I'm sorting out how to achieve the following, I want to use smart or memory cards in a project. The cards should be read by standardized card readers (for example ACR38). When they are read by the computer ( command line or by a software (processing or p5js or similar), there should be a popup a window which shows the contents of the card being a picture and a text. Bit similar when I use my regular ID to be read by my E-idsoftware.
For the moment the card I have is this one SLE4428 (at the bottom instructions from the vendor)
These have no data on it yet and are bought blank
=> datasheet
The software I found but don't know if it's suited for my project and how to specifically use it is the following.
Opensource tools that I found when searching for SC cards software (no id how to use them.)
https://linux.die.net/man/1/opensc-tool
https://linux.die.net/man/1/opensc-explorer
I looked at my smartcard reader and found that http://www.acr38u.com/
is a platform but has to be payed for and I'm unable to found sofware for this on linux or apple.
Again here I found a datasheet with hex code to connect to the card, but still not how to physically connect to the cards.
This site shows many points of a working shell but I can't find the installer for it. opendsc
Then lastly this is the most promising and I already contacted the maker of it. But installation gets stuck in the make process (which I've already searched for and is not solution yet, being at it for a week now so therefore this post, maybe the community can help with an alternative look)
This is the explanation from the vendor side (Aliexpress) which is kind of specific. Though I don't know where to input these hex codes to write or read from the card. (there is a software but it's windows (If there is somebody that can say, that the way to solve the core question of my project then I'll try to get a windows pc to work on it via that way))
ISO7816 SLE 4442 Chip PVC Contact Smart Card (0.8* 85.5 * 54mm)
If you need write the 4442 cards,you should buy the contact smart reader writer!! 4442 cards not support 13.56mhz rfid writer!!!
NOTE:There is NO magnetic strip behind the card.
Graphics Quality Cards For All Photo ID Card Printers Including
DataCard, Zebra, Fargo, Evolis, Magicard, NBS & etc.
(These Cards Will Not Work In Inkjet Printers)
If you need 100pcs 4442 cards,pls check the links below:
[https://www.aliexpress.com/store/product/100-pcs-lot-ISO7816-RFID-Contact-SLE-4442-Chip-PVC-Smart-Card/516120_32425491077.html?spm=2114.12010608.0.0.R0bzFx][1]
Features:
Standard:ISO7816
Product Chip:SLE4442
Color:White
Dimension: L 85.5 x W 54 x H 0.80±0.04mm
256 × 8-bit EEPROM organization
32 × 1-bit organization of protection memory
erase cycles more than 100,000 times
Data retention for minimum of ten years
Default passwords: FFFFFF
3 bytes for error counter and card secret code area
1,Write protected area (first 32 bytes) of each byte can be individually write protected, After write,the data can't be changed.
2, Before checking the password, all the data can be read, if necessary,you could encryption data.
3, After confirm password is correct,the data could be write or modify.
4, The 3 bytes of user passwords, after confirm is correct,it could be change.
5, The password error counter, the initial value of 3, check the error code 1, then subtract 1, if the counter value is 0, the card is automatically locked, the data just read out, no longer change can no longer be password verification; if zero, the one time password verification is correct, restore to the initial value.
6, The byte address 0-5,6-7 factory prior written by the manufacturers can not be changed.
The specifics for this question lies in either
A: How can I achieve a working environment on linux or mac (first) to read and write data on an sc card (the one I have or !B: a working alternative)
C: Create a viewer program or webapp, etc.. to view or route the data to when the SC card is being read. (This would be a valid question, If i where to chose a Windows based existing program, I think)
Because this is not code specific, but I still want people that have the same questions to be able to see this page to show them pletora of scripts and ways to approach this or similar SC project.
This guy knows a lot about OpenSC!
Trying to get access to a partially rooted Galaxy S2 external sd card.
The problem is that /dev/block/mmcblk1p1 does not exist on the phone. This is the device name that should allow me to put the "recovery" image onto the sdcard so that the unit will be a phone again.
Problem is, I don't know where to find the magic Major and Minor numbers for this device and I'm trying to figure out where in the kernel source I should be looking for them.
Could someone point me at the right kernel files to find this information?
