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hpr1630 :: Bare Metal Programming on the Raspberry Pi (Part 2)

This episode discusses interrupt handling, and program loading using the Xmodem protocol

Hosted by Gabriel Evenfire on 2014-10-31 and released under a CC-BY-SA license.
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The second episode in a series on bare metal programming on the Raspberry Pi. This episode builds on part 1 by showing how interrupts work on the RPIs ARM chip and the framework I created to manage them. It then goes on to describe how an interrupt-enabled serial driver works. From there, the episode shows how we can use the serial cable in conjunction with a loader program to enable us to load bare-metal programs onto the RPI without having to copy them to the SD card each time. In the process, the episode describes the XMODEM protocol that the loader users for the file transfer process.

Here is some of the source material that I used while working on this little learning experience.

Links


hpr1629 :: Banana Pi - First Impressions

Banana Pi first impressions

Hosted by Mike Ray on 2014-10-30 and released under a CC-BY-SA license.
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The Banana Pi - First Impressions

They say duplication is the sincerest form of flattery, substitute the word of your choice for 'duplication'.

The Banana Pi is made in China and bears an uncanny resemblance to the Raspberry Pi.

Not just the name, the board is fractionally larger, some of the features on the board are similarly placed:

  • 26-pin GPIO
  • 3.5mm analogue audio jack
  • RCA composite video jack
  • SD card slot

There are things the RPI does not have:

  • Power button
  • uBoot button
  • Microphone
  • USB-otg port (otg = on-the-go, a bi-directional USB port)
  • SATA connector

The processor is a dual-core running slightly faster than the Raspberry Pi, although to be fair, of course, the RPI can be over-clocked.

The Banana Pi has twice the RAM and a dual-core processor.

The SoC is the ARM Allwinner A20.

Getting my Hands on a Banana Pi

My first Banana dropped through the letterbox a couple of days ago.

Thanks to some kind soul on the Raspberry Pi Facebook group who described the connectors on the edges of the board I narrowly avoided plugging the power supply into the USB-otg port. The power micro-USB is on the underside of the board between the SATA power and data connectors which are on the upper side of the board.

Can't really say much about it because I can't actually see the build quality, but it feels nice. The PCB is fractionally thinner than the RPI.

Problems

I had an initial struggle to find a download link for any images.

The downloads page of lemaker.org has a two row table on it which appears to be upside-down and it has links to Google-drive, two different public DropBox links, a MS One-Drive link, and something I didn't initially find, an FTP link.

Both of the DB links are duff because they have suspended the account because of excessive traffic.

This is the FTP download link:

http://filez.zoobab.com/bananapi/mirror/

Available Images

When I found the FTP page I grabbed images for:

  • Arch Linux
  • Bananian-latest
  • Lubuntu
  • Raspbian

I downloaded and extracted all of these images to my Debian desktop machine and tried to write and boot them in succession.

The first I tried was Arch, on the assumption that would not have a desktop installed.

After writing the card I looked at it on my Debian machine with parted and it appeared to have two partitions. As with the Raspberry Pi there is a small FAT16 partition and a bigger ext4 partition.

The FAT partition contained the same files as the Raspberry Pi:

  • config.txt
  • cmdline.txt
  • kernel.img

And some others I can't remember.

In addition it contained:

  • uEnv.txt
  • uImage

It appears uEnv.txt is equivalent to the Raspberry Pi cmdline.txt file, and uImage is, of course, the kernel.

So oddly it has the files for the RPI and it's own in the FAT partition.

Then I tried Bananian, and this appears to be Debian Wheazy for ARM.

Similar story with the FAT partition.

It is a very minimal installation which has little more than the Linux Standard Base (LSB) packages. I like this because I like to have control.

Sound and Stuff

I found a review from April this year that said the sound driver snd-bcm2835 was not available. At the name snd-bcm2835 my heart sank because I expected the BPI to have the same stuttering text-to-speech problems as the RPI.

Not expecting much I did, as root:

apt-get install alsa-base alsa-utils

Looking through /lib/modules/... blah blah I found a driver called:

snd-aaci.ko

I did:

modprobe snd-aaci

And then:

speaker-test

And I got pink noise!

Next I did:

apt-get install espeakup
update-rc.d espeakup defaults
modprobe speakup_soft

And speakup burst into life with no stuttering!

Immediate Conclusions

The online community and code-base for the Banana Pi is not yet very mature, and because the origin of the beast is China, a lot of what's out there is in Chinese.

But it is growing. And after all, it took the RPI a while to take off and go ballistic.

At the moment I would say the Banana Pi is not for the faint-hearted or the total newbie, although, a lot of newbie questions are generic and don't have machine-specific answers.

