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Measuring the Raspberry Pi's Current Consumption

nospam@example.com (Chris Tyler) — Wed, 20 Jun 2012 13:00:07 -0400

The Raspberry Pi has a micro-USB jack for power input. This can be used with any recent mobile phone adapter. If you use a two-part adapter, with a plug-in AC-DC converter and a USB A to micro-USB A cable, it's easy to measure the current drawn by the Pi.

To do this, you'll need a USB A male to USB A female extension cord and an ammeter or multimeter with a 1A or 10A range.

1. Remove the outer insulation in the middle of the USB extension cable. Peel back the shielding (silver braid and/or foil) to one side.

2. Cut the 5V supply wire (usually coloured red).

3. Connect your ammeter or multimeter to the cut 5V line.

4. Insert this cable between your AC-DC converter and the USB cable going to your Raspberry Pi.

So, how much current does the Raspberry Pi draw?

It looks like the Pi can draw anywhere from 250 to 500 mA in normal operation, though I did see smaller values in the early stages of startup. When idle, my Pi draws 320-380 mA; with a basic Logitech keyboard and mouse attached and in use, and with the CPU and GPU fairly active, it comes close to 500 mA.

Update: Powering the Pi from a Laptop

The fact that the Pi's current consumption is reliably under 500 mA means that it is actually safe to power from the USB port of another system. This is convenient for developers on the go: for example, I'm in an air-conditioned library escaping the current Toronto heatwave, and have my Pi connected to the back of my laptop with a micro-USB cable for power and a crossover ethernet cable for data.

New Role: Industrial Research Chair - Open Source Technology for Emerging Platforms

nospam@example.com (Chris Tyler) — Thu, 10 May 2012 11:06:59 -0400

On Tuesday, the Natural Sciences and Engineering Research Council (NSERC) announced a number of grant awards at the Polytechnics 2012 conference, including the new Industrial Research Chairs for Colleges (IRCC) grants. I am honoured to be selected as the chairholder for the NSERC Industrial Research Chair for Colleges in Open Source Technology for Emerging Platforms in the Centre for Development of Open Technology at Seneca College.

This five-year renewable applied research grant enables me to continue and expand upon the work that I have been doing, along with a talented team of research assistants, with Fedora ARM and related projects. My goal is to bring the wealth of open source software currently available for x86 PCs and servers to emerging ARM based general-purpose computers. Although ARM architecture chips are the most popular CPUs made (more ARM chips shipped last year than there are people on this planet), most of these went into dedicated devices, and ARM chips are just starting to appear in general purpose computers. In order to make the transition to general-purpose ARM systems viable, industry-standard software stacks are needed. Fedora is a perfect fit for this purpose, because it encompasses both a large collection of cutting-edge open source software and a vibrant community, and it feeds many downstream distributions and projects.

My work in this new role will start with an expansion of existing work, including operating the Fedora ARM Koji buildsystem and improving the Raspberry Pi Fedora Remix, but I will additionally be focusing on Fedora on ARM server-class systems. In future phases, this will encompass working with the Fedora ARM project to promote ARM to primary architecture status, extending existing open source system management (and possibly virtualization/cloud management) frameworks to manage high-density ARM clusters, doing field trials of ARM-based data centre solutions, and bringing Fedora to the next generation of ARM technology.

Although the majority of my activity will shift from teaching to applied research, I will continue to teach the SBR600 Software Build and Release course in order to bring the research experience back into the classroom. I'll also continue to participate in the TeachingOpenSource.org initiative. As an Industrial Research Chair, I will also have a bit more of a public-facing role, representing CDOT and advocating the use of energy-efficient systems to local SMEs.

Many thanks to Red Hat for partnering with Seneca on this initiative, and I look forward to (continuing to!) work closely with Red Hat's incredible technical staff. I also thank the many companies and organization who wrote letters of support for the grant application, and look forward to collaboration and possible future partnerships with those organizations. And I particularly want to thank Seneca for its support of applied research, my colleagues at CDOT for their encouragement and for creating such an awesome environment to do applied research, and for the team that wrote the grant application under intense pressure and tight deadlines last November.

