Self Driving Cars

I’m a believer in self driving car technology, and predict it will have enormous effects, for example:

  1. Our cars currently spend most of the time doing nothing. They could be out making money for us as taxis while we are at work.
  2. How much infrastructure and frustration (home garage, driveways, car parks, finding a park) do we devote to cars that are standing still? We could park them a few km away in a “car hive” and arrange to have them turn up only when we need them.
  3. I can make interstate trips laying down sleeping or working.
  4. Electric cars can recharge themselves.
  5. It throws personal car ownership into question. I can just summon a car on my smart phone then send the thing away when I’m finished. No need for parking, central maintenance. If they are electric, and driverless, then very low running costs.
  6. It will decimate the major cause of accidental deaths, saving untold misery. Imagine if your car knew the GPS coordinates of every car within 1000m, even if outside of visual range, like around a corner. No more t-boning, or even car doors opening in the path of my bike.
  7. Speeding and traffic fines go away, which will present a revenue problem for governments like mine that depend on the statistical likelihood of people accidentally speeding.
  8. My red wine consumption can set impressive new records as the car can drive me home and pour me into bed.

I think the time will come when computers do a lot better than we can at driving. The record of these cars in the US is impressive. The record for humans in car accidents dismal (a leading case of death).

We already have driverless planes (autopilot, anti-collision radar, autoland), that do a pretty good job with up to 500 lives at a time.

I can see a time (say 20 years) when there will be penalties (like a large insurance excess) if a human is at the wheel during an accident. Meat bags like me really shouldn’t be in control of 1000kg of steel hurtling along at 60 km/hr. Incidentally that’s 144.5 kJ of kinetic energy. A 9mm bullet exits a pistol with 0.519 kJ of energy. No wonder cars hurt people.

However many people are concerned about “blue screens of death”. I recently had an email exchange on a mailing list, here are some key points for and against:

  1. The cars might be hacked. My response is that computers and micro-controllers have been in cars for 30 years. Hacking of safety critical systems (ABS or EFI or cruise control) is unheard of. However unlike a 1980’s EFI system, self driving cars will have operating systems and connectivity, so this does need to be addressed. The technology will (initially at least) be closed source, increasing the security risk. Here is a recent example of a modern car being hacked.
  2. Planes are not really “driverless”, they have controls and pilots present. My response is that long distance commercial aircraft are under autonomous control for the majority of their flying hours, even if manual controls are present. Given the large number of people on board an aircraft it is of course prudent to have manual control/pilot back up, even if rarely used.
  3. The drivers of planes are sometimes a weak link. As we saw last year and on Sep 11 2001, there are issues when a malicious pilot gains control. Human error is also behind a large number of airplane incidents, and most car accidents. It was noted that software has been behind some airplane accidents too – a fair point.
  4. Compared to aircraft the scale is much different for cars (billions rather than 1000s). The passenger payload is also very different (1.5 people in a car on average?), and the safety record of cars much much worse – it’s crying out for improvement via automation. So I think automation of cars will eventually be a public safety issue (like vaccinations) and controls will disappear.
  5. Insurance companies may refuse a claim if the car is driverless. My response is that insurance companies will look at the actuarial data as that’s how they make money. So far all of the accidents involving Google driverless cars have been caused by meat bags, not silicon.

I have put my money where my mouth is and invested in a modest amount of Google shares based on my belief in this technology. This is also an ethical buy for me. I’d rather have some involvement in an exciting future that saves lives and makes the a world a better place than invest in banks and mining companies which don’t.

Degrowth Economy

Just read this article: Life in a de-growth economy and why you might actually enjoy it.

I like the idea of a steady state economy. Simple maths shows how stupid endless growth is. And yet our politicians cling to it. We will get a steady state, energy neutral economy one day. It’s just a question of if we are forced, or if it’s managed.

