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31  Hardware and U-Boot firmware / Hardware / Is Your Plug dead? on: May 19, 2010, 12:11:24 PM

If your plug appears to have died;

Do NOT break the anti tamper seal, yet.

Email or phone  your supplier, detailing the problem, be polite!   

You should get an RMA number or similar and return the device.  Try to get a prepaid return parcel label from the supplier, the postage cost of returning a defective item is normally paid by the consumer, but its worth trying to get the supplier to pay!

If the plug failed within a few days, of delivery,  insist on a complete replacement device.  Do not accept  just a replacement power supply you have to fit yourself. The reason is,
unless you are a qualified electrical engineer, it is risky to be sent a replacement power supply and to fit it yourself. It is not a consumer replaceable part. It raises questions regarding  your own safety and also third party liability if the power supply you installed at a later date catches fire and burns down your house and your neighbour's house!

If your device has a EU approval mark, then if you are in the EU, you should have a TWO year mandatory warranty for electronic devices against failure due to manufacturer defects!  Although it is EU law, it has not been properly described and promoted, and not many people are aware of it.

Always approach your supplier for redress in the first case.

I have no idea about consumer law outside the EU,  You will have to find out the applicable consumer law in your own country.

Also, I have no idea of the law where the customer resides in one country and the supplier in another continent!, Which countries laws are superior and have to be observed?

Be patient, do not bad mouth your supplier in public places, it could be expensive!

as usual YMMV, IANAL



32  Hardware and U-Boot firmware / Hardware / Plug, (Sheeva or Guru) with mono LCD display. on: May 17, 2010, 07:54:55 AM

I was looking through my junk boxes,and came across a nice 320 x 240 pixel 5.7"  mono LCD module. This uses a built in SED1335 type controller.

Being  fed up with the doom and gloom regarding the Guruplug, and the looong wait for mine from NewIT, I thought I would try to use the display with my Sheevaplug to while away the hours.

I purchased a pre-programmed  PIC based controller from MPI, (www.angelfire.com/electronic/micropakindustries/index.html) and wired my LCD to the MPI S133X module.

The input to the controller is either normal serial  or high speed ascii, up to 1.5Mhz @ ttl levels and the command set is vast! for example  a command for drawing a XY graph is:-

  Text Command for Graph is:- AxxxyyyLDhhhwwwGTT

meaning of parameters

Starting Location upper left hand corner: xxx=<000:639>, yyy=<000:255>
Grid Style: L=<0:7>
0=No Grid
Pixel Type: D=<0:2>
1= Set
2= XOR
Y-Axis Length: hhh=<000:255>
X-Axis Length; www=<000:639>
Graph Type: G=<0:2>
0= 1st Quadrant
1= 1st/4th Quad.
2= 1/2/3/4 Quad
# of Pixels/Tic: TT=<00-99>
Default: 10 pixs/Tic
I have attached a picture of a weather station display demo provided with the MPIS module, running on my display.

My next step is to make a connection  to J6 or J7 in my Sheevaplug.  Since this is 3.3V logic I need to level change to 5V to and from the PIC controller.

I do not want to use a usb to async connection, I would prefer to leave my USB port free, and I am itching to try the internal async port on the Sheevaplug.

To drive the display from the Plug software. all I need is a small python script. to initialise the serial port and display, down load the "fixed" items in the display and then move the variable items to the various windows in the background.

The controller also has circuitry for a touch screen and a keypad. I have found a suitable cheap 4 wire touch screen on Ebay,  when I get this going then I can control and set up my applications using the touch screen.   I am thinking of environmental control apps, solar hot water control and logging, and weather monitoring. 

Of course these can be done solely by web interface, but its a bit of a pain to have to have a laptop or pc and monitor with you when you want to adjust the solar heat exchanger pump speed. or boot up a system to look at the temperature in the garden.   (There is nothing to stop me running a web display anyway, as a matter of routine, to display on my domain)

I will keep you posted on progress.




33  Hardware and U-Boot firmware / Hardware / Re: Power Plug rev 1.3 j6 uart and j7 on: May 17, 2010, 07:03:52 AM

I would like to use the currently unused serial uart connection in my "old" Sheevaplug V1.3.

