Embedded


Cellular and Computers and Conventions and Embedded and Networking07 Sep 2012 09:39 pm

Every year I’ve looked at Anime Weekend Atlanta as more than a chance to hang out with friends from out of town because of the rather unique situation having several laptop wielders in the same hotel room can present. Therefore, I come up with all sorts of hair-brained network schemes to get everyone online from the same connection, be it the wired connection in the hotel room or using a Yagi antenna to grab free WiFi from the lobby thru skylights or the floor. Last year’s was probably the most amusing: a Clear WiMax USB card plugged into a Cradlepoint router, connected to a normal wireless router with a Yagi antenna pointed downstairs to con ops where another router with a high-gain vertical antenna received the signal which was then repeated by a fourth router with an even higher-gain vertical. It was as insane as you can imagine!

This year, however, I’ve decided to just be “normal” and scale everything back to a reasonable level: I’ll use my T-Mobile 3.75G card with the aforementioned Cradlepoint for the precious little time I plan to spend in the hotel room.

It’s fortunate, as it saves a lot of room because I won’t be dragging a 16x16x10 or 20x20x12 box with stuff in it with me.

Guess I’m getting old. ;)

Cellular and Embedded and Networking and UNIX30 Jun 2010 03:25 pm

A random search of “T-Mobile Rocket Linux” on Google retrieved a post showing how to make the T-Mobile webConnnect Rocket Stick HSPA+ device work in Linux. This is relevant because as of June 17, the Atlanta metro area has HSPA+.

In my adventures with embedded computing, I’ve come across the PC Engines ALIX boards. These are slightly less expensive than Soekris’ and similarly capable. Their alix2d13 board has 3 LAN ports and 2 USB ports. pfSense 2.0 is currently in beta, and as it is based on FreeBSD 8-RELENG (future 8.1), it should have support for my UMG-181.

The article on making the Rocket Stick work in Linux showed its device ID: its device ID also exists in /src/sys/dev/usb/serial/u3g.c in FreeBSD 8-STABLE. As development on FreeBSD 8.1 continues, it may indeed be functional when 8.1-RELEASE is out.

Needless to say, I put a plan together. An alix2d13 equipped with a wireless card, loaded with pfSense 2.0 or similar, and paired with a USB aircard is the same concept of Cradlepoint’s WWAN routers. It also has the flexibility and extensibility of pfSense and the bonus of being open-source.

From the looks of things, the whole setup will run just under $200. I should be able to squeak this into my budget later on this year, maybe.

My tests of T-Mobile’s upgraded network with my UMG-181 have produced results as high as 4Mbps. My home DSL connection is 6Mbps for comparison. I do believe that I will have sufficiently fast access at this year’s hamfests and at conventions for sure. Now to implement this new project.

Embedded and Networking and UNIX07 May 2010 04:16 pm

Sometimes I dislike slow days at work as I start reading and reading and reading. I reread the EVDO Stompbox Project and something clicked with me: I remembered the mini-PCI slot in my net4501. While I’ve only used mini-PCI cards in notebook computers over the years, I never had a need to use it in the Soekris because I had a PCI wireless card and it has a single PCI slot.

But further research lead to something I’d read a while ago as well: the state of ral(4) in OpenBSD. Ralink released the hardware specs for their wireless chipsets without an NDA, so the drivers are very very very well written and stable, plus they support WPA-PSK.

I can find a supported Ralink-based mini-PCI wireless card for a very low price, u.fl-smaF pigtails are probably cheap, and I have several antennas for 2.4GHz already.

This solves one issue in the network box problem!

Cellular and Conventions and Embedded and Hamfests and Networking24 Apr 2010 12:16 pm

Earlier this week, I read on TmoNews.com that T-Mobile was making another promo on their webConnect (aircard) service. I had cashed in on a promo plan towards the end of last year for $50/mo instead of $60/mo, but this one is even more awesome: “Overage Free” rate plan for $40/mo. What this means is that while the (now) soft cap of 5GB exists, past that they may throttle you down to EDGE speeds. I can live with that, and the fact that it isn’t a guaranteed throttle makes it even better.

What does this mean for the net-in-a-box project? It means EPIC AWESOME. I no longer have to worry too much about whether or not it goes over 5GB, and even if we go over 5GB at a con, I’m certain that EDGE speeds are still faster than a hotel connection shared with a full hotel. That’s assuming they enforce it heavily.

