning 3D mechanical design and printing instead of fighting with the tools.
  2. The Cube 3 has been discontinued and is available at fire-sale prices under $200 shipped on eBay including two cartridges.  That’s an amazing price for a well-made printer and unheard of for one with dual-extruders.  At that price, it’s a no-brainer: if I start doing enough 3D printing for the cost of filament to become an issue, I’ll buy another printer and have gotten my money’s worth.

I’ve printed many objects in PLA which have come out nicely.  PLA seems to be the go-to material for 3D printing; it is very strong but brittle, has good dimensional stability while printing (doesn’t shrink much as it cools), and has no smell when you print.  I’ve also printed a couple of objects in ABS and they came out nicely although there was some mild warping at the base (because the platform is not heated). I printed a thin sheet of ABS too and it is remarkably flexible.  There is a slight smell of melting plastic with ABS, but in my basement (big space) it was barely noticeable and certainly not a problem.

Overall, I’m very happy with the purchase and am enjoying 3D printing.

Update: After having used the printer for a while, I still think it is a marvelous piece of engineering, but there are some serious problems with the cartridges.  I don’t mind paying more for the proprietary cartridges – I understand the 3D Systems business model, but  after my 8th cartridge failed, I was no longer sympathetic.  Since 3DSystems has discontinued these printers and abandoned the low-end/hobby market, they should really open the architecture so existing customers can make better use of them.  Fortunately, I have found ways to overcome these issues and will share them below:

  • Adjust the printer ‘z’ gap (the distance between the platform and the print nozzle) periodically.  You do this from the front panel using a provided feeler strip; it doesn’t take long.   You should adjust the gap until the feeler just barely slides beneath both nozzles with some friction between the platform and the lower nozzle.  Having the gap a smidge too wide is better than too tight.  If you are experiencing failure of filament to flow/jammed nozzles, the Z-gap being too small is almost certainly the problem.
  • Don’t be afraid to repair the cartridges.  See how to do it here.  The top cover snaps off; it takes a lot of force, but the cover doesn’t break; 3D Systems advises this in their Advanced Cartridge Reset Guide.  Inside is a spool of filament with a clever latch to keep it from un-spooling when not mounted in the printer and a simple but effective feed mechanism.  Filament passes between two gears that grip the sides and push it forward or backward.  You can manually advance/withdraw the filament if it is broken using a Robertson (square) or Torx T20 screwdriver inserted into the feed mechanism drive (where the printer drives it).  Note that you can only do this when the filament is broken (which happens sometimes); otherwise, keep in mind that the end of the filament is melted into the tip of the nozzle and if you try to withdraw it the filament will break and problems will ensue.
  • Don’t be afraid to repair the nozzle.  The nozzle is a two-piece snap-together assembly that can easily be opened by inserting a screwdriver in the crack near where the nozzle assembly starts and the feed tube stops and prying forward (away from the feed tube).  You can repair a nozzle clogged with PLA by raising the temperature of the nozzle until the PLA softens and the nozzle tip slides off the tube; see here.  Be careful not to pull too hard or you’ll break the plastic feed tube.  If you have one, a hot air workstation (or perhaps a hairdryer) is a great way to heat the nozzle; if not, you can let it heat up in boiling water.  If you do any work with modern electronics, you should have one of these.  I set the hot air to 130-140C and heat the metal nozzle until it slides off the PTFE tube; I hold the nozzle with tweezers or needle nose pliers while it heats applying *very* gentle pressure; it should slide off the tube easily.
  • There are firmware hacks that allow you to use non-proprietary filament; this works, but you use it at your own risk: see Cube Toolbox.  A video showing how to use it is here if needed.
  • I find the cartridges sufficiently unreliable that I no longer use them as intended; I remove the filament spool and put it on an external spool holder.  I leave the cartridge cover off and feed the filament into the bottom of the extruder assembly and I hot-glue the portion of the PTFE sheath that fits into the cartridge edge so that it stays in place even with the cartridge open.
  • Finally, filament absorbs water from the air and becomes brittle and problematic.    This is not a problem specific to this printer, it affects all FDM printers.  Once opened, filament needs to be stored in a sealed airtight container.  To fix old filament, that has already absorbed moisture, I put the filament in a food dehydrator overnight at around 130F.  When filament is not being used, I store it in a ziplock bag with a few desiccant packets which I then put in an airtight container such as an ammo box (available at Sams and Costco).  For storing more filament, I use a bucket with screw-on cover and silica gel kitty litter for desiccant.