Standard devices use predefined major numbers and minor numbers starting from 0 for the first instance and upward depending on how many instances there are going to be.
Look at the Linux Documentation file(devices.txt) to see the full list but the section of interest to you is:
179 block MMC block devices
0 = /dev/mmcblk0 First SD/MMC card
1 = /dev/mmcblk0p1 First partition on first MMC card
8 = /dev/mmcblk1 Second SD/MMC card
...
The start of next SD/MMC card can be configured with
CONFIG_MMC_BLOCK_MINORS, or overridden at boot/modprobe
time using the mmcblk.perdev_minors option. That would
bump the offset between each card to be the configured
value instead of the default 8.
So /dev/block/mmcblk1p1 would be major 179, minor 9.
According to hotplug.txt
Entries for block devices are found at the following locations:
/sys/block/*/dev
/sys/block/*/*/dev
So try looking in /sys/block/mmcblk1p1/dev.
EDIT:
Looking at it again I actually think that it will be in /sys/block/mmcblk1/mmcblk1p1/dev
Sorry for the wall of text - TL;DR:
What is the framerate of VNC connection (in frames/sec) - or rather, who determines it: client or server?
Any other suggestions for desktop screen capture - but "correctly timecoded"/ with unjittered framerate (with a stable period); and with possibility to obtain it as uncompressed (or lossless) image sequence?
Briefly - I have a typical problem that I am faced with: I sometimes develop hardware, and want to record a video that shows both commands entered on the PC ('desktop capture'), and responses of the hardware ('live video'). A chunk of an intro follows, before I get to the specific detail(s).
Intro/Context
My strategy, for now, is to use a video camera to record the process of hardware testing (as 'live' video) - and do a desktop capture at the same time. The video camera produces a 29.97 (30) FPS MPEG-2 .AVI video; and I want to get the desktop capture as an image sequence of PNGs at the same frame rate as the video. The idea, then, would be: if the frame rate of the two videos is the same; then I could simply
align the time of start of the desktop capture, with the matching point in the 'live' video
Set up a picture-in-picture, where a scaled down version of the desktop capture is put - as overlay - on top of the 'live' video
(where a portion of the screen on the 'live' video, serves as a visual sync source with the 'desktop capture' overlay)
Export a 'final' combined video, compressed appropriately for the Internet
In principle, I guess one could use a command line tool like ffmpeg for this process; however I would prefer to use a GUI for finding the alignment start point for the two videos.
Eventually, what I also want to achieve, is to preserve maximum quality when exporting the 'final' video: the 'live' video is already compressed when out of the camera, which means additional degradation when it passes through the Theora .ogv codec - which is why I'd like to keep the original videos, and use something like a command line to generate a 'final' video anew, if a different compression/resolution is required. This is also why I like to have the 'desktop capture' video as a PNG sequence (although I guess any uncompressed format would do): I take measures to 'adjust' the desktop, so there aren't many gradients, and lossless encoding (i.e. PNG) would be appropriate.
Desktop capture options
Well, there are many troubles in this process under Ubuntu Lucid, which I currently use (and you can read about some of my ordeals in 10.04: Video overlay/composite editing with Theora ogv - Ubuntu Forums). However, one of the crucial problems is the assumption, that the frame rate of the two incoming videos is equal - in reality, usually the desktop capture is of a lower framerate; and even worse, very often frames are out of sync.
This, then, requires the hassle of sitting in front of a video editor, and manually cutting and editing less-than-a-second clips on frame level - requiring hours of work for what will be in the end a 5 minute video. On the other hand, if the two videos ('live' and 'capture') did have the same framerate and sync: in principle, you wouldn't need more than a couple of minutes for finding the start sync point in a video editor - and the rest of the 'merged' video processing could be handled by a single command line. Which is why, in this post, I would like to focus on the desktop capture part.
As far as I can see, there are only few viable (as opposed to 5 Ways to Screencast Your Linux Desktop) alternatives for desktop capture in Linux / Ubuntu (note, I typically use a laptop as target for desktop capturing):
Have your target PC (laptop) clone the desktop on its VGA output; use a VGA-to-composite or VGA-to-S-video hardware to obtain a video signal from VGA; use video capture card on a different PC to grab video
Use recordMyDesktop on the target PC
Set up a VNC server (vino on Ubuntu; or vncserver) on the target PC to be captured; use VNC capture software (such as vncrec) on a different PC to grab/record the VNC stream (which can, subsequently, be converted to video).