Needless to say, I phoned up 611 yesterday morning and got the plan switched over. I definitely await the forthcoming summer activities with this semi-unlimited data plan!

Embedded and Networking and UNIX12 Mar 2010 11:45 pm

I decided to dig out the big plug strip and hook all the materials up to see if they worked together before I begin the pure DC phase of the experiment. After massaging pf a little bit to make the bridge work, I managed to get an IP wirelessly with the WAP plugged into the 3rd NIC port instead of the hub. All the devices cooperated nicely and it all seems to work fine!

Now to begin plotting on the second phase: acquiring the elements for powering the system via DC direct instead of multiple wall warts.

Once the power is figured out, then comes building the box itself. Going to need to do some measurements and figure placements out. Once the box is built out, field testing will commence!

Embedded and Networking and UNIX12 Mar 2010 10:15 pm

I loaded OpenBSD on the Soekris and did the necessary configuration tweaks to get all the interfaces assigned properly and the like tonight. I also adjusted the Cradlepoint (turning off WiFi, adding DMZ, etc.) for the system. Now to get it all hooked up and tested at some point.

Embedded and Netbooks and Networking and UNIX12 Mar 2010 04:49 pm

A few years back, some friends and I had the crazy idea to utilize my MFJ-1800 2.4GHz Yagi antenna and a PC set up as a “reverse AP” to allow us all to use the hotel’s free wifi at a convention. The only downside to this was that we didn’t have wireless for ourselves, but that wasn’t too big of a deal: we had circumvented the pay access in the room using technology. Sadly, that hole was plugged the next year, and we were forced to pay for access… Such is life.

Moving forward to last year’s convention and our staying in a different hotel, I decided that I’d just suck it up and pay for access as it wasn’t too much. Though, before we actually settled down in the room that evening, I had ran by the T-Mobile store at the nearby mall and came extremely close to purchasing one of the webConnect USB sticks (which I now have) so we would have access without having to pay the hotel. I opted against that, but planned to get one before the year was out. Fortunately for me, T-Mobile had a promo for $10 less/month on the access not long afterwards, so I now have one to use for access mostly everywhere.

The obvious item for aircard owners with friends that attend conventions and trade shows is to pick up one of the aircard routers on the market. While I own a Soekris net4501 and have long thought to emulate the EVDO Stompbox Project using it, the lack of good driver support in OpenBSD for the Huawei UMG181 webConnect stick and my dislike of iptables had me pick up a Cradlepoint CTR350 broadband travel router to use. One thing I missed in the documentation was the client limit of 15 on its wireless. While I seriously doubt I’ll ever exceed that number, having a hard limit on the amount of clients that could be attached didn’t sit well with me at all, so I started brainstorming.

Back last month, I set up an old Power Mac G4 as an OpenBSD router using the macppc port. It functions flawlessly, and the flexibility of pf continues to shine. I thought about one of the major purposes that Soekris boards are used for and ran by Micro Center to pick up a good 2GB CF card to toss in it once I get OpenBSD built out on it. Fortunately for me, the author of flashdist has disk images set aside already for the net45xx series, which I will throw on the CF card sometime this weekend. The only downside to this setup is the utilization of “double NAT” in connectivity. Of course, this is no different than what we’ve already been using, so I really don’t see an issue with it.

Just how am I going to get around the 15-client limit of the Cradlepoint? While I certainly could use the Soekris as an access point: it’s one of those little green boxes’ primary uses, I’d much rather have a dedicated WAP set up like I do at home because of a couple of small things that may not work right: namely, UMA for my Blackberry. Just so happens I have an old La Fonera wireless router with DD-WRT loaded on it. I ran this as my WAP for a while at the house, and I reloaded it with DD-WRT before the convention last year and set it up as the WAP. While it works flawlessly, it gets rather warm. Not too much of an issue for a system that will run very infrequently.

Now how does this all piece together? Turns out that every single device I plan to connect together to create this connectivity backbone runs off either 5v or 12v DC. The two 5v devices, the Fonera and the CTR350, can be plugged into a 12v source using cigarette lighter sockets. The Soekris and my old Netgear EN108TP 8-port hub are 12v, so they will plug right in. My original plan involved debricking the WGR614L I toasted last year and using it as it was 12v and would reduce the amount of cig plugs.

