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Orange Pi Zero – $20 single-board computer

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The single-board computer space is getting crowded, and Orange Pi is yet another fruit-flavored Raspberry Pi clone, from China based Shenzhen Xunlong Software. The Orange Pi Zero is their smallest model, but still packs a H2 Quad-core Cortex-A7 ARM CPU; Mali 400MP2 GPU; 512 MB RAM; 100Mb/s ethernet RJ45; and 802.11 b/g/n wifi. The basic board also gives you one USB 2.0 port, while the add-on board gives two more, plus audio, IR. It also has additional GPIO pins, similar to the RPi. Both boards, and a case can be had for $20 from DealExtreme. An even smaller case, containing only the main board is also available.

Compared to the RPi, this board is almost half the size, and half the price, but still includes wifi. The only downside is that there is no HDMI, and TV composite video out is complicated. Even with a wide offering, Shenzhen Xunlong Software is far behind the Raspberry Pi Foundation when it comes to mind-share and community support. That shows in details like the OS distribution download page, where none of the links from product page where satisfactory: Most where old, and others didn’t work at all.

Instead, the Armbian based distributions worked well. Both the Ubuntu and Debian images booted without problems. They both connect to the wired network port with SSH enabled. At first login as root, the password is 1234, but you are immediately prompted to change it.

Given it’s very small footprint, and power (micro USB) as the only required cable, it could easily be hidden or even hide in plain-sight among the usual cable clutter under any office desk. It’d make an excellent spy device, and could be used to listen in on conversations or network traffic. Or conversely, watch out for inconspicuous small boxes around the house or office.

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Asus Thinker Board

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Asus recently released their single board computer “Thinker Board”, modeled on the same form-factor and pin layout as the Raspberry Pi 2 and 3, and at the same price point. It comes with some interesting upgrades over the RPi 3: 2 GB RAM (over 1 GB); 1.8 GHz quad core (over 1.2 GHz quad) dedicated Realtek 1 Gb/s Ethernet; Realtek audio codec; and support for 4k HDMI out. It could make both a good media player platform, as well as a usable desktop box.

In their early review, Hackaday laments the lack of website and community. The former has since been addressed, and Asus’ official site is actually rather slick fun and informative, and includes a Debian based OS ISO and other downloads. They have also put up a Facebook page, but it’s mostly linked product reviews and blog post for now.

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Raspberry Pi headless install

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The minimal “lite” image of Debian 8 (Jessie) is an excellent choice for a headless Raspberry Pi. After downloading to the SD card, these notes from Dmytro Bobkov covers the basic initial setup, while wifi setup from the command line is explained here. More details on CLI wifi on Debian in a previous post here.

If there is no screen or keyboard available, the SD card have to be prepared before the initial boot. Mainly to make sure SSH is running, so you can log in. This discussion covers the topic. However, if things are not working at once, a few debug statements can help. E.g., add as needed in the config file (change the IP as needed to your laptop or machine):

echo "$_IP" | nc 10100

echo "ssh has started" | nc 10100

On the other end, receive the messages by:

while true; do nc -l 10100; done

Finally, you might want to add a few extra packages, based on what you want to use the device for. These might come in handy:

apt-get update
apt-get upgrade

apt-get install htop itop atop git tig tree autossh nmap rsync lynx links emacs

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Raspberry Pi 3 with Wifi and Bluetooth on sale now for $35

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The Raspberry Pi Foundation is not holding back. Since the original Raspberry Pi B launched four years ago, there has been a steady stream of new devices and upgrades: The much improved Raspberry Pi 2 came out two years ago, and it was just before Christmas that the tiny form-factor Pi Zero launched. Today, they’ve announced another upgrade in the form of Raspberry Pi 3 B, also selling for $35.