Use ffmpeg with x11grab option
*(use some tool on the target PC, that would do a DMA transfer of a desktop image frame directly - from the graphics card frame buffer memory, to the network adapter memory)
Please note that the usefulness of the above approaches are limited by my context of use: the target PC that I want to capture, typically runs software (utilizing the tested hardware) that moves around massive ammounts of data; best you could say about describing such a system is "barely stable" :) I'd guess this is similar to problems gamers face, when wanting to obtain a video capture of a demanding game. And as soon as I start using something like recordMyDesktop, which also uses quite a bit of resources and wants to capture on the local hard disk - I immediately get severe kernel crashes (often with no vmcore generated).
So, in my context, I typically do assume involvement of a second computer - to run the capture and recording of the 'target' PC desktop. Other than that, the pros and cons I can see so far with the above options, are included below.
(Desktop preparation)
For all of the methods discussed below, I tend to "prepare" the desktop beforehand:
Remove desktop backgrounds and icons
Set the resolution down to 800x600 via System/Preferences/Monitors (gnome-desktop-properties)
Change color depth down to 16 bpp (using xdpyinfo | grep "of root" to check)
... in order to minimize the load on desktop capture software. Note that changing color depth on Ubuntu requires changes to xorg.conf; however, "No xorg.conf (is) found in /etc/X11 (Ubuntu 10.04)" - so you may need to run sudo Xorg -configure first.
In order to keep graphics resource use low, also I usually had compiz disabled - or rather, I'd have 'System/Preferences/Appearance/Visual Effects' set to "None". However, after I tried enabling compiz by setting 'Visual Effects' to "Normal" (which doesn't get saved), I can notice windows on the LCD screen are redrawn much faster; so I keep it like this, also for desktop capture. I find this a bit strange: how could more effects cause a faster screen refresh? It doesn't look like it's due to a proprietary driver (the card is "Intel Corporation N10 Family Integrated Graphics Controller", and no proprietary driver option is given by Ubuntu upon switch to compiz) - although, it could be that all the blurring and effects just cheat my eyes :) ).
Cloning VGA
Well, this is the most expencive option (as it requires additional purchase of not just one, but two pieces of hardware: VGA converter, and video capture card); and applicable mostly to laptops (which have both a screen + additional VGA output - for desktops one may also have to invest in an additional graphics card, or a VGA cloning hardware).
However, it is also the only option that requires no additional software of the target PC whatsoever (and thus uses 0% processing power of the target CPU) - AND also the only one that will give a video with a true, unjittered framerate of 30 fps (as it is performed by separate hardware - although, with the assumption that clock domains misalignment, present between individual hardware pieces, is negligible).
Actually, as I already own something like a capture card, I have already invested in a VGA converter - in expectation that it will eventually allow me to produce final "merged" videos with only 5 mins of looking for alignment point, and a single command line; but I am yet to see whether this process will work as intended. I'm also wandering how possible it will be to capture desktop as uncompressed video # 800x600, 30 fps.
recordMyDesktop
Well, if you run recordMyDesktop without any arguments - it starts first with capturing (what looks like) raw image data, in a folder like /tmp/rMD-session-7247; and after you press Ctrl-C to interrupt it, it will encode this raw image data into an .ogv. Obviously, grabbing large image data on the same hard disk as my test software (which also moves large ammounts of data), is usually a cause for an instacrash :)
Hence, what I tried doing is to setup Samba to share a drive on the network; then on the target PC, I'd connect to this drive - and instruct recordMyDesktop to use this network drive (via gvfs) as its temporary files location:
recordmydesktop --workdir /home/user/.gvfs/test\ on\ 192.168.1.100/capture/ --no-sound --quick-subsampling --fps 30 --overwrite -o capture.ogv
Note that, while this command will use the network location for temporary files (and thus makes it possible for recordMyDesktop to run in parallel with my software) - as soon as you hit Ctrl-C, it will start encoding and saving capture.ogv directly on the local hard drive of the target (though, at that point, I don't really care :) )
First of my nags with recordMyDesktop is that you cannot instruct it to keep the temporary files, and avoid encoding them, on end: you can use Ctrl+Alt+p for pause - or you can hit Ctrl-C quickly after the first one, to cause it to crash; which will then leave the temporary files (if you don't hit Ctrl-C quickly enough the second time, the program will "Cleanning up cache..."). You can then run, say:
recordmydesktop --rescue /home/user/.gvfs/test\ on\ 192.168.1.100/capture/rMD-session-7247/
... in order to convert the raw temporary data. However, more often than not, recordMyDesktop will itself segfault in the midst of performing this "rescue". Although, the reason why I want to keep the temp files, is to have the uncompressed source for the picture-in-picture montage. Note that the "--on-the-fly-encoding" will avoid using temp files altogether - at the expence of using more CPU processing power (which, for me, again is cause for crashes.)