Watch this space for updates!

Element 14's Wonderful Forums Considered Harmful

nospam@example.com (Chris Tyler) — Fri, 09 Mar 2012 12:41:43 -0500

Element 14, the web presence of one of the Raspberry Pi distributors, Farnell, operates a wonderful forum system. However, there is one significant problem with their system: under their terms of use, a person who is under 13 is prohibited from using the forum (and those between 13 and 18 from using it without their parent's explicit consent).

This understandable requirement, probably a result of US legislation (and perhaps legislation in other jurisdictions?), is at odds with the Raspberry Pi's stated focus on children (hence the "considered harmful" jab).

I'd encourage the Raspberry Pi community to use forum and wiki systems that don't exclude the device's target audience from participating! Perhaps Element 14 would consider a revision to their Terms of Use, or a dedicated forum with special rules that would enable children to participate. In the meantime, the Raspberry Pi Foundation's forums and the E-linux Wiki do not have age restrictions on participants.

Open Source Translation Database

nospam@example.com (Chris Tyler) — Thu, 08 Mar 2012 12:36:22 -0500

Andrew Smith has released his Open Source Translation Database project, which contains thousands of open source translation files and can populate new translation files based on previous translations. In the released form this in incredibly useful -- and he has ambitious plans for new features and capabilities such as suggesting strings to be used in new projects based on the number of available translations.

Congratulations, Andrew, on this launch!

Seriously, CBC?

nospam@example.com (Chris Tyler) — Sat, 28 Jan 2012 12:51:44 -0500

Going to the CBC this morning, I found this:

I have three problems with this:

The CBC is our public broadcaster, funded in large part by tax money. It should support wide access.
I'm not running IE, I'm running Firefox. The ad is lying to me. If they're able to detect I'm not running the latest version of IE, they should also detect that I'm not running IE at all. My browser is not old, either -- I'm running the latest release of Firefox, which contains several features not yet supported by IE.
IE does not run on my platform (Linux). The ad is a waste of time for me and a waste of money for the advertiser. The pages to which the ad links are all specific to Windows, with no consideration for those running Mac OS/X, Linux, or any other platform.

The ad text seems to imply endorsement. Does the CBC actually endorse the position that the only acceptable end-user computing platform is Windows on an x86 computer? Is increasing the monopoly of a foreign corporation a suitable goal for a taxpayer-funded public broadcaster? I trust not.

Fedora ARM on the Raspberry Pi at Seneca CDOT

nospam@example.com (Chris Tyler) — Wed, 19 Oct 2011 16:53:37 -0400

What happens when you combine a $25/$35 computer, a major Linux distro's secondary arch effort, and a college that's deep into open source?

You get Fedora-ARM running on the Raspberry Pi at Seneca CDOT!

Here's a tiny video peek...

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There's a lot of optimization still to be done (including X11) but look forward to a Raspberry Pi Fedora image (spin/remix), Fedora 15 for ARM, and the Raspberry Pi device itself all being available next month.

(In or near Toronto? There are three talks related to Fedora ARM and/or the Raspberry Pi at FSOSS next week).

Let's see some Leadership on Broadband Access

nospam@example.com (Chris Tyler) — Sun, 03 Apr 2011 19:14:29 -0400

The inclusion of broadband-for-all-Canadians in the Liberal platform is an important step in the right direction. And while reliable rural broadband access is an obvious priority (as David Humphrey notes), the Liberal strategy does not go far enough: even current broadband access in our cities falls well short of what is needed to be globally competitive.

Canada's low average population density makes any broadband rollout a challenge. But there is an opportunity here: it's time for a leader to step up and set a realistic and challenging next-generation broadband goal, in the style of Kennedy's "We choose to go to the moon" speech. Setting a goal of 1 Gbps to every household in the country within three years would show real leadership. It would be a huge challenge, but we have the technology (wired and wireless), and it's where we need to go to stay in the game.

