I have some old serial based USB touchscreen systems that would be expensive to replace with new hardware.
They are connected in the following manner:
Serial Mouse -> Serial to USB adapter -> Thin Client -> Virtual Machine
Everything works great with one issue. I'm experiencing a driver crash everything user either logs off, shutdown, or reboots. The current workaround has been to disable the serial mouse device before logging off which is a real pain. As long as the device is disabled, everything works great.
I did a lot of research on this issue by taking memory dumps of the crash virtual machines.
It seems like when the user logs off, the USB device is abruptly disconnected and then Windows tries to disable the device gracefully and waits until it is confirmed, thus hanging forever. In assembly it appears to call a .sys file that never returns back.
Is there anything that can be done with an issue like that? Can you change the device shutdown order? Or perhaps tell Windows to not ensure the plug and play device is shutdown? I doubt the vendor would be willing to change their driver.
I wrote a custom solution to this problem.
The application uses the ShutdownBlockReasonCreate API call to block Windows from shutting down. It then listens for reboots or logoffs using the WM_QUERYENDSESSION API call. When it gets this, it disabled the devices and then destroys the shutdown block created.
A real pain but it works
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So, I programmed an ATMEGA32u4 and when I connect the device, it doesn't run the code. Instead, it gets recognised as an ATMEGA32u4 chip in Windows device manager.
To get the code running I have to open Atmel FLIP and open USB and then have to press the start application button after which it gets recognised as a HID in device manager and works as intended. I don't know why and what is happening.
The reset is pulled high with a 10k and the HWB is pulled down with a 10k and the chip has the factory bootloader on it.(if this helps)
Pulling down HWB is what you do if you want to start the bootloader built into the ATmega32U4. It sounds like you want to run your own code instead of running the bootloader so you should pull HWB up, or disable the HWBE fuse.
When a new device pluged in to, let's say, a USB hub. What is the magic work behind the scene between
a device is pluged in
the user of the computer can use the device
After several days of digging. There is still some confusions that I can't worked out on my own.
Currently my understanding of this processing is that ( in windows system ):
A device pluged in
Windows look up in its registry to find a appropriate driver for it
call the DriverEntry routine of the driver
call the AddDevice routine of the driver
What role of a Plug and Play Manager is playing ? It seems like this processing can work fine even without one.
I need to use a monitor as a "private" device for my special application, I want to use it as a flashlight of a sort and draw special patterns on it in full screen. I don't want this monitor to be recognized by OS (Windows 7) as a usual monitor. I.e. user should not be able to move mouse to that monitor, or change its resolution, or run screensaver on it or whatever. But I want to be able to interact with it from my application. Monitor is plugged using an HDMI cable to a video card (most probably nVidia).
What is the simplest way to do this? All solutions are appreciated, including purchasing additional adapters or simple video cards, or any other special devices. The only solution I could imagine for now is to plug the monitor to another computer, run a daemon on that computer, connect it to my computer via ethernet or whatever, communicate with that daemon from my computer. It is pretty ugly and require additional computer. But I need to solve this problem.
To do this, detach the monitor from the desktop. Detaching a monitor from the desktop prevents Windows from using it for normal UI.
Sample code for attaching and detaching monitors is in this KB article. Once you've done that, you can use the monitor as an independent display.
Building upon your own idea of using an external PC, and Mark's comment on using a VM as this "external" device:
You could buy an external USB-to-VGA video adapter like one of these, approx. USD40:
http://www.newegg.com/USB-Display-Adapters/SubCategory/ID-3046
Almost every VM software supports some kind of USB passthrough. VirtualBox is a great example.
Only the VM sees the USB device, the host ignores it completely.
So the steps would be:
Buy said USB-to-VGA adapter.
Configure slim a virtual machine and cook up a little utility to receive the images to show on he screen by network.
Configure VirtualBox to connect the USB-to-VGA adapter directly to the virtual machine.
Here is another simple solution to monitor you application.
Your app should provide an API monitor service, served as HTTP on any port you want (for example http://{userip}:{port}/{appname}/monitor).
Your app monitors itself, keeping monitoring data in memory, in a local file or a database, hidden from the user. The monitor API serves this data to any device you want that has a browser (tablet, phone, netbook, android mini-PC, low cost linux device, any PC or any OS... from the internet, your LAN or direct connection to the PC hosting the app).
Pros:
Data to monitor is collected (and served) within your app : only one executable
Display can be done remotely : from anywhere !
Access security easily done using standard HTTP authentication mecanisms
You can monitor several applications (ie several monitoring URLs)
You are free to use any browser to monitor (even a local window browser on the same PC for testing purposes)
Monitor from any hardware and OS you want
Simple and flexible !
Cons:
There is few, but tell me...
Choosing this solution depends on what kind of data you need to monitor (text, images, video...), and also on what is the refresh rate you expect depending on your system network configuration.