Then, there is the framerate - obviously, you can set requested framerate using the '--fps N' option; however, that is no guarantee that you will actually obtain that framerate; for instance, I'd get:
recordmydesktop --fps 25
...
Saved 2983 frames in a total of 6023 requests
...
... for a capture with my test software running; which means that the actually achieved rate is more like 25*2983/6032 = 12.3632 fps!
Obviously, frames are dropped - and mostly that shows as video playback is too fast. However, if I lower the requested fps to 12 - then according to saved/total reports, I achieve something like 11 fps; and in this case, video playback doesn't look 'sped up'. And I still haven't tried aligning such a capture with a live video - so I have no idea if those frames that actually have been saved, also have an accurate timestamp.
VNC capture
The VNC capture, for me, consists of running a VNC server on the 'target' PC, and running vncrec (twibright edition) on the 'recorder' PC. As VNC server, I use vino, which is "System/Preferences/Remote Desktop (Preferences)". And apparently, even if vino configuration may not be the easiest thing to manage, vino as a server seems not too taxing to the 'target' PC; as I haven't experienced crashes when it runs in parallel with my test software.
On the other hand, when vncrec is capturing on the 'recorder' PC, it also raises a window showing you the 'target' desktop as it is seen in 'realtime'; when there are large updates (i.e. whole windows moving) on the 'target' - one can, quite visibly, see problems with the update/refresh rate on the 'recorder'. But, for only small updates (i.e. just a cursor moving on a static background), things seem OK.
This makes me wonder about one of my primary questions with this post - what is it, that sets the framerate in a VNC connection?
I haven't found a clear answer to this, but from bits and pieces of info (see refs below), I gather that:
The VNC server simply sends changes (screen changes + clicks etc) as fast as it can, when it receives them ; limited by the max network bandwidth that is available to the server
The VNC client receives those change events delayed and jittered by the network connection, and attempts to reconstruct the desktop "video" stream, again as fast as it can
... which means, one cannot state anything in terms of a stable, periodic frame rate (as in video).
As far as vncrec as a client goes, the end videos I get usually are declared as 10 fps, although frames can be rather displaced/jittered (which then requires the cutting in video editors). Note that the vncrec-twibright/README states: "The sample rate of the movie is 10 by default or overriden by VNCREC_MOVIE_FRAMERATE environment variable, or 10 if not specified."; however, the manpage also states "VNCREC_MOVIE_FRAMERATE - Specifies frame rate of the output movie. Has an effect only in -movie mode. Defaults to 10. Try 24 when your transcoder vomits from 10.". And if one looks into "vncrec/sockets.c" source, one can see:
void print_movie_frames_up_to_time(struct timeval tv)
{
static double framerate;
....
memcpy(out, bufoutptr, buffered);
if (appData.record)
{
writeLogHeader (); /* Writes the timestamp */
fwrite (bufoutptr, 1, buffered, vncLog);
}
... which shows that some timestamps are written - but whether those timestamps originate from the "original" 'target' PC, or the 'recorder' one, I cannot tell.
EDIT: thanks to the answer by #kanaka, I checked through vncrec/sockets.c again, and can see that it is the writeLogHeader function itself calling gettimeofday; so the timestamps it writes are local - that is, they originate from the 'recorder' PC (and hence, these timestamps do not accurately describe when the frames originated on the 'target' PC).