This is the 4 pin header J6.  or the 6 pin header J7

I never found a BOM for the V1.3 Sheevaplug, so I do not know the mating cable connectors for J6 or J7

Please can anyone inform me of a suitable part?

If all else fails I will solder wires to the pins, but I will try to be tidy first!

Also has anyone succeeded in using this uart under Linux,  i.e. what device will it present?



34  General Category / General Discussion / Re: Sheevaplug info: wiki and FAQ on: May 06, 2010, 02:06:30 AM

The link ( http://plugcomputer.org/plugwiki/index.php/Special:WhatLinksHere/GuruPlug )

does NOT help fix the basic problem.

Try going into the wiki as a new Plug user, go to the main main, and then try to find the Guruplug,  I eventually found it by accident.  It is a hidden hot spot in the line

   Getting started

    * New Plugger How To: This page tells you how to connect to the plug.
    * Getting the Plug Computer Running with an Operating System: Will tell you how to boot the plug from the network or install another Linux or BSD distribution on the local solid state storage.
    * What happens during a routine boot.
    * The GuruPlug is here!

click on Guruplug and you get taken to the Guruplug page.

This item should be more prominent, mention the Guruplug page,  and be cross referenced in the left hand navigaion column



35  General Category / Application ideas and development Q/A / OpenMediaVault ---- (Open network attached storage system) on: May 05, 2010, 06:16:07 AM

This new project:-  http://blog.openmediavault.org/  is looking extremely good.  There are a lot of snap shots of the  management pages so far.

Volker, the person responsible for this new project was also the creator of FREENAS, however OMV is Linux based.

Although there is no mention of Sheevaplug,  he says that if you can install Debian , you can install OMV !

He has finished a lot of the bits, but so far he  is holding off from a release until he is comfortable with it.

I cannot find any reference to it already on this forum, so here you are!



36  General Category / General Discussion / Re: Sheevaplug info: wiki and FAQ on: May 04, 2010, 09:43:03 AM

Please, Please, Please

Will the wiki administrator fix the Wiki article hierarchy.

For example :-  http://plugcomputer.org/plugwiki/index.php/GuruPlug   

The  above Guruplug page  CANNOT, (AFAIK),  be reached  from any other page or the wiki main page.

It does not appear to be indexed anywhere.

This has been raised several times about other pages, but it has never been sorted out.

many thanks

37  Hardware and U-Boot firmware / Hardware / Re: Filesystem Backup Strategy on: May 03, 2010, 06:30:24 AM

I looked at this problem several years ago and at first I too thought I needed a RAID storage system, so I built one using 4 x 500GB Sata drives and a 4 tray hot swap unit, I put them into a m-itx case, lots of cutting and filing,  and drove it with a Via m-itx card. I use FREENAS as the operating system.  (Picture attached below).

After a few months I came to realize that the RAID system  (IN MY USAGE PATTERN)  was unnecessary, noisy and a power hog.

The reason for this is that I store large quantities of data that are only updated intermittently at long intervals. 

My data consists of Squeezeserver files (running under FREENAS) and photographic files.  There are also periodic backups (monthly) of my wife's and my Linux user home  folders.

So I normally use one one of the 4 500Gb drives on the NAS and when the data changes, ie new photos or a new CD to put on the Squeezeserver,  or weekly whichever is the shorter, if I add another gig of photos, I turn on another of the drives and let FREENAS do a Rsync update of the data to the second disk.   I then have TWO identical copies of data not more than a week stale.  I always check the target after adding data.

I suppose I should remove the second copy drive from the FREENAS and store it in another location but I am not that paranoid (yet).

I cannot emphasize enough the necessity for backups!!!!!!!!!

A couple of months ago a neighbour came to see me. She had given her daughter an old PC 3 years ago, and the daughter and her husband had used it constantly without backing it up.  One day the hard drive ceased to function.

They thought they had lost her husband's small business data, their household data, and ALL the pictures of their family and of their two children from birth till the drive crashed.