Some thoughts on the article above:

  • I don’t agree that steady state implies localisation. Trade and specialisation and wonderful inventions. It’s more efficient if I write your speech coding software than you working it out. It’s for more efficient for a farmer to grow food than me messing about in my back yard. What is missing is a fossil fuel free means of transport to sustain trade and transportation of goods from where they are efficiently produced to where they are consumed.
  • Likewise local food production like they do in Cuba. Better to grow lots of food on a Cuban farm, they just lack an efficient way to transport it.
  • I have some problems with “organic” food production in the backyard, or my neighbours backyard. To me it’s paying more for chemically identical food to what I buy in the supermarket. Modern, scientific, food production has it’s issues, but these can be solved by science. On a small scale, sure, gardening is fun, and it would be great to meet people in communal gardens. However it’s no way to feed a hungry world.
  • Likewise this articles vision of us repairing/recycling clothing. New is still fine, as long as it’s resource-neutral, e.g. cotton manufactured into jeans using solar powered factories, and transported to my shopping mall in an electric vehicle. Or synthetic fibres from bio-fuels or GM bacteria.
  • Software costs zero to upgrade but can improve our standard of living. So there can be “growth” in some sense at no expense in resources. You can use my speech codec and conserve resources (energy for transmission and radio spectrum). I can send you that software over the Internet, so we don’t need an aircraft to ship you a black box or even a CD.

I live by some anti-growth, anti-consumer principles. I drive an electric car that is a based on a 25 year old recycled petrol car chassis. I don’t have a fossil fuel intensive commute. I use my bike more than my car.

I work part time from home mainly on volunteer work. My work is developing software that I can give away to help people. This software (for telecommunications) will in turn remove the need for expensive radio hardware, save power, and yet improve telecommunications.

I live inexpensively compared to my peers who are paying large mortgages due to the arbitrarily high price of land here, and other costs I have managed to avoid or simply say no to. No great luck or financial acumen at work here, although my parents taught me the useful habit of spending less than I earn. I’m not a very good consumer!

I don’t aspire to a larger home in a nice area or more gadgets. That would just mean more house work and maintenance and expense and less time on helping people with my work. In fact I aspire to a smaller home, and less gadgets (I keep throwing stuff out). I am renting at the moment as the real estate prices here are spiralling upwards and I don’t want to play that game. Renting will allow me to down-shift even further when my children are a little older. I have no debt, and no real desire to make more money, a living wage is fine. Although I do have investments and savings which I like tracking on spreadsheets.

I am typing this on a laptop made in 2008. I bought a second, identical one a few years later for $300 and swap parts between them so I always have a back up.

I do however burn a lot of fossil fuel in air travel. My home uses 11 kWhr/day of electricity, which, considering this includes my electric car and hence all my “fuel” costs, is not bad.


In the past I have written about why I think economic growth is evil. There is a lot of great information on this topic such as this physics based argument on why we will cook (literally!) in a few hundred years if we keep increasing energy use. The Albert Bartlett lectures on exponential growth are also awesome.

Hybrid Optical-Microwave Communications

A few weeks ago I visited the ITR at the University of South Australia, where I studied some time ago. My former PhD superviser, Bill Cowley is part of a team working on a interesting new hybrid optical/microwave communications scheme.

Their reasoning is that spectrum is becoming more and more congested. Free Space Optical (FSO) communications offers a great way to increase bandwidth. Free space means sending light signals through the air rather than through a fibre, for example over a distance of 10km. Like Wifi, but at higher (optical) frequencies, and with potentially enormous bandwidth for data.

The have a really neat trick – combining the FSO link with a regular microwave link, with Forward Error Correction (FEC) applied across the combined channels. This makes a system that is more robust than either link alone. The two channels have complimentary properties. For example if cloud affect the FSO link, the microwave link will be less affected.

I think this is a really novel idea. Normally FEC bits are sent through the same channel, e.g. on a CD extra bits on the disk are used to protect the music recording on the same disk from errors (like a scratch). On your cell phone both the speech data and the error protection bits pass through the same radio channel. With this scheme it’s like a DVD is combined with a CD to protect against bit errors.

Here is a picture of the optical part of the link, in a small room on the top of the ITR building:

The ‘receiver’ on the left hand side is a home-brew design based on 150mm Fresnel lens; the telescope of the right is a 125mm Meade which can either be used in visible wavelengths (via the web cam directly behind the scope) or at 1550 nm (detector and IR camera attached to the T splitter). The link extends over a 12km path to a site in the Adelaide Hills.

More information on the ITR’s FSO page. Thanks Bill for showing me the system and providing information for this post.