The trick to this was building a small power distribution panel with screw terminals so they’d be very secure. Turns out this would be more of a pain than I originally thought, so I went back to the original plan that I thought of: using Anderson PowerPoles for the power connections and a power panel with those on them. In the end, deciding to go with PowerPoles for the power connections really was best: I won’t be tied down to the power supply, so I could feasibly run the setup off my car’s battery if I so decided. I probably will never do that, but it is an idea.

Converting standard wall current to 12v for the network devices was something I mulled over a lot with my original plan. I needed a small (10A or so) power supply with a cigarette receptacle on it. The smallest I could find at work was 25A and way overkill for what I needed. After I decided on PowerPoles, the decision was simple: Astron SS-10 switching power supply. It’s quite small and supplies enough power: 7A continuous, 10A 33% duty cycle. I seriously doubt all this hardware I have will ever exceed 7A for more than just a short period of time.

Now the really hard part is figuring out how to connect all of this together in a secure matter. I’ve done a lot of research in the past couple of days on the “go boxes” used by people who handle various events. One idea that probably won’t be too difficult to set up is to build a shelf and mount it in a case of some sort for carry. I’d probably pick something waterproof like an ammo box in case I get rained on for the convention like what happened last year. Otherwise, I’ll build out something very easy to set up and carry.

Overall, this is going to be one fun project. I’m very glad I have just over 6 months to get it set up! I do think that in the long run, streamlining my portable network setup will be very beneficial for myself, my friends, my family, and whoever else I can think of.

If anything, it’ll give me something interesting to write about as I continue to build it out.

Conventions and Embedded and Networking and UNIX13 Oct 2006 06:05 pm

It’s fairly common knowledge that most hotels these days have free WiFi in at least part of the hotel. The hotel in question is the Renaissance Waverly that Anime Weekend Atlanta has been at the past three years. Their free WiFi is in the lobby/convention center area (basically the first two floors of the hotel) only. The hotel rooms on floors 3-14 can’t access it directly (believe me, we tried. both on the 4th floor last year and the 11th this year), so either you pay the $10/night to use the wired access, gimp it using a cell phone (be it GPRS, EDGE, 1xRTT, 1xEV-DO, or God forbid CSD or CDMA data) or do without.

We’d already decided to not do the $10/night and were just going to use my cell or something for access. Then I had a brainstorm the weekend before the con. I realized I could do basically a “reverse AP” by setting a wireless network interface as the “WAN” interface and then run the regular ethernet jack into a switch or hub. Not to mention that I’d recently picked up a 15dBi 2.4GHz Yagi antenna and have a Netgear MA311 PCI 802.11b network card, which is based on the Prism2 chipset.

Add all those together and what do you get? A semi-portable “OK let’s get these workstations on the wireless here STAT” setup. I say semi-portable because the board we pulled from a decomissioned firewall went in a rather heavy small form factor case. Definitely not light enough to toss in a laptop bag or a “Go Pack.”

I loaded m0n0wall on the machine for the sake of time. Had I had more time, I’d probably have done a “proper” setup on OpenBSD or whatever, but for our purpose, m0n0wall worked flawlessly. I’d be running it here if it let me assign the same static DHCP mapping to multiple MAC addresses (as I do like to sometimes pick my laptop off my desk and go to another room to access the net). Other than that one little quirk, which is a bit of a nonissue for most people, I like it.

At any rate, the final result looked like this. We had a clear line of sight to the skylights in what was Artists’ Alley that weekend (really the main convention area) and it worked wonderfully.

Because it worked so well, I’m going to be picking up a Soekris net4501 just for that purpose. It will end up living in my laptop bag and will serve as quick and dirty AP or quick and dirty “reverse AP” for a multitude of purposes. Not to mention giving my laptop bag a bit more “sturdiness” since I’m no longer carrying a notebook and textbooks in it in addition to my laptop.

If it works out well enough, I’ll probably pick up another net4501 or a higher model to replace my rapidly aging router machine. Or I’ll migrate it to a CF based setup. Right now I dunno for sure, but it should be fun either way. IPCop is small enough to fit on a 1GB CF card, so I may just do that. Though the Soekris is a lot smaller and wallmountable and would free up some desk space. But for now I’ll stick with IPCop on this old Deskpro 2000.

Embedded16 Apr 2005 01:13 am

Would someone like to explain to me how PalmOne’s new Tungsten E2 got by me? Really, I’m satisfied with the Treo, but wow that thing looks cool. Now if it only had a thumb-board instead of Graffiti 2. Then I might sell my Treo and get one.

But, for now. I sleep. (z_z).。o○zzz…