Apart from an upgrade to a 1.2GHz 64-bit quad-core ARM Cortex-A53 CPU, the most exiting news is the integrated 802.11n wireless LAN and Bluetooth 4.1. Ideally, it means that no other external devices are needed, assuming that a Bluetooth keyboard works (sometimes they can be flaky).

This will likely be a hit, so expect to wait for some time for stocks to fill up with the different retailers. And of course, the stated price might not be obtainable if buying locally.

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Banana Pro

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The Banana Pro from Lemaker is another credit card sized Single Board Computer. The Raspberry Pi is still leading that space with more than five million units sold, but it’s starting to get crowded. Banana Pro is probably one of the boards which comes closest to the Raspberry Pi, and indeed, their first version was called Banana Pi. This is from China, where imitating is a compliment.

However, except for its size, the Banana Pro is a very different computer. It has 1 GHz dual core Cortex ARM 7 CPU and comes with 1 GB of DD3 RAM, embedded Wifi, IR receiver, and maybe the best, a full speed SATA 2.0 connector. The price is similar though, at about €45 from Reichelt in Germany.

Compared to the original Raspberry Pi, it’s actually a very usable computer for day-to-day use. However, the Pi 2 probably evens that out, with a similar CPU and RAM. Just like the Pi, it has a 40 pin header, with 28 GPIO pins. It also has a camera interface, but also a display interface connector.

The distribution Lubuntu comes with Firefox, which runs quite OK. However, graphics acceleration is missing, and that is noticeable. The Lubuntu install detected and used the Wifi and IR receiver out of the box. It so happened that the volume button on my stereo remote was mapped to “CALC”, so the calculator application pops up. Should be great for XBMC / Kodi. An XBMC Debian based distribution is available, called LeMedia. It claims to support hardware graphics acceleration.

There are many distributions available. Another interesting and obvious one would be the Open Media Vault, which makes it into a Debian based NAS with a good web UI. Here the SATA port comes in handy.

Below are front and back pictures, which should be pretty self explanatory (if you click to get a large picture and zoom). All connectors are described. Also notice the Wifi antenna to the left on the last picture, below the micro SD card.

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Proto boards and microcontrollers – an overview

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MAKE magazine has a nice write-up of several of the popular micro controllers, prototyping and hobby boards out there. 36 of them in total. Of course, that covers only a fraction of all the brands, models and variations. That list runs much much longer.

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chroot to ARM

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chroot allows you to “run a command or interactive shell with special root directory”, as the man page says. However, it is assumed that the second level root directory is built for the same CPU architecture. This causes a problem if you want to chroot into an ARM based image, for the Raspberry Pi, let’s say. qemu-arm-static, some “voodoo” and several tricks come to the rescue. The process is documented well at Sentry’s Tech Blog, and the original seems to be by Darrin Hodges.

After downloading and unzipping the image, it has to be mounted. There are a few ways to go about this, but I found the easiest was to use plain old mount with an offset. The typical RPi image file is a full disk image, as opposed to a single partition or ISO though. We are after the second partition, which in our case starts at sector 122880. (See this discussion for how to find the correct starting sector using fdisk).

mkdir /mnt/rpi
mount -o loop,offset=$(( 512 * 122880 )) 2014-01-07-wheezy-raspbian.img /mnt/rpi

Next we’ll copy a statically built QEMU binary for ARM to the mounted image. You might need to install QEMU on the host system first. Furthermore, we need to mount or bind the special system directories from the host to the chroot.

apt-get install qemu-user-static
cp /usr/bin/qemu-arm-static /mnt/rpi/usr/bin/

mount -o bind /dev /mnt/rpi/dev
mount -o bind /proc /mnt/rpi/proc
mount -o bind /sys /mnt/rpi/sys

Next comes the magic. This registers the ARM executable format with the QEMU static binary. Thus, the path to qemu-arm-static has to match where it is located on the host and slave systems (as far as I understand).

echo ':arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-arm-static:' > /proc/sys/fs/binfmt_misc/register

Finally, it’s time for the moment of truth:

chroot /mnt/rpi

uname -a
Linux hrb 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 armv7l GNU/Linux

In some cases, the error “qemu: uncaught target signal 4 (Illegal instruction) – core dumped” occurs. User kinsa notes here that the lines of the file (i.e. on the slave, /mnt/rpi/etc/ has to be commented out (with a # in front).