Baboons, Mesh networks, and Community

At both Village Telco Workshops I had the pleasure of meeting David Carman and Antoine van Gelder, who founded and now administer the Scarborough Wireless User Group (SWUG). Scarborough is located almost on the southern tip of Africa, on the edge of Cape Town, South Africa.

SWUG uses a mesh network to provide Internet access to people in Scarborough, as DSL is largely unavailable. DSL is connected at one edge of the mesh, and is then distributed throughout Scarborough and some neighboring villages. Users buy their own routers and local youth have been trained to flash and install the routers as mesh nodes.

The mesh network also provides connectivity to those who couldn’t otherwise afford it, and to kids whose parents don’t wish to pay for Internet. The result is wider access which promotes greater community participation in local applications.

Subscription payments are voluntary, with paying traffic prioritized over non-paying. This has worked surprisingly well to ensure that everyone gets access and we are able to afford sufficient bandwidth. The accounting system is fully automated (using bank deposit email notifications), so administration is hands-free and anonymous. The accounting system removes what would otherwise be a serious admin burden. It uses pmacct and changes iptables rules on the fly.

David has installed several communication forums (including phpbb, mediawiki, argwatch). Mailman is most effective. Email is the preferred modality for the naive user and mailman works well for the naive moderator. However the kids on the mesh appear to be using Facebook to organise themselves!

SWUG has lead David and Antoine into some interesting projects.

They have written a very cool application called ArgusWatch to track incursions of Baboons into the community! The Baboons have a habit of sneaking into peoples homes and making a big mess. One thing that fascinates me is how “local” this application is. We are used to most web apps having a global audience. Makes me think there must be many very useful, very local applications that could be written to address local community issues.

David has become skilled at real world mesh network issues like Wifi propagation and is a strong contributor to the Village Telco project. Antoine has been very busy building Afrimesh, a GUI for the Village Telco that is now running on the Mesh Potato. Funny how these community projects change the direction of our lives. I started out messing around with Asterisk on a DSP chip in 2005 and some how I now build Mesh Potatoes!

Talking to David got me thinking about mesh networks and community.

Now a community used to be something local, for example I might get together with other parents from my daughters school and work together to get a school crossing installed. Local people with a common interest working together. A social organization with social aims, compared to say a business organisation that has business goals.

Then the Internet came along and widely dispersed people with common interests could be connected. So now we have widely separated people with a common interest working together. A good example ais the Open Hardware projects I have been working on as part of the Free Telephony Project. Individuals from Canada, China, Bulgaria, Australia working together to develop complex telephony hardware designs. Together we built leading edge IP-PBX technology – as good or better than products coming from giant hardware companies. One example is the BlackfinOne – a community built open hardware Linux board, forerunner to the IP04:

Mesh networks close the circle. A mesh network depends on neighbors working together. My Internet comes via my neighbor’s router. There is a dependency that encourages people to work together and help each other (even if only by leaving their router on). So just like the first example we have local people working together, but this time facilitated by Internet technology. SWUG is a social enterprise that outperforms the incumbent Telco in delivery of broadband to the people of Scarborough.

In my travels to East Timor I found an interesting counter-example. East Timor has very little local Internet infrastructure and very little local content. Most of the Internet traffic goes straight up a satellite dish to ISPs in other countries. I found no examples of IP traffic going from a browser to a web server in East Timor – it all left the country as a first step. As you can image the cost of accessing information on the Internet is prohibitive ($5-10/hour where people would be lucky to earn that in a week). I wonder what that does to a community?


Thanks David Carman for checking this post and providing additional details of SWUG.

Kjell Aleklett Lecture

Yesterday I took a much needed break from Mesh Potato hacking and pedaled into Adelaide University to see a lecture by Kjell Aleklett, who is the president of the Association for the Study of Peak Oil and Gas who is visiting Australia this week.

Couple of important points that I took away:

  1. Kjell explained the physical process by which oil percolates through porous stone to oil wells – he then made the point that economists think that oil flows are propelled by money, not physical processes. In other words economists (and therefore governments) think money can overcome physical supply problems. Oops.
  2. The estimates of greenhouse gas emissions and hence global warming are based on continued growth of fossil fuel use. However these estimates do not take into account the actual peaking of oil, gas, and coal supplies. When the limited supply situation of fossil fuels are modeled, greenhouse emissions are constant over the next 50 years. If fossil fuel supply is limited, you limit huge increases in carbon dioxide concentrations.
  3. All current economic models assume unlimited future growth. Growth requires fossil fuels, which are reaching the limits of physical supply. For example if our population increases, we need a new suburb, and new cars to handle commuting. So if fossil fuels are limited, this means that from now on economic growth will be curtailed. No economic growth means the current economic systems break.