In any case, it still seems to me, that the server sends - and vncrec as client receives - whenever; and it is only in the process of encoding a video file from the raw capture afterwards, that some form of a frame rate is set/interpolated.
I'd also like to state that on my 'target' laptop, the wired network connection is broken; so the wireless is my only option to get access to the router and the local network - at far lower speed than the 100MB/s that the router could handle from wired connections. However, if the jitter in captured frames is caused by wrong timestamps due to load on the 'target' PC, I don't think good network bandwidth will help too much.
Finally, as far as VNC goes, there could be other alternatives to try - such as VNCast server (promising, but requires some time to build from source, and is in "early experimental version"); or MultiVNC (although, it just seems like a client/viewer, without options for recording).
ffmpeg with x11grab
Haven't played with this much, but, I've tried it in connection with netcat; this:
# 'target'
ffmpeg -f x11grab -b 8000k -r 30 -s 800x600 -i :0.0 -f rawvideo - | nc 192.168.1.100 5678
# 'recorder'
nc -l 0.0.0.0 5678 > raw.video #
... does capture a file, but ffplay cannot read the captured file properly; while:
# 'target'
ffmpeg -f x11grab -b 500k -r 30 -s 800x600 -i :0.0 -f yuv4mpegpipe -pix_fmt yuv444p - | nc 192.168.1.100 5678
# 'recorder'
nc -l 0.0.0.0 5678 | ffmpeg -i - /path/to/samplimg%03d.png
does produce .png images - but with compression artifacts (result of the compression involved with yuv4mpegpipe, I guess).
Thus, I'm not liking ffmpeg+x11grab too much currently - but maybe I simply don't know how to set it up for my needs.
*( graphics card -> DMA -> network )
I am, admittedly, not sure something like this exists - in fact, I would wager it doesn't :) And I'm no expert here, but I speculate:
if DMA memory transfer can be initiated from the graphics card (or its buffer that keeps the current desktop bitmap) as source, and the network adapter as destination - then in principle, it should be possible to obtain an uncompressed desktop capture with a correct (and decent) framerate. The point in using DMA transfer would be, of course, to relieve the processor from the task of copying the desktop image to the network interface (and thus, reduce the influence the capturing software can have on the processes running on the 'target' PC - especially those dealing with RAM or hard-disk).
A suggestion like this, of course, assumes that: there are massive ammounts of network bandwidth (for 800x600, 30 fps at least 800*600*3*30 = 43200000 bps = 42 MiB/s, which should be OK for local 100 MB/s networks); plenty of hard disk on the other PC that does the 'recording' - and finally, software that can afterwards read that raw data, and generate image sequences or videos based on it :)
The bandwidth and hard disk demands I could live with - as long as there is guarantee both for a stable framerate and uncompressed data; which is why I'd love to hear if something like this already exists.
-- -- -- -- --
Well, I guess that was it - as brief as I could put it :) Any suggestions for tools - or process(es), that can result with a desktop capture
in uncompressed format (ultimately convertible to uncompressed/lossless PNG image sequence), and
with a "correctly timecoded", stable framerate
..., that will ultimately lend itself to 'easy', single command-line processing for generating 'picture-in-picture' overlay videos - will be greatly appreciated!
Thanks in advance for any comments,
Cheers!
References
Experiences Producing a Screencast on Linux for CryptoTE - idlebox.net
The VideoLAN Forums • View topic - VNC Client input support (like screen://)
VNCServer throttles user inpt for slow client - Kyprianou, Mark - com.realvnc.vnc-list - MarkMail
Linux FAQ - X Windows: How do I Display and Control a Remote Desktop using VNC
How much bandwidth does VNC require? RealVNC - Frequently asked questions
x11vnc: a VNC server for real X displays
HowtoRecordVNC (an X11 session) - Debian Wiki
Alternative To gtk-RecordMyDesktop in Ubuntu
(Ffmpeg-user) How do I use pipes in ffmpeg
(ffmpeg-devel) (PATCH) Fix segfault in x11grab when drawing Cursor on Xservers that don't support the XFixes extension
You should get a badge for such a long well though out question. ;-)
In answer to your primary question, VNC uses the RFB protocol which is a remote frame buffer protocol (thus the acronym) not a streaming video protocol. The VNC client sends a FrameBufferUpdateRequest message to the server which contains a viewport region that the client is interested in and an incremental flag. If the incremental flag is not set then the server will respond with a FrameBufferUpdate message that contains the content of the region requested. If the incremental flag is set then the server may respond with a FrameBufferUpdate message that contains whatever parts of the region requested that have changed since the last time the client was sent that region.
