• Home
  • Help
  • Search
  • Login
  • Register
  Show Posts
Pages: [1]
1  Hardware and U-Boot firmware / Hardware / Re: Help building a serial cable for Guruplug on: May 25, 2010, 12:57:06 PM
I have an Asus WL500gx wireless router that has an 8 pin header with two 3.3V serial ports (TX0, RX0, TX1, RX1, GND, +3.3V, RST and NC). I'm planing to connect port 1 to the GuruPlug. GP serial port has GND, TX, RX and +3.3V.

Can I directly connect GND-GND, RX1-TX, TX1-RX? Is any other component needed to isolate the devices?

A common ground is all that's needed for regular RS232, so I don't see any reason why it wouldn't work in this case wiht 3.3V signalling.    The signals are relative to ground so if you tie the grounds together the signals should be compatible.

I'm not an EE person, so do everything at your own risk of course.
2  General Category / General Discussion / Re: GuruPlug - Received Yours Yet? on: May 18, 2010, 07:29:57 AM
I e-mailed Globalscale about my order yesterday and they replied saying they won't be shipping my order until at least June.  So that will be a solid 2 months from order to delivery.  That's quite a bit longer than my first sheevaplug order placed when the sheevaplug was announced.
3  General Category / General Discussion / Re: Guruplug Server Plus built-in serial port? on: May 03, 2010, 08:54:38 AM
If you are adding the JTag device to allow an application to use the RS232 port (not for debugging purposes), you could use a USB-2-Serial converter in the standard USB port instead.  It might be cheaper/easier. Smiley
For me I need the serial port for the serial console so I can tftp boot and things so I can write a new distro to the flash.  The JTAG device is simplest for now.  I bet, however, that for a few dollars I could rig up a board to convert the serial lines on the guruplug to a regular (albeit 4-conductor) serial port.
4  General Category / General Discussion / Re: Guruplug Server Plus built-in serial port? on: April 29, 2010, 12:01:07 PM
Kind of.  Yes, it has an asynchronous serial port available.  No, it isn't at standard RS232 voltages.

RS232 uses +- 3-15v signaling, while this uses 0-3v signaling.

You will need something to convert the voltages if you want to use it with RS232 compatible devices.
Okay.  While I could probably come up with a chip to convert it, for now I'm just going to order the jtag device.  It's too bad they don't have it built in like they did on the sheevaplug.
5  General Category / General Discussion / Guruplug Server Plus built-in serial port? on: April 28, 2010, 02:19:59 PM
I know the guruplug server plus does not have a built-in USB to serial adapter.  But it appears that there is a connector labeled uart RS232.  Is that a real serial port?  Can I connect with a normal null-modem cable to that and get a serial console?  Looks like a normal 4-wire serial interface to me, from the pictures.
6  Linux Stuff / Kernel / Re: original sheeva kernel needs some work on: June 12, 2009, 06:57:13 PM
I run numerous servers (web, mail, etc) on the big, bad internet without any firewall at all.  There is no problem.  A firewall simply cannot protect you from insecure applications anyway.   In other words, on my mail server only port 25, 465, 143, 110, 993, and 995 are even open and I want them open.  Hence iptables does nothing.  Even if iptables was running it would do nothing to protect the server from being attacked through these services.

Really iptables is most effective at controlling traffic flowing across the device (IE a routing firewall).  Sometimes iptables is useful for controlling access to certain services by certain subnets.  But really that's a kludge (albeit useful one) to compensate for the fact that some services are extremely braindead and don't allow you to control which interfaces it is listening for, or doesn't have any concept of ACLs.  I was finally forced to run iptables on my VPS when I needed to use NFS once.  And then later my VPS became my openvpn concentrator and I needed iptables to control access between my various private subnets (one subnet per household in my family... privacy needed to be controlled).

All that said, however, I needed iptables on my plug computer as well, for reasons that have to do with dans guardian filtering.  So I ended up installing the 2.6.30rc8 kernel.  It worked great.  Before I installed it, though, I netbooted it over tftp to make sure it would work for me.  when it did, I simply overwrote the original kernel in uboot.  I do agree with you, however, that having a more functional kernel ship stock would be ideal.  Most folks won't need iptables, but some might, so it may as well come with the ko modules anyway.
7  Hardware and U-Boot firmware / Hardware / Re: My SheevaPlug is very unstable on: April 26, 2009, 08:23:13 AM
Well after it ran great for a week, yesterday I noticed it had crashed again (blue light was out too).  This is definitely not what i expect from a linux device.  I did have an SD card in the slot at the time (although it wasn't mounted or in use). 