I haven’t yet tried it, but someone has made an enhanced feed mechanism for supporting other filament types; see here.  There is an even simpler method that I intend to try here. that uses

If you want to refill a cartridge, there is a filament winder apparatus here with video showing its use here.

Some Cube 3 resources:

  • http://www.print3dforum.com/forumdisplay.php/31-Cube3
  • https://www.thingiverse.com/groups/cube3
  • http://cubifyfans.blogspot.com/
  • http://www.openbuilds.com/threads/tear-down-of-cubify-cube-3-3d-printer-convert-to-reprap.5689/


Orange Pi

I bought two Orange Pi single board linux computers: an OPi One and an OPi PC. Getting up and running took me a lot of time, but once you know how, it’s easy peasy. The main issue with the OPi is lack of documentation, particularly from the manufacturer whose website is often down or slow as molasses.  There are some other sources of information including orange314

I’ll describe what you need in this post so you can have a smooth out-of-box experience. Documentation for these boards is lacking, but there is an extremely active user community and most of the negative reviews and comments you’ll see about the OPi no longer apply. You will need the following:

  • Good 5v/2A power supply with 4mm x 1.7mm DC barrel jack (same as used on Sony PSP)
  • 8GB or larger Class 10 or better microSD card
  • Ethernet cable and connection
  • Recommended: HDMI cable and monitor
  • Recommended: USB keyboard and mouse
  • Optional: USB-to-TTL-Serial adapter

I’ll describe these in more detail below:

POWER SUPPLY: The Orange Pi requires a 5V/2A good quality power supply. The power input is a 4mm x 1.7mm DC barrel jack (same as Sony PSP and many other devices). You cannot power it through a microUSB cable like a Raspberry Pi; you have to power it through the 4.0mm x 1.7mm DC power jack. I made the mistake of buying a really cheap after-market power supply meant for the Sony PSP and had lots of trouble because the power supply was too noisy; others have had similar problems. Get a good power supply like this one from LoveRPi or a microUSB to barrel jack adapter if you want to use a good existing micro-USB 5v/2A supply.

MICRO-SD CARD: There are a zillion Linux (and Android and other OS) distributions for the Orange Pi, but many of them are hard to install or missing important capabilities. I spent a lot of time sorting through them and ultimately installed ARMbian Linux (Debian Jessie Server) using Rufus onto a Samsung EVO 16GB Class 10 micro-SD card. I plugged in the uSD card, Ethernet, HDMI monitor, USB keyboard, and power, and my Pi was up and running (fast)! There was lots of space left over on the 16GB card; even an 8GB card would leave plenty, but try to avoid slow cards (e.g. don’t use Class 6). ARMbian is a great distribution that is pre-configured for the OPi PC; everything worked out of the box; my network connection came right up using DHCP and I could ssh into the OPi.

USER INTERFACE: The intended user interface is an HDMI monitor and a USB keyboard (and mouse if you are installing the desktop/GUI version). If you are technically inclined, the other thing that’s very useful is a USB-to-TTL-serial cable so you can access the serial console. 115200bps, 8, N, 1, Pin 1 on the 3-pin header is ground. Accessing the serial console lets you see what’s happening very early in the boot process; when booting is complete, you can login there as well. A tiny USB serial console is a lot smaller to carry in your laptop bag than a monitor and keyboard.