Congratulations, you now have an ARM based chroot. What to do with it? Maybe install a few “missing” packages before copying over to one or more SD cards, set up the users, modify passwords, etc. Or take advantage of the CPU and memory of the host system or compile from source.

apt-get install htop tree ipython ipython3 gnuplot

As a final note, when done, you want to clean up the mount points.

umount /mnt/rpi/dev
umount /mnt/rpi/proc
umount /mnt/rpi/sys
umount /mnt/rpi

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VGA adapter for the Raspberry Pi

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Just tested a HDMI to VGA adapter for the RPi with my old CRT 1024×768 monitor. It works great! This was the HD2V04 HDMI to VGA + 3.5mm Audio Jack Converter Adapter Box from DealExtreme, at $21.70. The VGA port was a bit tight, so I had to make sure it was properly connected. Also, the monitor did not display anything before a cold restart of the Pi. It comes only with a USB power cable, to it means a wall wart or powered USB hub is required. (It should go without saying that you don’t want to power it off the Pi itself).

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Building XBMC on the RPi

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Some notes on building XBMC from source on the Raspberry Pi: I started with the Raspbian 2013-09-25-wheezy image from here. After basic setup, I switched to CLI only, set the GPU memory to 16 MB, logged in over SSH, and started a screen session. A remote session is preferred, since there will be a lot of coping back and forth between the RPi and your desktop.

For the most, I followed these instructions, with a few modifications: First, the boot files to set GPU memory are not there in the Raspbian distribution I had installed. Instead, I used raspi-config to set the memory split. Secondly, the large one-liner apt-get install of all the dev packages (step 4 in the instructions) did not work very well. It gave dependency conflicts with the mesa packages. I found myself splitting up that line into many chunks, which then worked fine. Finally, a few packages were missing, and I had to run configure several times to figure that out. In the end, I also installed these:

apt-get install dh-autoreconf gawk gperf zip ccache

For a successful build, I had to modify the search path of a header file. There are a few ways to go about that, as discussed here. I used this solution:

sudo sed -i 's/#include "vchost_config.h"/#include "linux\/vchost_config.h"/' /usr/include/interface/vmcs_host/vcgencmd.h

That took me as far as a working XBMC setup, however videos are not playing. With MPlayer there is no problem, but XBMC just gives a black screen. I will have to investigate further.

There’s a similar set of instructions here.

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WiFi adapters for the Raspberry Pi

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A few months back I bought a couple of cheap USB WiFi adapters from DealExtreme. Today I finally got around to try them on the Raspberry Pi. Of the three adapters, two works both on a Fedora 17 64 bits based desktop as well as on the RPi. Notice that they both seem to contain the same chip, and indeed reports the same vendor and product ID. The last, the EDUP device, does detect available WiFi networks, but usually does not establish a connection (the very last time I tried, it suddenly did). I suspect it might be a USB power issue, since it also “crashed” the USB hub on the desktop, causing the keyboard and mouse to temporarily disconnect. Here are some notes which might be related. Of the three, the one with antenna is fastest at establishing the connection, but the other small adapter also gives good transfer speed; around 3.6 Mb/s seen today, but I expect it can go faster.

For other devices supported by the RPi, see the the Embedded Linux WiFi page, and also Element 14′s WiFi testing page.