My original post on Peak Oil.

Some thoughts on our obsession with economic growth.

East Timor – OLPC Pilot

One of the main reasons for the February East Timor trip was to assist the Seaton OLPC group investigate a possible OLPC pilot later this year. Here are some thoughts based on my experiences with the OLPC in East Timor:

  1. Everyone we met who saw and played the XO’s (teachers, students of all ages) “got it” – they worked out how to drive the laptops quickly and could see great benefit to Timor. Their eyes lit up with the possibilities!
  2. Education is generally of a poor standard, is non-compulsory and it not widely encouraged by parents. If students don’t want to go, they don’t go and no one really cares. However education would greatly benefit Timor and help resolve some of the nasty social and violence problems lurking under the surface (75% unemployment, afternoon drunkenness of teenagers, teenage pregnancy and resulting high birth rate).
  3. School is boring in Timor. It is taught in Portuguese (to students whose native language is Tetun) with inadequate books (not enough and poor quality) via rote learning. XOs would make it fun.
  4. I have no doubt teachers and students alike would quickly come up to speed with XOs. Where we need to work is on integrating the XO into teaching – for example lesson plans for the next 6 months that can be agreed upon with the teachers.
  5. Cultural: There is a family pecking order in society of Father-Mother-then children in descending age order. For example Dad eats first and young children get whats left over. This means if an XO is taken home, a child’s bigger brother will be within his rights to grab it for himself. This may be a good thing (spreading laptop usage around the family) as long as it makes it back to school. Will the XO be valued and cared for in the home? Possibly – it may be viewed as a status symbol like satellite TV or a mobile phone. Status is big there – a person with no income will have a mobile phone. They will sleep on a dirt floor, have no proper kitchen or toilet but have satellite TV – a big dish standing next to a Gilligan’s Island type hut made of palm leaves.
  6. I have no doubt that introducing these laptops to classrooms will be very beneficial to students and teachers alike. The XO will literally change the course of the lives it touches. We should work together to make a pilot deployment happen ASAP.


East Timor – We really do have road rules now!
East Timor – Cultural and IT

Prototype Village Telco Raided

Dabba are a South African company that have been operating a prototype Village Telco network in the Orange Farm township near Johannesburg. It’s fair to say that Dabba inspired much of the Village Telco project. They use unlicensed 2.4 GHz spectrum to run VOIP over Wifi links. The result is disadvantaged people get a telephone at a reasonable cost.

A few days ago the South African communications regulator (ICASA) confiscated Dabba’s Wifi equipment with zero notice. Just stompted in and took it, apparently based on a complaint by the incumbent South African Telco (Telkom) regarding interference. There has been no explanation by ICASA of the actual technical problem, and no evidence of any interference. The Wifi equipment was type approved (this means samples have been rigorously tested to prove they do not interfere with other services).

Dabba was proving Internet and Phone service to a skills development centre, an aids orphanage, and an Internet cafe. On line communities are outraged. Given the amount of evidence provided it sounds like Telkom made an unsubstantiated claim and the regulator jumped in prematurely using a very heavy hand.

The good news is that Rael from Dabba is determined to rebuild the network ASAP – well done Rael and I hope we get some clarity (or an apology) from ICASA soon.


ICASA – Stealing from AIDS Orphans

IT Web article

Village Telco Google Group Thread on Dabba Wifi Confiscation

Peak Oil and Why Growth is Evil

Oil has no future. Really. Just look at this graph of oil discovery (borrowed from this excellent Peak Oil Overview). The graph shows oil discovery (in billions of barrels) per decade.

Now oil discoveries peaked at about 500 billion in the 1960’s, about the time I was born and started crawling towards anything electrical and driving my Mum crazy. World wide we use around 85 million barrels/day, or 30 billion a year. So when you read the next mainstream media article about a “billion barrel oil discovery” remember that 1 billion barrels is just 12 days world oil consumption.