Hope it helps :)
I need to set up USB communication between a Windows 7 host and a Linux device for data transfer. I was able to compile the Linux kernel on the device to include the Gadget Zero driver in the kernel (not as a loadable module - Linux version 3.0.15). My project has some requirements, which also explains why I chose Gadget Zero:
1) On the Windows 7 host, a kernel mode driver must be used to communicate over the USB connection for sending and receiving bulk data. (speed is not important, not a lot of data at once).
2) On the linux device, no requirements on USB side except send and receive data easily over USB link. The data received will eventually be "unmarshalled" to call functions in another kernel module (and those responses packaged and sent back to the host).
3) Multiple linux devices will be connected to the host, so need easy way to enumerate connected devices and communicate with them.
So due to the requirements, I decided against the Gadget Serial. I'm having serious issues sending and receiving data over the virtual COM port in kernel mode (KMDF) in Win 7 host. WinUSB does not seem to want to open my attached device (I'm using KMDF windows USB driver from template in VS2012) Also, the gadget serial driver on the linux side, I cannot find the functions where the data is received and sent. Plus, any received data on the linux device seems to be echoed back to the host for some reason. (and to test this, I wrote a simple user-mode app in Windows, which is a no-no for my project).
Gadget Zero, it appears much simpler on the linux side. I can plug the USB cable to the Win7 host, and I can get the device to appear in the device manager. However, again I am having problems with getting communication going over the link. Gadget Zero has 2 bulk endpoints, so this shouldn't be an issue. Surely, someone has made data communication possible between a Windows host and a linux device using Gadget Zero? With Gadget Zero, it should be easy to enumerate the connected linux devices and communicate with them.
The trick is to keep the Windows side communication in kernel mode. Can someone point me in the right direction perhaps with Gadget Zero, Windows 7 KMDF, and some sample source code? I have a hard time believing no one has done this before because my internet searches don't turn up much. (and mostly user-mode solutions with Gadget Serial).
Thanks!
So you're writing a Win32 driver in which you want to communicate with your linuxed usb? I haven't written much win32 kernel code, but I believe I've seen a huge section in the doc, saying something like "This is how you make usb drivers"... That'd be it. In other words, when in kernel mode you have access to the full kernel usb layer. You don't need an existing driver or whatnot.
On the linux side you can use the serial gadget, in a different run mode. Only the default run mode, registers it self as VCP. There exist a more basic mode:
modprobe g_serial use_acm=0
Give it your own vendor id and you'll be able to attach your very own custom win32 driver. The 'multiple linux devices' will be handled by Windows. (Multiple instances of your driver, will be initiated.)
The echo you're seeing btw, is most likely a terminal feature. (The terminal mode on uarts will echo.) You have to disable it, when connecting. And now that you're at it, you also have to disable the xon/xoff, esc chars etc. (Standard legacy rubbish.)
And another thing. I'm not sure the gadget zero actually sends the data onto the line. It's meant for testing the gadget framework. (I could be mistaken though.)
Anyway, you've prolly solved this issue years ago. I'd be nice to know what you came up with.
Whenever I disconnect my Windows Phone from PC (connected through USB) and if my application is running, my application hangs for sometime and then application crashes.
Does anyone experienced same behavior? I guess switching for PC connection to Wi-Fi/GPRS is causing the issue.
the windows Phone Requires that you Safely Remove hardware first, after a few times when i started Development on the windows phone i did the same and Ended up getting a new Phone. So plainly put, try to Safely Remove and Make sure it is installing the app to the Device.
Meaning if you Remove the phone, the App is still able to be ran just like a normal downloaded App form the Market place.
if you want more in depth information, i would suggest Reading the WP7 Everything Programming ebook lol
its filled with good information, and Definitely Helped me along my road to Love DEV for WP7.
As gamernb says, if you disconnect the USB from a properly tethered Windows Phone (i.e. connected to Zune, or using the WPConnect utility), the phone's network connection will be reset and your app's connections will be terminated. The phone will then start trying to connect using WiFi or cellular data (if they are on), but this can take quite a while.
You will have to handle this network disconnection in your app - I've found that pulling the USB cable in this way is a good ad-hoc test for WP7 apps: do an action which you know will use the network connection. Then watch if the app crashes, or handles this gracefully.
Actually you aren't guaranteed to always use the PC data connection: if you make sure that the computer has no data connection (i.e. pull the Ethernet cable, turn off WiFi etc ), the WP7 app can then use cellular data or WiFi on the phone instead.
Alas-
you could set perimeters in your application to Check what the connection type is, then Make changes accordingly.
You May have a slight freeze, but that's better then a crash....mainly when the phone switches from PC to WWAN, their would be a slight Pause.
use the Reachability Class and NSLog to Figure out whats going on exactly.
I really hope that helps!