The definition of how requests and updates interact is not crisply defined. The server won't necessarily respond to every request with an update if nothing has changed. If the server has multiple requests queued from the client it is also allowed to send a single update in response. In addition, the client really needs to be able to respond to an asynchronous update message from the server (not in response to a request) otherwise the client will fall out of sync (because RFB is not a framed protocol).
Often clients are simply implemented to send incremental update requests for the entire frame buffer viewport at a periodic interval and handle any server update messages as they arrive (i.e. no attempt is made to tie requests and updates together).
Here is a description of FrameBufferUpdateRequest messages.
Is it possible to turn on/off power supplies from USB manually with Linux?
There's this external USB cooling fan (the kind you use to cool yourself off, not the PC), and it would be nice to be able to control it from the terminal, because I want to position the fan somewhere far away.
I suppose this could also be useful for a variety of other things as well, because there's a lot of USB toys out there. Maybe air purifiers, etc. (I heard they don't really work though).
According to the docs, there were several changes to the USB power management from kernels 2.6.32, which seem to settle in 2.6.38. Now you'll need to wait for the device to become idle, which is governed by the particular device driver. The driver needs to support it, otherwise the device will never reach this state. Unluckily, now the user has no chance to force this. However, if you're lucky and your device can become idle, then to turn this off you need to:
echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend"
echo "auto" > "/sys/bus/usb/devices/usbX/power/level"
or, for kernels around 2.6.38 and above:
echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend_delay_ms"
echo "auto" > "/sys/bus/usb/devices/usbX/power/control"
This literally means, go suspend at the moment the device becomes idle.
So unless your fan is something "intelligent" that can be seen as a device and controlled by a driver, you probably won't have much luck on current kernels.
Note. The information in this answer is relevant for the older kernels (up to 2.6.32). See tlwhitec's answer for the information on the newer kernels.
# disable external wake-up; do this only once
echo disabled > /sys/bus/usb/devices/usb1/power/wakeup
echo on > /sys/bus/usb/devices/usb1/power/level # turn on
echo suspend > /sys/bus/usb/devices/usb1/power/level # turn off
(You may need to change usb1 to usb n)
Source: Documentation/usb/power-management.txt.gz
PowerTOP from Intel allows you to toggle devices such as usb peripherals in real-time. These are called 'tunables'.
sudo apt install powertop
sudo powertop
Tab over to 'tunables'.
Scroll down to your device.
Hit enter to toggle power saving mode (Good/Bad)
Note that Bad means the device is always on. Toggling to Good will turn off the device after the preset inactive saving time (default is 2000ms).
See the PowerTOP docs for details on how to make these changes permanent.It generates the config scripts for you (pretty much as described by other posters on this thread).
NOTE: These scripts do not affect USB pin power (which is always on).
These only send the driver protocol to activate and deactivate a device.
If you want to control pin power, you could use either a supported smart USB hub, or better yet a microcontroller.
I have found these solutions that at least work for properly configured Terminus FE 1.1 USB hub chip:
1.To turn off power on all USB ports of a hub, you may unbind the hub from kernel using:
echo "1-4.4.4" > /sys/bus/usb/drivers/usb/unbind
to turn power back on - you may bind it back using
echo "1-4.4.4" > /sys/bus/usb/drivers/usb/bind
2.Switching power at each port individually is trickier: I was able to use hubpower to control each port - but it comes with a downside: hubpower first disconnects the usbdevfs wich causes all of the USB devices to disconect from system, at least on ubuntu:
usb_ioctl.ioctl_code = USBDEVFS_DISCONNECT;
rc = ioctl(fd, USBDEVFS_IOCTL, &usb_ioctl);
With this ioctl disabled I was able to switch off individual port power without detaching all devices - but the power goes back on immediately (probably due to kernel seeing an uninitialized device) which causes USB device just to do a "cold restart" which is what I generally wanted to do. My patched hubpower is here
You could use my tool uhubctl to control USB power per port for compatible USB hubs.
