Raspberry Pi 2 vs. 1 GPIO Benchmark

Raspberry Pi 2 GPIO Benchmark

It’s battle time! Some of you may have heard that Raspberry Pi 2 is out with more punch than ever. Just how much more? Well, apt-get dist-upgrade went about 5 times faster with the new Pi. With 1 GB of RAM and four cores, this will definitely be a boost for my home SSH box ergonomics over the previous version.

But what about hacking? There has been a lot of interest in getting GPIO benchmarks for the Pi 2 similar to my earlier Raspberry Pi GPIO benchmark. Well here it is! Please refer to the earlier article for source code and nice screenshots of square waves, as I’ll concentrate on the performance difference only here. You can also get the code from Github:

https://github.com/jokkebk/rpi-gpio-benchmark

Summary of results

All the Pi 1 benchmarks were ran 14th and 15th February 2015 using latest versions of the libraries as stated in my updated benchmark post. Pi 2 benchmarks were all run 25th and 26th March 2015 with the latest versions. If you get significantly different results at a later date, please let me know and I’ll update the table!

Language Library Pi 1 Pi 2 Change
Shell /proc/mem access 2.8 kHz 7.0 kHz 2,5x
Shell / wiringPi WiringPi gpio utility 40 Hz 95 Hz 2,4x
Python RPi.GPIO 70 kHz 243 kHz 2,5x
Python wiringpi2 bindings 28 kHz 103 kHz 3,7x
Ruby wiringpi bindings 21 kHz N/A 3,7x
C Native library 22 MHz 41.7 MHz 1,9x
C BCM2835 5.4 MHz 7.2 MHz 1,3x
C WiringPi normal GPIO wiringPiSetup() 4.1 MHz 9.3 MHz 2,3x
C WiringPi GPIO wiringPiSetupGpio() 4.6 MHz 9.4 MHz 2x
C WiringPi sys wiringPiSetupSys() 120 kHz 185 kHz 1.5x
Perl BCM2835 48 kHz 154 kHz 3.2x

Continue reading Raspberry Pi 2 vs. 1 GPIO Benchmark

Topre Realforce 88UB – A Happier Hacking Keyboard

Topre Realforce 88UB review

This is my review of the Topre Realforce 88UB mechanical keyboard with evenly weighted 45g switches and UK layout. This is the ISO layout sister model of the Topre Realforce 87U (87UB / 87UW) so everything in this review will apply for that model, except a few layout details regarding the extra keys. Before diving into details, a short background of my previous journey:

Two years ago I got really interested in high quality mechanical keyboards. After all, the keyboard is the instrument I use several hours every day, so if I am spending close to 2000€ on a workstation and display, why should I compromise with a cheap 30€ keyboard, especially since the keyboard will likely last several workstation lifespans?

After heavy research I settled on Happy Hacking Keyboard 2 Professional due to its compact “hacker” layout which seemed great for vim, and Topre key switches, which many consider to have the very best tactile feel. See my review of the HHKB2 keyboard for details.

However, in two years of typing with the HHKB, I never fully learned to use function key bindings for cursor keys and Home/End fluently. Coding with Vim somewhat alleviated the problem, but every time with a command prompt or a shell this nagged me. Also, playing games required a separate keyboard, as most games make use of function keys, and many make use of both WASD and cursor keys. It was time for something else. Something better.

Topre Realforce 88UB – Best of both worlds?

After my experience with HHKB, I had the critical components for my dream keyboard well thought out:

  1. Tenkeyless model with dedicated cursor and function keys. I’ve also used CM Quickfire TK and I can say from experience it is a terrible idea.
  2. ISO layout, so I get the \ and | right next to my right pinky, and an additional key next to z to get < and > in Finnish keyboard layout (it doubles as another \| in US layout)
  3. Topre switches for the ultimate typing comfort. Having used rubber dome, scissor mechanisms and Cherry MX blues, and trying out reds, blacks and browns, there really is no competitor. Buckling spring is just too heavy and noisy for my taste.

