I have a project that required me to programmatically control power to several devices. I have done this before using a
Velleman vm8090 board which is relatively easy to control. However they are relatively expensive.
I turned to ebay and found a
similar module at a substantially reduced cost. Upon receipt however I discovered that instead of being a simple serial USB interface it presented
USB HID and the Debian system I was running it on has loaded the hiddev driver for me but it did not implement any of the standard
HID Usage Pages leaving me with no way to control the device.
I did the obligatory
sudo lsusb -d 12bf:ff03 -vvv
Bus 003 Device 019: ID 12bf:ff03
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x12bf
idProduct 0xff03
bcdDevice 1.00
iManufacturer 1 Matrix Multimedia Ltd.
iProduct 2 Flowcode USB HID
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 41
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 50mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 0 No Subclass
bInterfaceProtocol 0 None
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.10
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 54
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 5
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x01 EP 1 OUT
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 5
Device Status: 0x0980
(Bus Powered)
This simply showed me what I already knew and surprised me that lsusb did not dump HID report descriptor items. Some searching revealed that teh device had to be unbound so lussb could access the descriptor.
Thus a simple
echo -n 3-1.1.4:1.0 sudo dd of=/sys/bus/usb/drivers/usbhid/unbind
resulted in lussb dumping the descriptor items:
Item(Global): Usage Page, data= [ 0xa0 0xff ] 65440
(null)
Item(Local ): Usage, data= [ 0x01 ] 1
(null)
Item(Main ): Collection, data= [ 0x01 ] 1
Application
Item(Local ): Usage, data= [ 0x02 ] 2
(null)
Item(Main ): Collection, data= [ 0x00 ] 0
Physical
Item(Global): Usage Page, data= [ 0xa1 0xff ] 65441
(null)
Item(Local ): Usage, data= [ 0x03 ] 3
(null)
Item(Local ): Usage, data= [ 0x04 ] 4
(null)
Item(Global): Logical Minimum, data= [ 0x00 ] 0
Item(Global): Logical Maximum, data= [ 0xff 0x00 ] 255
Item(Global): Physical Minimum, data= [ 0x00 ] 0
Item(Global): Physical Maximum, data= [ 0xff ] 255
Item(Global): Report Size, data= [ 0x08 ] 8
Item(Global): Report Count, data= [ 0x08 ] 8
Item(Main ): Input, data= [ 0x02 ] 2
Data Variable Absolute No_Wrap Linear
Preferred_State No_Null_Position Non_Volatile Bitfield
Item(Local ): Usage, data= [ 0x05 ] 5
(null)
Item(Local ): Usage, data= [ 0x06 ] 6
(null)
Item(Global): Logical Minimum, data= [ 0x00 ] 0
Item(Global): Logical Maximum, data= [ 0xff 0x00 ] 255
Item(Global): Physical Minimum, data= [ 0x00 ] 0
Item(Global): Physical Maximum, data= [ 0xff ] 255
Item(Global): Report Size, data= [ 0x08 ] 8
Item(Global): Report Count, data= [ 0x08 ] 8
Item(Main ): Output, data= [ 0x02 ] 2
Data Variable Absolute No_Wrap Linear
Preferred_State No_Null_Position Non_Volatile Bitfield
Item(Main ): End Collection, data=none
Item(Main ): End Collection, data=none
By consulting the
device class definitions document I determined the device was using the "Vendor defined" Usage page (0xff00 to 0xffff) so I would definitely have to write a program to control the device.
Linux provides a really easy interface to deal with HID devices called hiddev (gosh, such adventurous naming) which I already had to unbind to get my descriptors decoded so I am fairly sure it works ;-)
The kernel
documentation and
header for hiddev provide the absolute basic mechanics of the interface but no example code or guidance. The obligatory web search turned up
very little and even that had to be retrieved from the internet archive. So It seems I would be forced to work it through myself.