I'm wondering if I did just get a bad unit.  It's really hard to tell.  So many variables.

Looks like the blue light is a heartbeat light.  I believe you can control the light if you build a 2.6.30 kernel.
8  Linux Stuff / Linux distributions / Ubuntu NFS root on: April 20, 2009, 09:23:37 PM
Is there a tarball of the standard ubuntu install that I can use in an NFS root?  All I can find is the jffs2 image and a tarball of a stripped-down, busy-box -based root.
9  General Category / General Discussion / Booting the sheevaplug firmware in Qemu on: April 19, 2009, 10:59:09 AM
For a variety of reasons, it would be helpful if I could get the same firmware that's being used by the SheevaPlug (currently U-Boot and Ubuntu 9.0x) to boot up in qemu on my linux machine.  Qemu emulates all the hardware that the plug has, with maybe the exception of the ethernet interface, but a custom kernel would fix that.

Here's what I've done so far:

qemu-system-arm -mtdblock ubuntu-9.0.5.Release.jffs2 -pflash u-boot-rd88f6281Sheevaplug_400db_nand.bin -cpu arm926 -net user -net nic -m 512 -kernel uImage.sheeva.040309

All of these files are in the various downloads from either Marvell or GlobalScale.  I'm not sure if I'm using the right u-boot image, nor am I sure if specifying it as pflash is the correct way to do it.  Basically I get a black screen with nothing on it.

Has anyone done this yet?  For those still waiting to get their device, qemu may let them play with things and try building software.  For me it lets me play around with things before I commit them to my plug.
10  Hardware and U-Boot firmware / Hardware / Re: My SheevaPlug is very unstable on: April 15, 2009, 03:11:30 PM
I wonder if the SheevaPlug isn't sensitive to certain things like USB keys, etc.  Maybe it's some electrical thing inherent in the design.  Basically it occurred to me that my office is about 500 feet from the switch.   We've never had any problems with computers operating pretty darn near 100 MBit/s on these long run ports, but maybe the SheevaPlug's ethernet circuitry just isn't quite up to making that kind of long connection.  I've run it unplugged from ethernet all day and it seems to be up still.  Maybe I'll take it home now and plug it into my home network on a short cable and see how stability is over the weekend.
11  Hardware and U-Boot firmware / Hardware / Re: My SheevaPlug is very unstable on: April 15, 2009, 08:56:28 AM
After I hit the reset button this morning, the plug lasted only 19 minutes before it stopped responding and the blue LED went off.  No messages on the serial console.  Nothing.   I was logged in over ssh and running top and that just froze as well. 

Checking the log file this time, I see:
JFFS2 notice: (654) check_node_data: wrong data C
RC in data node at 0x129b7000: read 0xa1d3c8f7, calculated 0xee32cdcf.

That message seems to have come up a few times in the logs, including about a dozen times before I even bought unit (back in January), probably during the factory's testing phase.  Not sure if this message is related to my crash, though.
12  Hardware and U-Boot firmware / Hardware / Re: My SheevaPlug is very unstable on: April 15, 2009, 08:41:51 AM
I checked the logs this morning when I got into work.  There is nothing in the log except "mark" items all the way up until 17:40 last night, which is when it stopped responding.  The blue light was also off when I got in, I noticed.  Very odd.  I'm keeping a serial console open, so I'll see what happens.  Hopefully it's software.  If not, well RMA time.  Certainly for the application I plan to use this, I can't have it crashing every day.
13  Hardware and U-Boot firmware / Hardware / My SheevaPlug is very unstable on: April 14, 2009, 09:05:28 PM
In the 2 days I've been playing with it, I've had it stop responding three times, both to IP and to the serial console.  I know of some that found their plug crashed when attaching a usb device.  So far I've not done that.  I am still running the stock software, with the exception that I've added a couple of packages like vim tinyproxy, and ntp.  I didn't run the plug much before installing these packages so it is possible ntp or tinyproxy is bringing it down.  I wasn't attached to the serial console when the last crash happened today, so I don't know if I got any kernel panic messages.  I'll have to keep a better watch.

Anyone else experienced this type of thing?
Pages: [1]