The items 1 and 2 are quite easy, but the third one essentially meant that the Topre Realforce line would be the primary candidate to fill all these needs. I’ve used The Keyboard Company before and they have a superb selection of Topre models, so I quickly zoomed in on the black 88-key model with UK layout:

Topre Realforce 88UB UK layout
Continue reading Topre Realforce 88UB – A Happier Hacking Keyboard

Mounting / Fixing Raspbian SD Card from Raspberry Pi

Shut down my Pi today and thought to make a copy of files in its SD card. This is what mount /dev/sdf2 /mnt had to say:

mount: wrong fs type, bad option, bad superblock on /dev/sdf2,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

Great. After trying parted and fsck, it became apparent that for some reason, the root partition is marked as being 1 block longer than the physical card. Must be a bug with Raspbian partition expansion or something.

Thankfully, I found this gold nugget which suggested using resize2fs to fix it. Turns out I had to run e2fsck first (and say “y” a couple of times):

sudo e2fsck /dev/sdf2
sudo resize2fs /dev/sdf2
mount /dev/sdf2 /mnt

Voilá! Fully functioning filesystem again.

Raspberry Pi GPIO Benchmark Updated!

main2015

The new Raspberry Pi model 2 is out and the Pi world seems more popular than ever. My 2012 benchmark of different RaspPi GPIO access methods has been getting a lot of hits, so I thought to revisit it, and have now updated all the benchmarks with latest versions of firmware and GPIO libraries. I’ve also upgraded my oscilloscope to PicoScope 5444B, so the scope bandwith limitations I had earlier are now gone. :)

Because the benchmark has been linked from many other sites, I’ve just updated the old post to keep links pointing to right places.

Read the updated Raspberry Pi GPIO Speed Benchmark!

Picoscope Beta for Linux

Picoscope for Linux

Tux logo by Larry Ewing, Simon Budig, Anja Gerwinski

I’ve been a big fan of Picotech’s USB connected PC oscilloscopes ever since I purchased my first PicoScope 2204 almost two years ago. I liked the compact form factor on my desk a lot, and the powerful Picoscope software for Windows – Picotech makes only one version of this software so you get the same functionality with a £159 ($260) 2204 scope as a £5,995 ($9,900) PicoScope 6407 user would – although of course the scope features would be wildly different.

Now Picoscope is a great piece of Windows software and as I generally use Win7 to avoid reboots every time I want to use Photoshop or play a session of Mass Effect, it’s been perfect for me. However, quite a few of electronics enthusiasts are also big advocates of open software movement, and while Picotech has had drivers and SDK for Linux for a while to implement things like my realtime composite decoder, the fact that there is no Linux version of the oscilloscope software has been unfortunate. So when I noticed in the latest Picotech newsletter that there is now a beta of Picoscope for Linux, I knew I had to take it for a spin.

Installing Picoscope on Linux Mint 15

Picotech’s installation process is built on apt packaging system, so a Debian-based Linux distro is the easiest installation target. This includes the wildly popular Ubuntu and Linux Mint distros, which means mainstream Linux users are well catered to. In Picotech forums, the beta thread had at least one user who extracted necessary stuff from the .deb packages and installed the software for Fedora, too.

In Debian-based Mint, the installation went without any hiccups just by following the instructions at Picotech’s Linux Drivers page. Note that sudo apt-get install picoscope also installs all drivers so you don’t need to install your model-specific driver separately. Essentially the installation is just:

sudo echo deb http://labs.picotech.com/debian picoscope main >> /etc/apt/sources.list
wget -O - http://labs.picotech.com/debian/dists/picoscope/Release.gpg.key | sudo apt-key add -
sudo apt-get update
sudo apt-get install picoscope

Continue reading Picoscope Beta for Linux

Unzip Library for C

Christmas holidays are a wonderful time to invent new projects. I decided I’d do some desktop coding for a change, and try to code an optimized image viewer for my old zipped pocket camera photos. First task of course was to read a zip file.

To my surprise, there wasn’t a “GNU standard library” available for this task like there is zlib for general compression, or libjpeg and libpng for images. Best match for my simple needs seemed to be Minizip, but at 7378 lines of code, and 2125 for just unzip.c (utilizing zlib so basically just file handling), I was not convinced, especially because I knew I had some very specific requirements to cater for (namely uncompressing all JPEGs to memory for fast rendering and thumbnail generation).

Zip File Structure – The Essentials

The ZIP file format turned out to be surprisingly simple, especially since I decided I would be sticking to bare essentials and skipping zip64 support, encryption, multifile zips, and all other compression methods than “store” (no compression) and “deflate” (easily decompressed with zlib, see below). Even with barebones setup, my zip routines would handle about 99.9 % of zips out there just fine.