It seems the hiddev interface is orientated around HID devices generating reports which the program is expected to read. Numerous ioctl() are provided so the program can obtain the descriptor information necessary to control and process the received reports.
However in this case we need to be able to send reports to the device, all the descriptor information revealed was that there were eight (Item Report Count = 8) values with eight bits each (Item Report Size = 8) with logical and physical values representing the whole range of the octets.
Fortunately the seller provided a
website with some control programs and even source. After some time rummaging through the Visual Basic program I finally found (in FrmMain.vb:2989) that the eight bytes were largely unused and the first was simply a bitmask of the eight relays coil status, set for energised clear for off. With bit 0 controlling relay labelled 1 through to bit 7 for relay 8.
To send a report to a HID device the hiddev interface uses the HIDIOCSREPORT ioctl where the report data is first set using HIDIOCSUSAGE .
The HIDIOCSUSAGE ioctl is passed a hiddev_usage_ref structure which must be initialised with information about the report descriptor identifier (constructed from the Usage Page and Usage as set by the items in the descriptor), the index of the item (named usage) we wish to set in the report (in this case the first which is 0) and the value we actually want to set.
After a great deal of debugging the final program is
very short indeed but does the job, my main problem now is that if I switch too many (more than one) relays at once the whole device resets. The scope says the supply rails are behaving very badly when this happens, looks like I need to add a load of capacitance to the power well to stabilise it during the switching events.
Oh and add in the fact Relay 1 LED doest work unless you push on it and I do wonder about the wisdom of the economy in this case. Though yet again Linux makes the software side easy.
This week, I accepted a job on the faculty of at the University of
Washington Department of Communication. I've arranged for a
post-doc during the 2013-2014 academic year which I will spend at UW
as an Acting Assistant Professor. I'll start the tenure-track
Assistant Professor position in September 2014. The hire is part of a
"big data" push across UW. I will be setting up a lab and research
projects, as well as easing into a teaching program, over the next
couple years.
I'm not going to try to list all the great people in the department,
but UW Communication has an incredible faculty with a strong
background in studying the effect of communication technology on
society, looking at political communication, enagement, and collective
action, and tracing out the implications of new communication
technologies in addition to very strong work in other areas. Years
ago, I nearly joined the department as a graduate student. I am
unbelievably happy that their faculty has invited me to join as a
colleague.
Outside of my new department, the University of Washington has a
superb group of folks working across the school on issues of
quantitative and computational social science, human-computer
interaction, and computer-supported cooperative work. They are
hiring a whole bunch of folks, across the university, who specialize
in data-driven social science. I already have a bunch of relationships
with UW faculty and students and am looking forward to expanding and
deepening those.
On a personal level, Mika and I are also very excited to return to
Seattle. I grew up in the city and I've missed it, deeply, since I
left now nearly half my lifetime ago! It will be wonderful to be
much closer to many of my family members.
But I know that I will miss the community of friends and colleagues
that I've built in Boston over the last 7+ years just as deeply. I'm
going to miss the intellectual resources, and the intellectual
community, that folks in Cambridge get to take for granted. That said,
I plan to maintain affiliations and collaborations with folks at
Harvard and MIT and will have resources that let me spend time in
Boston doing that.
If you are curious what I'm going to be up to and what the future is
likely to hold in terms of my research you should check the material
I've put online as part of the job market this year. I've posted just
about everything on my academic website. This includes a little
four page research statement which describes the work I've done and
the directions I've been thinking about taking it.
The academic job market is challenging and confusing. But it's given
me a lot of opportunity to reflect, at length, on both the substance
of my research and the academy and its structures and processes. I've
got a list of blog topics queued up based on that thinking. I'll be
posting them here on my blog over the next few months.