Gnome Documentation Hackfest

nospam@example.com (Chris Tyler) — Thu, 17 Mar 2011 09:13:46 -0400

For the next six days, CDOT is hosting some members of the of the GNOME documentation team for a documentation hackfest in preparation for the upcoming GNOME 3.0 release. On Friday we're holding an informal lunchtime talk to introduce the Seneca and Gnome communities -- and if you're in the greater Toronto area and are free, you're welcome to join us!

Fedora ARM PandaStack

nospam@example.com (Chris Tyler) — Wed, 09 Mar 2011 13:19:58 -0500

The PandaStack I mentioned previously - a stack of PandaBoards mounted on threaded rods, powered by a modular ATX power supply - is now a fully-functional part of the Fedora ARM project koji buildsystem.

For anyone interested in building a similar stack, here's the parts list and assembly instructions:

15 PandaBoards (or whatever quantity you wish to stack; the photo here shows 11 boards, since we have temporarily removed 4 for various device driver test projects)
15 barrel connectors
1 ATX 750W modular power supply (note: higher-rated power supplies may not have more current available on the +5v rail, which is what is used in this project)
4 threaded #4-40 stainless steel rods. (Note: BeagleBoards accept a #6-32 thread, but PandaBoards have smaller mounting holes).
1 pack (100) 0.25" nylon spacers
1 pack (50) 1.25" nylon spacers
2 packs (10) stainless steel acorn nuts
SD cards, ethernet cables, network switch
hacksaw, soldering iron, solder, wire strippers, heat-shrink tubing, heat-shrink gun (or embossing craft gun), multimeter

Cut the threaded rods to size with the hacksaw. Stack the boards on the rods, reversing the orientation of every second board so that it is upside down with the ethernet jack facing the opposite side of the stack; this will result in ethernet and power jacks down two opposite sides of the stack, with serial ports on another side and no connectors on the remaining side (which is the "bottom" of the stack). Use the 1.25" spacers between adjacent boards in a right-side-up/upside-down pair, and the 0.25" spacers between pairs. The grounding strips on the top of each ethernet/USB connector tower will just touch the plastic cases of the LED drive transistors on the adjacent board in each pair. Fasten the stack with the acorn nuts.

Gather the barrel connectors in groups of five. Connect each group to the +5 volt (pin 1) and ground (pin 2/3) leads of a molex connector from the ATX power supply (cutting off the cable connected to the molex connector, and ensuring that the barrel connectors are wired center-positive). Solder, then insulate with shrink-wrap tubing. Take the motherboard connector of the power supply, pull off all of the leads except pins 8 (PWR_OK) and 16 (PS_ON), solder those leads together, and insulate with shrink-wrap tubing. Plug the molex and motherboard connectors into the ATX supply.

Place the stack on its side on a wire shelf for convection cooling. Test the power supply leads to ensure you're getting a solid +5 volts, burn and insert your SD cards, connect your ethernet cables, and connect the boards one at a time to the power supply unit with the barrel connectors.

Enjoy your silent tower of computing power!

Running Fedora ARM without ARM Hardware, Made Easy

nospam@example.com (Chris Tyler) — Mon, 28 Feb 2011 16:41:16 -0500

The Fedora ARM secondary architecture project reached a significant milestone last week with Paul's announcement of the beta 1 release.

Interested in ARM but lacking ARM hardware? Not a problem! Fedora includes support for ARM virtual machines, and I'm packaged up a preconfigured ARM VM for your convenience:

ARM virtual machine package: http://scotland.proximity.on.ca/arm/armvm/noarch/armvm-f13beta1-15.fc13.noarch.rpm
Repo config for staying up-to-date on ARM VM releases: http://scotland.proximity.on.ca/arm/armvm/noarch/armvm-release-1-1.fc13.noarch.rpm

The armvm package will install a preconfigured ARM virtual machine named "f13-arm-beta1" with a 2GB image and a 128MB memory footprint. Since x86_64 processors don't provide hardware support for ARM processor virtualization, the ARM VM will run slowly compared to i386/x86_64 VMs, but the performance should be tolerable on most machines (Atom netbooks excepted). You can manage the VM with virsh or virt-manager. I've tested these packages on F13 and F14, but not on F15 Alpha yet. (By the way: the root password on the VM is "fedoraarm").