Product Description USB kernel info NetworkManger info Fedora 17 x86_64 Raspbian “wheezy” Comment
USB 2.0 2.4GHz 802.11b/g/n 150Mbps WiFi/WLAN Wireless Network Adapter USB 2.0 2.4GHz 802.11b/g/n 150Mbps WiFi/WLAN Wireless Network Adapter idVendor=148f, idProduct=5370
Product: 802.11 n WLAN
Manufacturer: Ralink
SerialNumber: 1.0
driver: ‘rt2800usb’ OK OK Works “Plug & Play”.
Connection is established quickly.
Mini USB 2.4GHz 150Mbps 802.11b/g/n WiFi Wireless Network Card Adapter - Black Mini USB 2.4GHz 150Mbps 802.11b/g/n WiFi Wireless Network Card Adapter – Black idVendor=148f, idProduct=5370
Product: 802.11 n WLAN
Manufacturer: Ralink
SerialNumber: 1.0
driver: ‘rt2800usb’ OK OK Works “Plug & Play”.
Somewhat slow at establishing the network connection.
Ultra-Mini Nano USB 2.0 802.11n 150Mbps Wifi/WLAN Wireless Network Adapter Ultra-Mini Nano USB 2.0 802.11n 150Mbps Wifi/WLAN Wireless Network Adapter idVendor=0bda, idProduct=8176
Manufacturer: Retek
driver: ‘rtl8192cu’ Failed.
Hangs USB host.
Works 1 out of 10 times. Crashes the RPi.
Device detected, and sees available WiFi networks, hover does usually not get a connection.
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Arduino adapter shield for the RPi

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The H recently wrote about the AlaMode board which lets you use Arudino compatible shields with the Raspberry Pi. The board connects to the GPIO headers of the RPi, and exposes the familiar pin-set of the Arudino Uno on top. The AlaMode board also contains a real time clock, which it can provide as an add-on to the RPi which as none.

In fact, from the picture, it looks like the board is a full fledged Arudino itself, with an Atmel 328P chip on top. It should mean that you can program it on-board, directly from the RPi.

The board is selling for $45, but is out-of-stock at SeeedStudio.

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Raspberry Pi launched

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The $25/35 Raspberry Pi matchbox computer finally launched today, after much anticipation, impatience and extremely clever marketing. In the last few days, their web servers have been overwhelmed by the people hitting re-fresh to know when the device will go on sale. When it finally did, both distributor web sites melted. The 10k units produced were sold out before lunch.

So, if you’re like me, and did not get a device this time around, you might want to join the support group over at Slashdot. There you will find people crying like kids who missed Santa. If it was kids, that would be one thing, but some of these crying guys actually have jobs. Amazing. Then there was one guy who had missed the weekly, or almost daily articles and didn’t know what this stampede was about. I guess he didn’t get one either.

Well, there will be more of these devices, and then some bugs might even be ironed out.

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Fedora on Raspberry Pi

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Chris Tyler has published a video demonstrating Fedora running on the ARM based Raspberry Pi. This looks very promising, and the Fedora project is working actively to support several ARM based systems.

Here’s general instructions on how to install Fedora from a USB stick, and here’s minimal Xfce based spins. (I am not sure if these instructions apply to Raspberry Pi).

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Raspberry Pi: A €30 Computer

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A few days ago,  Raspberry Pi announced that they had gotten Quake 3 running on their ARM computer. Furthermore, their FAQ estimates the networked model will cost $35 and be released at the end of this year. There is also an interview in the Guardian.

Provisional specification

  • 700MHz ARM11
  • 128MB or 256MB of SDRAM
  • OpenGL ES 2.0
  • 1080p30 H.264 high-profile decode
  • Composite and HDMI video output
  • USB 2.0
  • SD/MMC/SDIO memory card slot
  • General-purpose I/O
  • Optional integrated 2-port USB hub and 10/100 Ethernet controller
  • Open software (Ubuntu, Iceweasel, KOffice, Python)
  • The device is powered by an external AC adapter, and the Model A consumes around 1W at full load.
  • The device should run well off 4xAA cells.

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