Links

LeMaker page:

http://www.lemaker.org/

Australian community page with forums:

http://www.bananapi.com/

The worst thing about the Banana Pi is, when writing emails about it, and these show-notes, typing the word 'banana' and knowing when to stop!


hpr1628 :: OggCamp Interview with Peppertop Comics

A short interview with Mark of Peppertop Comics.

Hosted by corenominal on 2014-10-29 and released under a CC-BY-SA license.
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In today's show, Philip Newborough interviews Mark of Peppertop Comics. Peppertop Comics create free, open-source web comics. The comics are produced on Linux using Inkscape and MyPaint.

The Greys.

The interview was conducted at OggCamp 14, a free culture unconference, held in Oxford UK on the weekend of October 4th-5th 2014.


hpr1627 :: 5150 Shades of Beer: 0001 He'Brew Hops Selection from Smaltz Brewing Company

Beer, drinking same


Hosted by FiftyOneFifty on 2014-10-28 and released under a CC-BY-SA license.
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Smaltz Brewing Company - He'Brew (The Chosen Beer) Hops Collection

David's Slingshot - Pours golden, like an American lager, large head that subsides, rye aroma. Blend of multi-grain malts, an emphasis on hops w/o being excessively hoppy. Citrus taste from the hops. Malts: Specialist 2-row, Carmel Pils, Rye Ale, Crystal Rye, Vienna, Wheat, Flaked Oats Hops: Cascade, SAAZ, Summit, Citra, Crystal

Genesis Dry, so dry you could be excused for wanting a glass of water to go with your beer. Bready, not biscuity, like a fresh sourdough loaf, almost makes you want to spread butter over your beer. Just enough hops to be interesting rather than annoying. Just a little sweet on the back end, so subtle you'll likely miss it on the first sip. Watery mouth feel. 5.5% ACL. Malts: Specialty 2-row, Munich, Core Munich 40, Wheat, Dark Crystal Hops: Warrior, Centennial, Cascade, Simcoe

Bittersweet Lenny's R.I.P.A. Double Rye (an ode to comedian Lenny Bruce). Pours very dark amber, small head. Aroma of sweet rye bread. Sweet honey taste w/o being cloying, washed away by the hops. Strong rye flavor, much more than Slingshot. Malts: 2-row, Rye Ale Malt, Torrified Rye, Crystal Rye 75, Crystal Malt 80, Wheat, Kiln Amber, Core Munich 60 Hops: Warrior, Cascade, Simcoe, Saaz, Crystal, Chinook, Amarillo, Centennial

Hop Manna IPA Pours medium amber with a good head. Little distinct aroma. For the hops enthusiast who doesn't want other flavors getting in the way, but still not so hoppy that the hops get in the way of the hops. Hoppy enough to satisfy most hops heads without making your tongue feel like it is under assault from the Hop High Command. Malt: Specialty 2-row, Wheat, Munich, Vienna, Core Munich 60 HOPS: Warior, Cascade, Citra, Amarillo, Crystal, Centennial Dry Hop: Centennial, Cascade, Citra Even though hoppy beers aren't my preference, Smaltz/He'Brew were 4 out of 4 winners. If you see this brand, grab it with both hands. Even if I hated the beer, I'd be a fan because each bottle lists the malts and hops, giving the home brewer a shot at replicating the brew and the expert consumer a hint of what the beer is going to taste like before purchasing.


hpr1626 :: Opensource.com: Recalling OSCON 2014.

The Opensource.com team recalls its experience at OSCON 2014

Hosted by semioticrobotic on 2014-10-27 and released under a CC-BY-SA license.
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In this episode: Recalling OSCON 2014.

18 interviews with speakers of upcoming OSCON 2014

The O'Reilly Open Source Convention—or OSCON, as it's popularly known—is one of the world's premier open source events. For more than a decade, open-minded developers, innovators, and business people have gathered for this weeklong event, which explores cutting edge developments in the open source ecosystem. This year, Opensource.com visited OSCON, held July 20–July 24 at the Oregon Convention Center in Portland, OR (USA).

Read more: http://opensource.com/business/14/7/speaker-interview-series-oscon-2014

Open source talks: OSCON 2014 speaker interviews

Eagerly awaiting another year of open source wonders, the Opensource.com community caught up with a handful of notable OSCON speakers to gather behind-the-scenes stories about their passions for open source. Our eBook book collects the interviews we conducted.

