Review by Gary, aka chunkyks Thanks to some work I'd been doing, I found myself targeting the SheevaPlug http://www.plugcomputer.org/ for a project, despite not actually having one of these plugs myself. mp3car.com very generously offered to send me one, as part of a process to provide innovation grants to forum users. I cannot thank them enough for the opportunity. See this product on the mp3Car Store here. I'm a long-term unix and Linux software developer, so anticipate this review leaning in that direction. features Low Energy ARM chip [entire device is rated at 5W] Small Form-factor [entire computer inside a regular sized power brick] Comes with Ubuntu 9.04, but trivially reflashable Communications with the outside world: Gigabit Ethernet, USB2.0, SDIO. Also has a USB slave port as a serial console 512M DDR2, 512M Flash pros Excellent documentation Does exactly what you'd expect. No less, and probably a little more Extremely affordable Stock Ubuntu install. Zero configuration. Out of the box it boots and can be logged into cons There's an expectation that you are familiar with Linux. Slow boot times and disk access Lack of useful kernel modules in the box Occasionally the plug feels warm to the touch The Short Review: I love this device, and everyone should get one. It's a fully functional Linux box, and magically Just Works for all my needs. See our forums for the Full review, details, and thoughts for the future and follow up with conversation Full Review: Right out of the box, it does exactly what I expect a modern computer to do. You can log into it, install software from the Ubuntu repositories, and run stuff on it. The software corpus available for easy download is massive, and includes all the usual development tools and user programs you'd expect or need. The plug is running an ARM chip - as is common for low-power embedded devices. The ARM architecture is a little bit different from your typical desktop computer. To me, this is a Good Thing, as I subscribe to the belief that portable code running on more architectures is better than code that doesn't. [Notably, while porting to other architectures, bugs often surface that otherwise wouldn't have]. On the downside it means that occasionally, you may find software that doesn't work for you on the plug. During testing I found nothing I needed that didn't work immediately, but the potential is there. It's absolutely worth starting with the new plugger howto [http://www.plugcomputer.org/plugwiki...Plugger_How_To ] and making a couple system changes to ensure you won't run into problems. There are apparently some situations where an inopportune update immediately after getting the plug can render it un-bootable. It's easily re-flashable, but it's a lot easier to just edit a couple files first. The plug wiki and documentation tends to assume that the user has a certain level of familiarity with Linux or unix. Most notably, the wiki in a few places [not the least of which is the new plugger howto] just said ‚Edit this file, without further elucidating. Anyone familiar with unix will recognize this; editing text on unix is historically a matter of both holy wars and extreme difficulty to the novice user. This reviewer has edited the wiki to provide a little more help, but as a whole a small amount of Linux knowledge is certainly helpful. Something I haven't commented on up until now is that there's no easy way to plug a screen into the Sheeva. This is self-evident from looking at the device, but bears mentioning. I successfully used remote X over ssh with the plug, but primarily the Sheeva is a command-line device that you ssh into - again, a level of unix familiarity cannot hurt. Up to now, everything I've commented was things that are ‚good‚ in my view, but some of them may be perceived as problems. There are a couple of real downsides to the plug: Boot times are noticeable [on the other of 20-30 seconds, which feels high for a small embedded device] and large un-cached disk accesses tend to be pretty slow. This is because the plug uses a file system called jffs2, which is very good for wear-leveling and error handling in flash, but can be slow. There are good alternatives [eg, ubifs], but switching to them again requires re flashing the plug, something I will almost certainly be doing in the near future. If you plan on doing a lot of disk writes, or large disk writes [as I do], then it's definitely better to pick up an SDIO card or a USB flash drive, and write to that. Those are supported out of the box. The plug feels warm to the touch. I believe it's still not using much power, but there's obviously some inefficiency somewhere. Some mp3car forum users have converted their plugs to run off 12V as provided by their car, and apparently the new 12V PSU dissipates less energy in the form of heat. 3.3 Running my own software The specific goal for me on the plug is to run my pet project, OBD GPS Logger. Due to past experience with portable code, I was happy to see obdgpslogger build first time on the plug, after installing the requisite tools [six packages plus their dependencies, starting with what was in the box]. I didn't build the GUI tools [no need for them here] but obdsim, obdgpslogger, and the conversion tools worked immediately. On the CD in the box, or for free download, are cross-compiling tools; obdgpslogger also builds just fine using that environment. One problem was that as it comes in the box, the Sheeva doesn't have the necessary kernel modules [aka ‚Äúdrivers‚Äù] that an mp3car reader might need; specifically, ftdi for an OBDPro scantool [http://www.obdpros.com/ ] or similar, or any bluetooth modules. Since the OBD devices I have are all either ftdi or bluetooth, this was an issue. This has been discussed on the Sheeva forums [http://plugcomputer.org/plugforum/index.php?topic=84.0 ], where the best [only] proposed answer was to reflash the kernel on the device. While that's not difficult in practice, that's kinda fearsome to someone unfamiliar with Linux or serial consoles. I came up with a somewhat different solution to the ftdi problem: I wrote a small userland tool using libftdi [which is available in the Ubuntu repositories] to proxy my ftdi device to a unix pseudoterminal. At time of writing, it's not fully working with obdgpslogger yet, but it works enough to access my OBDPro scantool. Overall, I found the Sheeva a fantastic tool; it really is a complete Linux system that does everything I need. 4 Future Uses In writing this review, I found myself coming up with various ideas for using the plug, beyond a simple host for obdgpslogger. Of particular interest is that it's simply a low-cost device that you can run always-on and always-connected-to-the-internet for cheap. For want of a number, a quick back-of-the-envelope calculation says that it costs me about 1.7 cents per day to run, or about six dollars a year... and I live in a part of the US where electricity is relatively expensive. Some food for thought for others picking up one of these plugs: Webcam. The plug can run a webcam and either host a live stream, or regularly upload photos to another site. Great for those of us with jobs and dogs. This way my power-hungry desktop can remain asleep during the day and I can still watch my dogs. Storage server. Plug a huge external hard drive into it and use it for network attached storage. Typical uses might include a streaming server for a PS3 [using the fantastic mediatomb http://mediatomb.cc/ a backup server, or a bittorrent tracker or downloader. Combine a few of these things and you get: Leave an RSS reader running on the plug all day, reading streams from torrent sites and automatically downloading things you like. When you get home in the evening, turn on your TV and PS3 and start watching. Imagine if your cable company's on-demand didn't suck - that's what this is. In the past, I've used squid to block ads and as a network cache; the Sheeva is perfectly placed to handle that. Nowadays, fast internet and intelligent browsers make a lot of that moot, but squid can still pull off some pretty neat tricks. Home automation. It's nice to have something you can ssh into before leaving work, perhaps to start a coffee machine or something. The Sheeva could perhaps control some X10 devices. For people interested in a whole new worldview of instant messaging, the Sheeva makes a great Bitlbee server. Similar to DD-WRT, it's not hard to imagine complete images to flash to the device. The RSS-bittorrent-PS3 configuration above could easily be prepared to an image, and have end-users simply download and flash the whole bundle. On the topic of DD-WRT, some people don't like to reflash their wireless routers or similar devices; the Sheeva could run all the services you otherwise would have liked your wireless router to do [such as DHCP with static allocation - the main reason I upgraded to DD-WRT in the first place] See this product on the mp3Car Store here.
Updated 12-26-2009 at 08:45 AM by Jensen2000