Enjoy!

(Please don't forget that both the Fedora ARM beta release and the armvm package are very definitely at the pre-release/beta stage of maturity. In particular, updating the armvm package will REPLACE your arm VM with a new image - beware!).

Temperamental Power Supply

nospam@example.com (Chris Tyler) — Wed, 23 Feb 2011 00:25:50 -0500

Today, the ATX power supply for the PandaStack I described in my last post is working happily. I have no idea what changed... which is a bit worrisome.

PandaStack

nospam@example.com (Chris Tyler) — Tue, 22 Feb 2011 09:43:47 -0500

Our "PandaStack" of PandaBoard builders (shown here with 9 of the 15 builders installed) is now ready to run as part of the Fedora ARM build farm. However, I've run into a weird problem -- the ATX power supply I bought to power the boards works fine with 1-3 boards, but Something Bad happens when a fourth board is connected. It's not a capacity issue as far as I can see; it seems to be related to noise. Time to borrow a scope and take a close look at waveforms ... in the meantime, we'll power some of the boards with the ATX supply and some with stand-alone power bricks.

PandaBoard Building Fedora-ARM

nospam@example.com (Chris Tyler) — Mon, 07 Feb 2011 23:48:17 -0500

We're adding a group of dual-core, 1GHz, 1GB PanadaBoards to the Fedora-ARM build farm. Paul Whalen and I hacked up the PandaBoard builder filesystem at FUDCon and I tested it with the farm on Thursday -- so far, it appears to build about twice as fast as the older GuruPlug builders. The PandaBoard's randomly-assigned-at-boot MAC addresses did force us to take a new approach to builder identity, though, because our previous approach of serving the identity via DHCP was no longer practical.

We ordered a total of 15 PandaBoards; 12 have arrived, and the others should be shipped shortly.Two are being set aside for testing, and we'll get the other ten building as soon as possible.

Our plan is to stack the boards on threaded rods, powered by an ATX power supply; the stack will be run on its side (with the boards oriented vertically) to aid in convection cooling. More photos to follow as we get this running! (Yes, that is a Powered by Fedora badge on there )

Coyotes on the Runway

nospam@example.com (Chris Tyler) — Sat, 29 Jan 2011 03:34:37 -0500

So I've safely arrived at FUDCon. Oddly, our plane was delayed for two reasons: the inbound flight was late due to a storm in Winnipeg (not so odd), and there was a "Coyote Strike" by a plane that landed just before we took off -- so they had to check that the runway area was animal-free before we were cleared for takeoff.

Coyotes in Arizona, yes. But Toronto?!

Looking forward to a great day of talks tomorrow! Hope I have two brain cells awake to rub together -- doubly so for the students, who are now on the prowl for food...

Changing the Open Web

nospam@example.com (Chris Tyler) — Fri, 28 Jan 2011 08:57:54 -0500

My colleagues in the Centre for Development of Open Technology have been doing some amazing work enhancing the open web. One of their libraries, Popcorn.js, enables web video to move beyond being a box on the page to become a part of the hyperlinked, dynamic web. With a ton of frantic hacking by the Popcorn team which began on Tuesday morning (!), PBS launched an interesting web page that night showing analyst's comments synchronized to a video of the US President's State of the Union speech. PBS comments about the effort are posted on The Rundown.

You should check out what these folks are doing with 3D on the web -- the Javascript port of the Processing data visualization language, Processing.js -- point cloud data -- and web audio!

Update: Dave Humphrey has blogged about the work that he and his team did on the SOTU page with PBS.