I was asked to try to recover the data.  Using a shareware Windoze disk recovery program, ($20) I found that the drive was still reading, but the directory structures had been destroyed.  After 10-12 nerve wracking hours, I managed to recover all the data, albeit with dummy file names. I stuck the files on a load of CD's and they put a new drive in their PC and reloaded and renamed all the files.

I received two bottles of wine for my effort not $500! They did pay for the recovery program.

I told them to back their data up in future, but I wonder whether they really are doing it or whether we will be going through this excerise again some day!

As usual YMMV



edit replaced picture with a resized version kindly creaed by jlPoole.
38  General Category / General Discussion / GuruPlug U-Snap Interface --- Any Use? on: April 29, 2010, 03:07:25 AM

In preparation for the delivery of my Guru+, I have been reading up on it's features, one of which is the U-Snap port.

The U-Snap alliance has a website:-  www.usnap.org

The port is designed for  (according to the website) :-

U-SNAP (Utility Smart Network Access Port) is a utility industry initiative whose primary objective is to create a low-cost protocol-agnostic, interoperable communications card standard for connecting HAN (Home Area Network) devices to Smart Meters.

This standard resembles the popular USB standard for attaching hardware devices in a computer. U-SNAP defines a standard connector, PCB interface and serial interface enabling consumer products to support a variety of communication protocols.

The physical iteration of the port (or connector) is:-

The U-SNAP interface connector consists of a 10 pin, 2mm pin header. This supports a 2mm receptacle, Harwin Part Number M22-7131042 or equivalent. The current U-SNAP connector supports 10 pins in the following configuration:

Pin    Signal
1    24VAC Return
2    24VAC Common
3    SELECT*, must be held high when not communicating with UCD
5    SCLK
6    MOSI
7    MISO
8    RESET*
9    +3.3V Power
10    Signal Ground
11    Reserved (Factory Test)
12    Reserved (Factory Test)

 24VAC !!!!   On a Guruplug ??

From the Faq, it also shows that they expect that the added value interface card will be plugged directly into the fixed connector port of the Guru plug as a "piggy back" card

For those not familiar with it, the U-Snap connection uses  an SPI interface:-


A Serial Peripheral Interface (SPI) system consists of one master device and one or more slave devices. The
master is defined as a microcontroller providing the SPI clock and the slave as any integrated circuit receiving
the SPI clock from the master. The ASIC in VTI Technologies’ products always operates as a slave device in
master-slave operation mode.
The SPI has a 4-wire synchronous serial interface. Data communication is enabled with a low active Slave
Select or Chip Select wire (CSB). Data is transmitted with a 3-wire interface consisting of wires for serial data
input (MOSI), serial data output (MISO) and serial clock (SCK).

I cannot find a proper physical layer spec for an SPI bus, according to one website I visited, every chip vendor publishes their own ideas of specs of the physical bus structure, length, speed etc, to suit their own chips.  From what I can see it was designed as an inter-i.c. on ONE BOARD system, so I do not know how far and successfully one could drive it from the Guruplug  via  a cable to another device. 

I suppose that one could fit long line drivers in a cable end plug body that actually plugs into the U-Snap port.

Here is a very good article on Linux suport:-


I do not need an intelligent meter connected to my Guruplug, I get on fine with my CurrentCost CC128, and Dale's excellent logging and display program!

 However one application I am interested in is the possible use of an SPI - LCD interface, see :-


I am sure that there are lots of devices that can usefully be hung onto a Guruplug SPI bus!



39  General Category / General Discussion / Re: Guruplug Server Plus built-in serial port? on: April 29, 2010, 02:24:55 AM


I just had a look at the schematics for the Guru,  the only  serial I can find is connector J7, a four pin connector with RXD on pin 2 and TXD on pin 3, but no control signals.

I must have missed the async serial port, please can you tell me what is the connector designation, and what sheet of the schematics I can find it on?.

I could use a serial port in my project!

Many thanks

40  Hardware and U-Boot firmware / Hardware / Re: Prolific Driver for Currentcost device on: March 15, 2010, 02:30:11 AM

You can just install the driver module if it is available in your system.