Drawing on excellent ZIP format documentation from InfoZip’s latest appnote, the file structure I needed to parse seemed to have the following structure:

  • Local file header 1
  • File data 1
  • Data descriptor 1
  • Local file header N
  • File data N
  • Data descriptor N
  • … optional decryption / extra stuff …
  • Central directory
  • … zip64-specific extra stuff …
  • End of central directory record

Continue reading Unzip Library for C

HHKB Professional 2 Keyboard Review

HHKB Professional 2

The keyboard is something that I use daily, and whether I’m writing e-mails or coding, I’ll likely do several hours of typing a day. Last summer when I switched to US layout in coding and started using Vim, I started thinking that maybe I should upgrade my seven year old Logitech keyboard to something hopefully better. And when I get such a project, I did what I always do: Went totally overkill with research and ended up spending a few hundred euros once I had made up my mind on the “most optimal choice” for me. :)

Update: If you’re interested in this review, you might want to check out my continuation with the Topre Realforce 88UB.

Keyboards: 101

My worldview after 2000 was essentially that laptop type flat keyboards are the way of the future, and keyboard choice mainly depends on whether you buy a Logitech or Microsoft one, and do you get the top of the line model or an OEM version for 15 euros. Enter Geekhack and some interesting discussions at Stack exchange, and it quickly became apparent that there is more to it.

First choice one needs to make is the layout of the keyboard. Kinesis makes some weird looking ones that some people swear by, and there are matrix-type layouts, I decided I would continue to risk carpal tunnel syndrome with a “normal” layout for the time being, as I don’t want to optimize my brain for a keyboard type that would only be available at home.
Continue reading HHKB Professional 2 Keyboard Review

Vim Colorschemes with Putty aka. GUI vs. xterm-color256

256 color Vim in Putty

I made a big step in coding geekdom this summer by upgrading the most low-level part of my programming workflow. It started when I got frustrated with Mac keyboard shortcuts on Scandinavian keyboard layout (they Just Don’t Work for most apps), and switched to US layout in coding. Once I made that transition, I started thinking that maybe I could improve my coding speed a bit more, and see what all the fuzz is about Vim.

The greatness of Vim in coding comes from the fact that Vim has separate modes for editing text, and navigating around. While not editing, all normal keys become powerful commands, and you can do text manipulation like duplicating lines, indenting sections etc. without ever leaving this “normal mode”.

Well, Vim is great, but an additional bonus to its power is the fact that almost every *nix system has it preinstalled. So even if I’m not on my own computer, I can just launch an SSH client and use Vim to edit the piece of code I’m working on. No need to compromise. Except color schemes, which I just couldn’t get working over Putty. Today I solved that puzzle after one and half hours of googling, and thought to share the findings, maybe someone will find this the next time they face the problem.
Continue reading Vim Colorschemes with Putty aka. GUI vs. xterm-color256

A bit of audio tinkering

I’ve been quite busy the last two weekends, first on a weekend holiday trip to Tallinn, Estonia, and then playing in the Helsinki Casual go tournament which successfully took most of my time last weekend. This has somewhat delayed my continuation to the composite video decoder project.

However, I haven’t been resting on my laurels completely even electronics-wise. My trip to Tallinn had one good by-product, namely new Audiotechnica ATH-M50 headphones. They are a marked improvement over my previous HD-500 Sennheisers, and got me inspired to getting a headphone amp, a tube-based Little Dot mkIII to be more exact. The 32 ohm ATHs don’t necessarily need an amp, but now I’ll at least be prepared if I ever end up getting something like HD-650s.

While researching for a proper USB DAC I came across an amazing audio blog by NwAvGuy. Compared to a lot of “audiophile” coverage he seems to have a solid engineering perspective to audio issues, and he has put an amazing effort to long articles that deal with many issues that surround headphone amp gear.

In addition to great scientific info, NwAvGuy has also designed a USB DAC called ODAC, which I ordered from Head’n’Hifi (they conveniently ship inside EU so no customs). And while I was at it, I couldn’t resist getting a DIY version of NwAvGuy’s O2 headphone amplifier. Read on for my experiences on building it and pitting it against the Little Dot mkIII tube amp.
Continue reading A bit of audio tinkering