So 30 billion barrels a year is 300 billion a decade. Now look at the graph above. In how many decades did we discover more than 300 billion barrels?

And what is this fixation with economic growth? Politicians seem to be telling us we are all doomed unless we constantly grow the economy. The worst thing about the financial crisis is that we might now get “growth”. growth Growth GROWTH!

The problem with x% growth is that it is exponential. That means we consume more and more every year. It goes to infinity real fast. More oil, more water, more people, more money, more debt. Just 5% growth means doubling every 14 years. One small oversight guys: nature is finite. A good example is yeast growing in a Petri dish. Nature always shuts down exponential growth. Always. Usually by killing everything in the Petri dish.

Economics is busted as it depends on the ultimate unsustainable practice – exponential growth.


An earlier post on Peak Oil.

Open Hardware 3 Years On

In 2005 I started working with Asterisk on the Blackfin. This led to the Free Telephony Project, and the idea of using open hardware techniques for telephony. The idea of open hardware (people collaborating to build free hardware designs just like open software) was a big experiment, especially when it came to commercial products.

Back in 2006 I posted my initial ideas on Open Hardware. Much has happened since then. Many people and companies are now working on Blackfin Asterisk projects. New projects, and even businesses have spun out of the project. Coolest of all – open hardware products are now in volume production, as real world, commercial products like the IP04. People are buying and using these products – often in preference to products developed using traditional closed development models. Open hardware works!

Open Hardware in Business

As the idea of Open Hardware matures a few patterns seem to be shaking out. The form of open hardware distributions seems to be the schematic. Companies are largely keeping the PCB designs and other tooling information closed. This gives them some sort of protection against direct copies hurting their business. At least that is the perception – I actually think the PCB is a small part of the total business picture.

Directly cloning open hardware designs doesn’t seem to work as a business model. The prototype IP04 design (schematic and PCB) is entirely open – all the CAD files are free for anyone to use. In theory this means you can give these files to your local surface mount assembly line, ask them to build 100 IP04s for you, and be in the IP04 business. I get 1-2 emails/month from companies intending to do this.

However in practice you need the skills to find small hardware faults, an understanding of the design, experience in building and flashing the firmware, testing, QA, support. Like many valuable things in life, these skills must be acquired, and can’t be copied. You need that hacker mindset to understand how the beast works. The IP04 hardware and software is rather complicated so you really need the support of the community. This requires a community outlook. Those interested only in $ don’t share these values, lose patience and move on.

The real power of open hardware seems to be providing a baseline for your product development. Take the hardware and tweak it. Add a different line interface, more ports, less ports, hardware rather than software echo. Add your software application to the baseline build system. Code up your own build system.

Open Hardware, Closed Tools

Most people are developing their open hardware with closed source schematic/PCB CAD tools. Bit of a pity, but ultimately hackers will use the best tools for the job, open or closed. That is why many hackers use open source software – it’s just better. Hopefully this gap in CAD tool performance will be filled soon.

Open Hardware is Software

Curiously, the “open hardware” projects are dominated by software complexity. The effort involved in the fun stuff (soldering, schematic and PCB design) is dwarfed by the effort involved in the software, e.g. maintaining build systems, porting applications, testing. The majority of my time on this project has been spent on build system work, then software, then the actual hardware. This is part of the general trend of hardware functionality shifting to software. The vast complexity of the software means a lot of time needs to be spent managing it with configuration control and build systems.

Open Hardware is Hard to Grok

Just like Open Software in 1992, the concept of Open Hardware is hard to understand. The ground rules are still being worked out. Full points to companies like Atcom for overcoming these concerns and embracing open hardware.

Some memes that are particularly tough:

  1. If it’s open won’t people just copy my product? Well, this doesn’t seem to be a big problem in practice. Many other factors are required for a successful business, as discussed throughout this post. Value tends to shift to other parts of the business, and the advantages of sharing and community outweigh closed development and secret sauce.
  2. For the open source community, re-flashing commodity hardware (e.g. OpenWRT on a WRT54) is now common practice. However moving from this to open hardware takes a big shift in mindset. Here is the dirty little secret of the hardware game: hardware products are 95% software. The man hours invested something like OpenWRT or Asterisk are orders of magnitude greater than those put into developing the WRT54 hardware or a PCI telephony card. And yet open software communities wait nervously for the next commodity hardware box, only to find it doesn’t have the feature they require, or goes out of production, or the manufacturer won’t release the internal data, or it doesn’t have enough flash etc. In the mean time the manufacturers and chip set vendors are having a great time making money from using your open software in their products.
  3. Open hardware is not that hard. The truth is that a modest community effort can develop and bring into production a full custom open hardware device (designed exactly to your specification), and arrange to have it volume manufactured at a reasonable price. We have done exactly this with the IP04.