I wanted to do this, and with my USB hardware I couldn't. I wrote a hacky way how to do it here:
http://pintant.cat/2012/05/12/power-off-usb-device/ .
In a short way: I used a USB relay to open/close the VCC of another USB cable...
echo '2-1' |sudo tee /sys/bus/usb/drivers/usb/unbind
works for ubuntu
The reason why folks post questions such as this is due to the dreaded- indeed "EVIL"- USB Auto-Suspend "feature".
Auto suspend winds-down the power to an "idle" USB device and unless the device's driver supports this feature correctly, the device can become uncontactable. So powering a USB port on/off is a symptom of the problem, not the problem in itself.
I'll show you how to GLOBALLY disable auto-suspend, negating the need to manually toggle the USB ports on & off:
Short Answer:
You do NOT need to edit "autosuspend_delay_ms" individually: USB autosuspend can be disabled globally and PERSISTENTLY using the following commands:
sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT="/&usbcore.autosuspend=-1 /' /etc/default/grub
update-grub
systemctl reboot
An Ubuntu 18.04 screen-grab follows at the end of the "Long Answer" illustrating how my results were achieved.
Long Answer:
It's true that the USB Power Management Kernel Documentation states autosuspend is to be deprecated and in in its' place "autosuspend_delay_ms" used to disable USB autosuspend:
"In 2.6.38 the "autosuspend" file will be deprecated
and replaced by the "autosuspend_delay_ms" file."
HOWEVER my testing reveals that setting usbcore.autosuspend=-1 in /etc/default/grub as below can be used as a GLOBAL toggle for USB autosuspend functionality- you do NOT need to edit individual "autosuspend_delay_ms" files.
The same document linked above states a value of "0" is ENABLED and a negative value is DISABLED:
power/autosuspend_delay_ms
<snip> 0 means to autosuspend
as soon as the device becomes idle, and negative
values mean never to autosuspend. You can write a
number to the file to change the autosuspend
idle-delay time.
In the annotated Ubuntu 18.04 screen-grab below illustrating how my results were achieved (and reproducible), please remark the default is "0" (enabled) in autosuspend_delay_ms.
Then note that after ONLY setting usbcore.autosuspend=-1 in Grub, these values are now negative (disabled) after reboot. This will save me the bother of editing individual values and can now script disabling USB autosuspend.
Hope this makes disabling USB autosuspend a little easier and more scriptable-
I had a problem when connecting my android phone, I couldn't charge my phone because the power switch on and then off ...
PowerTop let me find this setting and was useful to fix the issue ( auto value was causing issue):
echo 'on' | sudo tee /sys/bus/usb/devices/1-1/power/control
USB 5v power is always on (even when the computer is turned off, on some computers and on some ports.) You will probably need to program an Arduino with some sort of switch, and control it via Serial library from USB plugged in to the computer.
In other words, a combination of this switch tutorial and this tutorial on communicating via Serial libary to Arduino plugged in via USB.
So far I came to the conclusion that you cannot control the power of a USB port. The 5V USB is always provided, and it's up to the device to use it or not. You can check this with a 5V fan or light.
I've tried various methods (disconnect/reconnect/bind/unbind/reset signal). Best so far are bind/unbind as it forces a cold restart of the device (but no power cycle).
I came up with a solution to reset USB devices, ports and controllers in a python script, which supports all of the above methods.
You can find the script at my Github page
Usage:
usb_reset.py -d 8086:1001 --reset-hub
The script uses among others the following solution to reset USB hubs/controllers:
Unbindind a USB port / controller works best via:
echo "myhub" > "/sys/bus/usb/drivers/usb/unbind"
echo "myhub" > "/sys/bus/usb/drivers/usb/bind"
Where myhub is found in /sys/bus/usb/devices/*
Or litteral controllers:
echo "mycontroller" > "/sys/bus/pci/drivers/unbind"
echo "mycontroller" > "/sys/bus/pci/drivers/bind"
Where mycontroller is found in /sys/bus/pci/drivers/[uoex]hci_hcd/*:*