Read more: http://opensource.com/resources/oscon-2014-interviews

Keynotes from OSCON 2014 Day 1

Our own Jason Hibbets and Jen Wike were live blogging from OSCON 2014! Day 1 talks include:

  • Shadaj Laddad: The wonders of programming
  • Making a difference through open source
  • Wendy Chisholm: Introvert? Extrovert? Klingon? We've got you covered.
  • Bringing OpenStack based cloud to the enterprise
  • Will Marshall: Building an API for the planet with a new approach to satellites

Read more: http://opensource.com/life/14/7/oscon-2014

Keynotes from OSCON 2014 Day 2

We're back with keynote coverage on Day 2 of OSCON 2014! Day 2 talks include:

  • Tim Bray: Threats
  • Racing Change: Accelerating Innovation Through Radical Transparency
  • Simon Wardly: Anticipating the futurean introduction to value chain mapping
  • Checking Your Privilege: A How-To for Hard Things Leslie Hawthorn (Elasticsearch)
  • Tim O'Reilly: What kind of world do we want to build?

Read more: http://opensource.com/business/14/7/keynotes-day-2-oscon-2014

Keynotes from OSCON 2014 Day 3

We're back with keynote coverage on Day 3 of OSCON 2014! Day 3 talks include:

  • Andrew Sorensen: The concert programmer
  • Frank Willison Award for contributions to the Python community
  • Beth Flanagan: Yes, your refrigerator is trying to kill you: Bad actors and the Internet of Things
  • Ryan Vinyard: Open manufacturing: Bringing open hardware beyond 3D printing
  • Rachel Nabors: Storytelling on the shoulders of giants

Read more: http://opensource.com/business/14/7/keynotes-oscon-2014-day-3

hpr1625 :: 40 - LibreOffice Calc - Other Functions

A quick look at some miscellaneous functions in Calc.


Hosted by Ahuka on 2014-10-24 and released under a CC-BY-SA license.
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We spent a lot of time looking at some Financial and Statistical functions. I don't propose to go into the remaining types of function in nearly the same depth. That would draw out the series without benefit to most people. But I do want to highlight some of the functions in the other categories so that you have an idea of what is possible in Calc. Remember that if you need to know more about them Google is your friend. - For more go to http://www.ahuka.com/?page_id=875


hpr1624 :: Penguicon 2015 Call for Talks

I am looking for people who can present tech/FOSS talks at Penguicon 2015


Hosted by Ahuka on 2014-10-23 and released under a CC-BY-SA license.
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I am the coordinator for the Tech Track at Penguicon 2015, which is a combined FOSS/Science Fiction convention held every spring in the Metro-Detroit area. The 2015 event will happen April 24-26 at the Westin Hotel in Southfield, MI. The theme for the upcoming year's event is Biotechnology and medicine, looking at how technology is affecting our health and life. But we want a lot of different talks as well, so I will be happy to accept proposals that look at things like cloud computing, security, hardware hacks, and anything else that would be of interest to geeks and hackers.

Links:


hpr1623 :: Tech and Coffee at OggCamp

Another set of OggCamp interviews. I talk to Keith Milner and George Doscher from Tech and Coffee.


Hosted by beni on 2014-10-22 and released under a CC-BY-SA license.
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In this episode of interviews from OggCamp 2014 I talk to George Doscher who co-founded (or founded, I really don't know) the Tech and Coffee Google Plus hangout. You'll find him at

https://plus.google.com/+GeorgeDoscher

and on Tech and Coffee under

http://techandcoffee.info/

In the second interview I talk to Keith Milner who has some interesting and fairly technical stuff to tell you about mobile networks. He also talks about unencrypted traffic on the carrier networks and why it's even more important for you to use encryption when using the web on your mobile. You find him under

https://plus.google.com/+KeithMilner


hpr1622 :: An interview with Michael Tiemann

An Open Source News Break from Opensource.com: An interview with Michael Tiemann

Hosted by semioticrobotic on 2014-10-21 and released under a CC-BY-SA license.
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Links


hpr1621 :: OggCamp Interview with James Tait

A short interview with James Tait of Canonical.

Hosted by corenominal on 2014-10-20 and released under a CC-BY-SA license.
Listen in ogg, spx, or mp3 format. Series: Interviews | Comments (0)

In today's show, Philip Newborough interviews James Tait of Canonical, the company behind Ubuntu.

James talks about his work on the now defunct Ubuntu One project, and his current work with Ubuntu Phone. James is a super-nice guy, knowledgeable and very gracious. He was a pleasure to interview.

James Tait (right) with Mark Shuttleworth (left) at Corinthia Hotel Budapest.

PICTURED: James Tait (right) with Mark Shuttleworth (left).

The interview was conducted at OggCamp 14, a free culture unconference, held in Oxford UK on the weekend of October 4th-5th 2014.