Extreme Open Hardware

Some of the radical uses of Open Hardware I had hoped for haven’t happened yet. I am particularly interested in seeing Open Hardware being used to help people in developing countries. For example new business models like IP04 assembly in Africa for local markets, or volume manufacture at cost price (give 20,000 people telephones for $500,000). The Mesh Potato is part of a fresh new project where we are using open hardware and software to help bring telephony the developing world.

IPO Opportunity

I do this work largely as a volunteer (although I derive a modest income from IP04 sales and contract work), so like many hackers I choose to work in areas that interest me. This year I have been shifting my focus to telephony for the developing world. I am not personally motivated by the business side. So the IP04, while very usable, still requires an understanding of the Linux command line and Asterisk conf file skills (although the GUIs are steadily improving).

There are several companies working with open hardware Blackfin Asterisk technology. So far I see companies that are good at manufacturing, some that are good at build systems, and fewer still that are good at software optimisation, hardware and DSP. A big opportunity exists for a company that can combine strong technical skills with solid marketing and business skills to produce a bug free, feature complete turn-key appliance product. This has proven surprisingly difficult to do – even with all of the hardware and software available in open form. To me this drives the lesson home that a business is much more than just the technology.

You know as a community we bring all of the above technical and business skills together. So the project as a whole is thriving, just no one person or company has a monopoly on the intellectual property and profits. And that, I put to you, is a good thing.

Open Hardware for Hackers

Call me a geek, but the greatest reward for me is a bunch of people soldering tigether their own uClinux Blackfin Asterisk boards at home, and bringing up their very own uClinux IP-PBX. There is nothing quite like seeing the root prompt come up on a Linux board you soldered together yourself, or hearing that phone handset ring for the first time. Open hardware gives the hacker the remarkable power to build IP-PBX products that took large teams to develop just a few years ago.


  1. An introduction to Open Hardware, written as the Free Telephony Project was just starting.
  2. See the amazing range of hardware and software in the Free Telephony Family Tree.
  3. Steve Song’s thoughts on Open Hardware for the Developing world.

The Mesh Potato Part 1

In June 2008 I attended the Village Telco workshop in Cape Town, South Africa. Cape Town in June was rainy and cold, however the South African people were really friendly. While in South Africa I also attended the Wireless Africa workshop, however that’s another story for another post!

The Village Telco (and I quote) is an easy-to-use, scalable, standards-based, wireless, local, do-it-yourself, telephone company toolkit. We were in Cape Town to work out how to build this puppy.

Steve Song of the Shuttleworth Foundation pulled together a fascinating team of people from the development, VOIP, mesh networking, and business communities. The team was small (about 10 people) and very “hands on” in their outlook and skill sets. The breakfast and dinner conversations were fascinating, for example funny stories about broken down hotels in some developing countries, and sad stories about the poverty of others.

You can click here to put a face to all the names (thanks Steve).

I had never experienced a workshop quite like this before. Not sure if it was the team of people, the small size, or Steve’s leadership, but we really “fired”. I am generally allergic to meetings – in my previous day job I was infamous for avoiding, hating, and general bad behavior where meetings are concerned. However I managed to stay awake and even attentive through most of the 5 days the Village Telco workshop.

One of the outcomes was the decision to build a little box called the Mesh Potato.

The Mesh Potato in a nutshell

The Mesh Potato is a 802.11bg mesh router with a single FXS port. It is designed to provide telephony via VOIP while simultaneously facilitating a mesh cloud. It is an open hardware and open software design. It will run off a nominal 12VDC, from either a mains supply or solar PV system, and be priced in the range of currently available Wifi routers (sub US$100).