You may find that the Prolific driver is already compiled as a module  (pl2303.ko)  If so it will be in your plug's  modules directory. It  should be in  /lib/modules/"kernel-name"/kernel/drivers/usb/serial/pl2303.ko.   where kernel-name is the current kernel you are booting.

Check kernel version with uname -a

You can then install the driver by doing a modprobe or insmod  ( use man modprobe or man insmod for help!)

After installing check the  module is present with lsmod

If the pl2303.ko module is not in your modules directory, you can add a modules directory  containing the prolific driver to your system from another repository.  You can ONLY add a directory  with  the SAME kernel version as your kernel version (major and minor). Do NOT mix versions, it won't work.


41  Hardware and U-Boot firmware / Hardware / Re: Prolific Driver for Currentcost device on: March 14, 2010, 12:22:04 PM

It is some time since I experimented with my current cost CC128 power monitor on the Sheeva Plug.

but if I remember correctly,  when I had to compile a new kernel for the Plug,  for my sata mods,  I also had to change the  config to include the Prolific driver in the USB section. 

It all worked OK after that. ( running  xpl-perl and the cc128 module)


42  General Category / General Discussion / Re: New QT based installer: Enhanced Sheevaplug Installer Application (ESIA) on: March 04, 2010, 08:12:19 AM
Hi rooster

I have installed ESIA on Debian squeeze, and read several times the "quick start" guide.

It appears very complex to set up the files to burn to the Sheevaplug.

By the look and feel of ESIA  it was intended for S/W retailers to sell down loadable apps to run on a customers Sheevplug with remote purchase.

Regarding the ESIA app itself.

1. I cannot get the Device page to display any info on my plug, it can "see" it but all the details are N/A. Does this work yet?

2.  Reading the instructions, it seems that I HAVE to install a USB stick on the Sheevaplug on all operations, even if I am loading  a kernel from a "web" address.   The sheeva plug has to load  something from the USB stick that enables it to d/l from an IP address      HOW? WHY?  If the final D/L fails, does the plug get restored to the original state?

3.  How can I set load addresses for the down loadable information.  i.e. how do I set parameters?

4. Can I  build systems on SD and USB sticks or is  ESIA limited to D/L to nand?

5. If I just want to reload a new uboot.bin, where do I put it?  Do I need to build the complete "app" directory

6. Can this do a "bare iron" re-install or does the Plug have to be running a system?

7. Why can't the ESIA generate the md5 checksums, instead of the user having to do it?



43  General Category / General Discussion / Re: Please change the forum color scheme ! on: March 01, 2010, 02:28:35 AM

Why don't you change it yourself!

It will always come up in your chosen colours whenever you log in

(You have already set up an account to be able to post your query)


44  Hardware and U-Boot firmware / Hardware / Re: SheevaPlug USB Power Supply problems. Can it Drive a USB Ext Disk? on: February 19, 2010, 03:40:20 AM


I don't think an occasional spinup 1000 ma is going to be a problem.

I think the problem is constantly varying dc load plus maybe a high overall current requirement and finally perhaps elevated temperature in the unvented metal ps enclosure in the Sheevaplug base.

The ripple current varies as the dc load on the power supply.  During the conducting period of the bridge rectifier, the cap is charged up, and the bridge rect supplies BOTH the charge current and the current for the dc load. During the "off" period of the bridge rectifier, the cap has to provide the dc power for the load, as the charge is used in the cap the voltage across the cap decreases. On the next conducting period of the bridge the cap recharges. Obviously the greater the current drawn, the more "ripple" current is generated.

I will dig out a couple of 10w  0.1 ohm resistors from my parts box, and wire them into the 5v output  and do some 'scope measurements of the current amplitude and waveforms. I will also try to measure the operating temperature inside the power supply case, if I can get my remote temp probe into it.



45  Hardware and U-Boot firmware / Hardware / SheevaPlug USB Power Supply problems. Can it Drive a USB Ext Disk? on: February 18, 2010, 01:50:28 PM
In the Hardware thread, "is my shaevaplug dead", http://plugcomputer.org/plugforum/index.php?topic=1318.0, there are two or maybe three users who appear to have a broken sheevaplug  internal  mains to 5V power supply unit.