OTHER USEFUL TOOLS: You may also find SDFormatter useful for erasing/reformatting SD cards.

COOLING: ARMbian runs the CPU pretty cool; it rarely got more than slightly warm to the touch. However as I was experimenting with different linux distributions, some would get the SoC very hot very quickly. Self-adhesive heat sinks are very inexpensive and probably worth adding, at least one on the H3 SoC.

CONNECTING TO PROJECTS: If you plan to connect your OrangePi to some custom electronics, WiringPi has been ported to the OrangePi and I was able to have it blinking LEDs within a couple of minutes. If you need them, instructions are here and for more info see here.  If you follow the steps I mentioned above, you should be up and running quickly. Good luck and have fun!

JavaCV (OpenCV for Java) on Raspberry Pi

The Raspberry Pi has a powerful processor and GPU making it one of the few low cost embedded platforms suitable for machine vision and video processing.  The OpenCV computer vision library is popular for C++ development.

Update 11/25/2017:
Benji found JavaCV too limited in that it used OpenCV 3.0.0 and old/poorly documented ‘C’ APIs where the newer documentation is all focused on C++. He built OpenCV with the Java bindings from source on an RPi3 using the latest Raspbian; you can read about it here

JavaCV uses JavaCPP to automatically construct JNI wrappers around the CPP OpenCV classes.  The port was done by Samuel Audet and you can read about it here.  Good sources of documentation are the OpenCV documentation and the JavaCV wiki.

The Raspbian repositories don’t have up-to-date versions of either OpenCV or JavaCV so you’ll need to install them yourself:

  1. The easy way:
  • Download the 4 pre-compiled binary .jar files here  (source page: here) or from this site: javacv-1.0.jar javacpp-1.0.jar opencv-3.0.0-1.0.jar opencv-3.0.0-1.0-linux-arm.jar
  • To test:
    • put them in a folder such as “./opencv”
    • create this test program:

      import static org.bytedeco.javacpp.opencv_core.*;
      import static org.bytedeco.javacpp.opencv_imgproc.*;
      import static org.bytedeco.javacpp.opencv_imgcodecs.*;

      public class Smoother {
      public static void smooth(String filename) {
      IplImage image = cvLoadImage(filename);
      if (image != null) {
      cvSmooth(image, image);
      cvSaveImage(filename, image);

      public static void main(String[] args) {
      if (args.length > 0) {

    • Compile (note: the binary .jar files were build w/Java 7 so you must target java 7 for your bytecode too):

      javac -source 1.7 -target 1.7 -classpath “./opencv/*” ./Smoother.java

    • Execute on a sample image file; the output will overwrite the file with a smoothed version of the image:

      java -cp opencv/*:. Smoother Rough_piddock_BW.jpg

2. The hard way…build it all from source while wrestling with gobs of dependency issues:

  • OpenCV 3.1 install instructions are here and here.
  • You will need to install many dependencies including maven, ant,  and doxygen.  You can read about the dependencies for JavaCV and JavaCpp by following install instructions here or here


NOOBS on Raspberry Pi

Notes on setting up NOOBS (Debian Linux) on a Raspberry Pi

  1. Download NOOBS linux (offline version) from here and copy all of the files in the .zip to the root of an SD card
  2. Boot the SD card with a monitor and keyboard attached to the Pi
  3. Use the Pi GUI to configure the WiFi network (if desired)
  4. Configure the Pi to use a default IP on the Ethernet interface that’s on the same subnet as the PC auto-IP subnet (169.254.x.y) – I used (‘R’.’P’); this will let you boot the Pi headless, connect it to the Ethernet port of your PC, and ssh into it with no other hardware.  To do this, modify the file /boot/cmdline.txt and add “ip=” to the end of the single long line.  See details here.
  5. Login (default user is ‘pi’ and default password is ‘raspberry’)
  6. sudo apt-get update
  7. sudo apt-get upgrade