Key features:

  1. Runs B.A.T.M.A.N. mesh routing software, Asterisk, the Speex voice codec, and Oslec echo cancellation.
  2. The target application is mesh routed VOIP networks, in particular (but not limited to) developing communities. An analog phone connects to the potato via the FXS port. When you make a call you potato talks to the potato down the street which talks to the next potato, and eventually to the destination. The mesh network can be augmented via backbone links and connected to the rest of the world via VOIP gateways.
  3. No cell phone towers, no land lines, no big Telcos required. A local entrepreneur can roll out his own Village Telco system using a modest server and a bunch of Mesh Potatoes. Community owned telephony.
  4. The mesh network is self organising and healing, if a node goes down B.A.T.M.A.N automatically re-routes the calls.
  5. We are building custom hardware specifically for developing communities using open hardware and software principles. I would like to push the meme that we can develop custom open hardware devices – no need to accept whatever is available off the shelf. You see most of the work in any appliance is software, so the idea of relying on closed, proprietary, not quite right hardware is obsolete.
  6. The Mesh Potato is open. Really Open. Key goals are to minimise binary blobs, proprietary software and make the hardware open. This means the potato will probably be Atheros based, as we can use the madwifi open source WLAN driver. It also means Speex instead of g.729, and Oslec instead of a proprietary echo canceller. The hardware schematics (at least) will be available. The potato will be a mass produced in very high numbers, therefore the open community now has a chance to set standards, rather than have to play along with “standards” based on closed hardware and software.

For the curious, Steve describes the origins of the Mesh Potato name in this post.

The Shuttleworth Foundation has generously decided to fund the initial phases of the Mesh Potato Development. The Shuttleworth Foundation is involved in many worthwhile projects, such as the Freedom Toaster and kicking off Ubuntu. Potato development will be my main activity for the rest of 2008!

Project Plan

We have divided the project into 5 milestones, M0-M4. We start at 0 because we are geeks, just be thankful we didn’t used binary. We have largely completed the planning stage and have kicked off development. We hope to have prototype potato hardware in early 2009.

Currently, we are working on M1 – Proof of Concept. The idea is to use Commercial Off The Shelf (COTS) hardware like a Ubiquity Nanostation 2 to develop a prototype that demonstrates all of the software components working together. We will develop many of the custom software components early in the project, using a mature hardware platform. Major software components will therefore be relatively mature when integrated into the prototype hardware, saving time and lowering overall risk.

Over the past few weeks I have been experimenting with OpenWRT on the Nanostation 2 – running test programs for Speex and Oslec and characterising the CPU load.

Atcom are very keen to work on the prototype hardware, and be the volume manufacturer for the Mesh Potato. Atcom have been pioneers in supporting Open Hardware products such as the IP04.

Hardware Architecture

Here is a mud-map of the hardware design:

One challenge is how to connect the FXS chipset to the Atheros SoC (glue logic in the figure above). The FXS chipsets require a TDM serial plus SPI bus. The TDM bus is typically a 2.048MHz serial bus that supplies one 8-bit speech sample every 125us (8kHz). The SPI bus is used for control and configuration of the FXS chip set (for example sensing off hook, switching the ringer on).

This glue logic was straight forward for the IP04 as the Blackfin CPU has a rich set of interfaces with good DMA support. The Atheros SoC is not quite as feature rich. It does have a SPI bus for talking to the SPI flash. This only has one chip select line however I figure some of the GPIOs could be used to gate access to other SPI devices.

So we need to build a TDM interface somehow. To reduce interrupt overhead and I-cache thrashing it would be nice if we can buffer 1-20ms of samples (8 to 160 8-bit samples) before we interrupt the Atheros SoC. This interface could be some logic or perhaps even a small micro-controller like a PIC. One other possibility is interfacing the TDM bus to the RS232 UART. The Atheros SoC does have a 16550 compatible UART with some sort of hardware FIFO, however we would need some tests to determine if the CPU overhead of using the UART is acceptable.

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The Mesh Potato promises to be something very special – an open hardware/software, community designed WiFi mesh router with Asterisk and a FXS port. Boy, I’m out of breath after saying that. No wonder we just call it the Mesh Potato. The Village Telco concept that it supports could bring telephony to millions. Please feel free to join our community – by subscribing to the Village Telco Google Group.