The common theme in these faults appears to be connecting  and running an external USB 2.5in disk drive that is drawing it's 5V supply via the sheevaplug's USB connecter.

Looking at the pictures of one of the blow ups, it appears that C1, a 6.8ufd 400v electrolytic capacitor dumped its electrolyte into the supply. This capacitor is connected across the o/p of the full wave bridge rectifier (4 diodes) that rectifies the incoming ac mains voltage.

Now a digression on electrolytic capacitors.  (Wikipedia has a full explanation for enquiring minds)

In the theoretical  world, a capacitor consists of two plates and an 100% insulating dialectric. In the real world,  the dialectric has a dc leakage resistance and an ac leakage impedance. This impedance is composed of a reactive and resistive component. The in phase resistive component is called the "Equivalent Series Resistance" (ESR).

 The ac component in the current flowing in the capacitor, is caused by the ripple on the dc current. If the capacitor is drawing a CONSTANT current, there is only the ripple current is the charging part of the cycle when the  mains bridge conducts and charges the capacitor, and the constant load discharges it to the mean value. However if the output of the capacitor is connected to a rapidly changing load, then the ripple can assume a large percentage of the total supplied current. 

The ripple current is converted to heat (Irip^2 x ESR = watts) and this causes the electrolyte to heat.  When the electrolyte heats the ESR increases and the capacitor can go into thermal runaway. To stop the capacitor exploding violently the top of the capacitor is scribed in a cross, as a deliberate weak point.  Capacitors that are on the way to self distruction sometimes bulge the  flat end out into a dome instead of a flat before they vent.

To prevent this, capacitors that are going to be used in a power supply or high ripple environment ( audio amps etc), are normally carefully chosen for a low ESR and a high nominal operating temperature.

There are also stories that many manufacturers used a "magic" formula from another manufacturer and got it wrong, and made the ESR problem worse. PC motherboards have suffered from electrolytic cap failure for several years, and if you Google for motherboard cpacitors you will find dozens of sites talking about it and the replacement caps procedure.

Returning to the Sheevaplug power supply.

I was worried about these failures so I stripped the power supply out of my  sheeva plug and had a look at the manufacturer and type of capacitor used.   I found the two main electrolytics were Chinese in origin, Yalecon RX 400V, 105 deg C devices.   I searched vainly for a proper specification for these capacitors. All I found was a one line buying spec from one of the Chinese sales factors. The capacitors are manufactured by  Gagaku Yiyang Electronics Co,and have the following characteristics (Example RX only):-

Brand     Domestic      Model      RX
 Dielectric    Aluminum    Applications  Filter
Profile    Cylindrical    Power characteristics     Power
Frequency    HF     Adjusting Fix
Lead Type    In the same direction pinout    Tolerance    ± 20 (%)
Withstand voltage    500 (V) Nominal Capacity    68UF
Loss    5.0

The USB V 2.0 spec defines that the host shall supply up to 0.5A at 5V per port.

A typical 2.5in 500GB hard disk drive spec, my Samsung HM500L1 states the power consumption is:-
Power Requirements:
- Voltage: +5V+/-5%
- Spin-up Current (Max.): 1000 mA
- Seek (typical): 2.6 W
- Read/Write (typical): 2.3 W
- Low Power Idle(typical): 0.6 W
- Standby(typical): 0.25 W
- Sleep(typical): 0.2 W

So on idle its using 0.6W = 0.12A,  but when seeking it uses 2.6W or 0.52 A

Depending on HOW MUCH FILTERING is in the external enclosure, the drive is going to create some or a lot of ac ripple in the Sheevaplug 5V supply.

This is ignoring the ripple of the sheevaplug SOC's  own  current consumption variations

The other problem is that the capacitors are "domestic" rated at 105 deg C max.   There are higher quality devices on the market rated at 130 deg C.

I have NO knowledge what the internal operating temperature of the Sheevaplug power supply is when it is drawing a heavy load.

Also I have NO idea what the design output current for the Sheevaplug power supply is.

Therefore I would recommend that you power your USB hard drive enclosures from a separate +5v wall wart or brick


If you don't know the normal HV safety rules then you should not be into a mains switcher!





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