What happens if the same person (in this case, my girlfriend) is both a bit geeky and likes to bake? She has ideas leading to this:
A long time ago, I spent many many hours playing Frontier (Elite 2) on
the family Atari ST. It was nice-looking (oh, those sunrises on
distant planets!), playable, varied, had ample room for progression,
very different possible roles, a huge universe of which nobody could
ever hope of exploring more than a tiny fraction, and it was basically
the first game I encountered with no set goals. You are a spaceship
pilot in a galaxy colonised left and right, and it's up to you to
decide what you want the game to be. Pirate, headhunter, mercenary,
trader, taxi, explorer, there's no end goal to achieve except what you
fix for yourself. That was, for me as a youngster, a mind-opening
experience, which I never felt as strongly since (with the possible
exception of the Creatures game, but I barely tried it).
Then came modernity, the PC, and the First Encounters sequel
(Elite 3). It added moderate complexity to the gameplay, some sort of
political evolution among the factions and a kind of plot so the
galaxy was no longer quite so static, but the end results were still a
bit disappointing. It felt like Frontier with a few
not-exactly-overwhelming textures stuck onto the ships, a loose plot
arc, and a third faction, the Alliance of Independent Systems, beyond
the Federation and the Empire. Not that exciting, although the name
of the Alliance's capital star system stayed in my mind.
So, like many others, I came to wait for Elite 4. That wait started
in 1995, more than seventeen years ago. During that time, Duke Nukem
Forever was announced, promised, developed, postponed, abandoned,
found again, developed again, and it was even actually released in
2011, while Elite 4 went into the same kind of hell only without the
actual release (yet).
At some point I started trying various substitutes to help pass time.
There was Parsec which was a nice-looking space combat simulator,
multiplayer and all, but never felt like finished. Development slowed
down to a thin trickle, and it seems like it only recently started
again as 
I started using LastFM probably around 6 years ago, and loved its offering. I discovered a huge amount of music I would have never found otherwise.
Then, some time later, it changed its terms of use, and those of us not in some selected countries lost the ability to stream them for free. Bummer.
About one year ago, I decided to purchase a subscription. After all, getting to know new music is always good And listening to recommendations for friends with interesting music tastes is fun as well!
Of my last music purchases, both in CD and as MP3 downloads (not a spectacular volume, probably some 15 albums in the last year), I can only point to two that I knew the interpreter beforehand. So, we could say I have bought approx. 1 album per month completely thanks to LastFM.
But, as of January 15, they are changing their licensing terms, and LastFM streaming service will no longer be available in Mexico. All it will continue to give me is recommendations based on my listening habits, given I continue "scrobbling" - Much less useful, not to say completely useless given my usual patterns.
So, I'm sadly cancelling my subscription, and quite probably will stop using the service altogether. And yes, this will make me reevaluate freely licensed music services. But while I know of several free music distribution sites such as Jamendo, I will long for this LastFM abililty to deliver me music that is aligned to my current tastes (instead of looking them up by myself)
Any suggestions on where to look for a similar service?
Yeah, wait, what?
No, really!
I took a look through 
I'm taking a krav maga class. It seems like a good place for single guys to meet women, she hinted.
Oh, good god, he sighed. Classes are a girl's last resort.
I'm taking it with Bev, she continued.
Is she the hot one? he asked.
Second eldest, she clarified.
See? he crowed. Classes are a girl's last resort.
Have you ever heard someone talking extensively about Cloud Computing or generally Clouds? and have you ever noticed the fact many people (even the ones who present themselves as experts) don t really understand what a Cloud is at all? That happened to me multiple times and one of the most common misunderstandings is many see the Cloud as something being on the internet. Many companies add a little logo representing a cloud on their frontpage and without a single change on their infrastructure (but surely with a price increment) they start calling their products as being on the Cloud. Given the lack of knowledge about this specific topic people tend to buy the product presented as being on the Cloud without understanding what they really bought.
But what Cloud Computing really means? it took several years and more than fifteen drafts to the National Institute of Standards and Technology s (NIST) to find a definition. The final accepted proposal:
This is the listing for my local cross-build-only repository for perl:
With immediate effect, 
While setting a puppet agent to talk to my puppetmaster I ve got this weird SSL error:
After several months, my patches for 