2009-10-02

SheevaPlug - first impressions

At last, my SheevaPlug Development Kit has arrived!

For those who don't know yet what the SheevaPlug is, you can have a look at this short CNET article or Marvell's slightly longer blurb about this wonderful little device.
I ordered mine (UK version) from Globalscale about 2-3 weeks ago, to basically replace my long trusted WRT54G running openWRT with something that has a little more punch and I/O capabilities. The truth of the matter is, I almost never use the WRT for WiFi, but having an always on & completely customizable Linux low power "server" has proved invaluable (Samba share for easy data interchange between any machine, DHCP server, bootp/tftp server, nmap & other networking tools provider, etc.), and I had been waiting for some time to see something like Marvell's plug computer come out, as it's basically a glorified hacked WRT54G, without the unneeded Wifi/network hub features.

For those who can't be bothered to read the whole post (and who can blame them!), I'll jump right into the main points of my first impressions:

The not so good:
  • Globascale's delays in shipment, and total lack of response when asked for updates. Granted delays are likely unavoidable (I doubt they're shipping Sheevaplugs by the truckload right now), but that doesn't explain why it took about 2 weeks of repeated e-mails to sales to get a simple status update on the order.
  • No choice but to use Fedex for shipping if you're not in the US. Granted, once it's shipped, the delivery is fast indeed, but considering the shipping delay, you might as well want to use regular post and spare a few bucks.
    Also, since Fedex are really happy to help with the obnoxious EU VAT & Customs Duty extortion scheme, you will be hit by 46% retroactive VAT on import (€31.20 - I really wish I was making this up), meaning that, as usual, no matter what you do, amount in $ = amount in €, and you still have to pay €99 for a bloody $99 item. Better believe this is the last time I import anything with Fedex.
    HEED MY ADVICE - DO NOT IMPORT ANYTHING WITH FEDEX, EVER!!!

  • Unlike the most excellent US removable plug (see below), the UK plug is just a common adapter to fit over the US socket, so it's not as sleekly designed. Not that big a deal, but it adds to the overall height of the device when used in plug mode. It would have been nice to see an integrated UK plug in the way the US one is. Also, the Globalscale UK devkit photos don't make that as clear as they could.
  • The mainboard is now rev. 1.3 and very different from the reference mainboard you see in the documentation (see below). For starters, there is no longer a separate mainboard for JTAG and SDIO, and the solder-able port for an ARM JTAG connector is gone. Gone as well is the generic GPIO connector. There still seems to be a small JTAG port, but with only 8 connectors and a non-standard smaller socket too be fitted in, it will be a pain to interface with. Not sure if many people would put single board vs 2 separate boards design as a disadvantage, but I was kind of planning on using the standalone expansion board as a cheap JTAG device (it has the very well known FT2232 JTAG IC on it) but now using the SheevaPlug hardware as a JTAG interface to other boards, or as a general purpose IO device, is going to be less of a possibility for your regular electronics hobbyist.
    UPDATE: for some of the new ports pinouts (still no JTAG desc), have a look here
  • Even idle, the device seems to run a bit hotter than I anticipated (It's certainly running hotter than my WRT54G). Definitely not that hot (akin to one of the numerous power bricks you have in your house), and most likely the heat is due to the PSU rather than the chip themselves, but still, I've seen power bricks run cooler than that (the 12V DC WRT brick being one of those). Of course, anybody who hears "heat" automatically thinks "increased power consumption", so I don't know how that translates into wasted wattage. My guess is this might be due to using a 110V/220V compatible PSU. Using a localized source voltage PSU for 220V -> 5V delivery would probably reduce the heat.
    [UPDATE 2009.10.08] The Plug does run scaringly hot when running at full load for a prolonged period of time, as I just found out through a rogue process.
    The metal parts on both USB and network sockets are almost burning when running for a long time at 100% of the CPU, and you wouldn't want to leave something in contact with them then. Still probably not hot enough to light up paper or plastic that would be in contact, yet quite scary... And it looks like the PSU unit does play some part in raising the whole temperature of the plug on full load. I also found that I had to enlarge some of the vents on my plug with a knife because they had been pourly moulded and were not entirely open. Still, I don't think Even then, there are too few vents on the current Plug and I don't think it is designed for adequate cooling! Something that definitely needs some improvement for later models.
    My advice: make sure you leave ample space around the plug, and check that all your vents are fully open.
The good:
  • Brilliant design from Globalscale. As somebody else said, whoever designed that removable socket for corded/plugged needs to have both a raise and a corner office. And despite the point I made above, the single mainboard layout is very well done (and rumour has it there is even an eSata port in there). Those guys have sharp engineers! The whole device itself feels both sturdy, inconspicuous, yet elegant. Even the cardboard packaging the plug is shipped in is very good design, so much so that I almost felt like taking pictures of the packaging. But then I thought, only Apple fanboys ever do something like that...
  • Does exactly what it says on the tin. The layout design might have changed, but you still get 2 USB ports (1 for debug), 1 SDIO port, 1 Gb Ethernet port and a computer with 512 MB RAM, 512 MB Flash, a most excellent 1.2 GHz ARM CPU, plus a JTAG device that's compatible with OpenOCD. Who could ask for more?
  • Can power a 2.5" USB HDD (tested with both a 5400 rpm 100 GB and a 7200 rpm 320 GB HDD). Impressive!
  • Loads of free space on the flash with the default Ubuntu installation
Alright, now it's time for opening the device and posting some pictures! Wait, are you telling me that the first thing you do when receiving a cool new toy is NOT tearing it apart to see what's inside? What on earth are you doing with your life?

Some pictures
  • That very well done removable socket/cord plug concealer
From SheevaPlug
  • Opening the plug (just remove the rubber pads to find the screws)
From SheevaPlug
  • Mainboard - top
From SheevaPlug
  • Mainboard - underside, with heatsink
From SheevaPlug
  • Mainboard - underside, without heatsink
From SheevaPlug
  • The device in action
From SheevaPlug

1 comment:

  1. Since you have SheevaPlug revision 1.3 you could upgrade it with an ESATA port. Here is how:
    http://mark.ossdl.de/2010/04/howto-upgrade-the-sheevaplug-with-esata/

    I ordered two Plugs months ago (and after that eight for friends) and was only to pay Fedex a 10€ toll-fee, but no tax at all. Maybe you just had bad luck or more motivated clerks than us here in Germany.

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