I was able to make a working HID USB stack on my "StartUSB for PIC" board for the 18F2550 microcontroller. I based it on one of the MLA libraries, which was made for the 18F45K50 (MLA 2018_11_26, hid_custom, picdem_fs_usb_k50.x), but I converted it to work with the 18F2550 (there might have been easier ways, but only learned to work with PIC about 1 month ago). On the host side, I'm using LibUsbDotNet (also here, there might be easier ways - the documentation on this library really sucks) on a Windows 10 machine.
I'm using the HID class, full speed, and all seems to work. Although, I get some random errors on the host PC (see below), but doing one close/re-open cycle on the host side when getting the error is kind of solving it. Dirty, but it works. So I kind of ignore this now.
Win32Error:Win32Error:GetOverlappedResult Ep 0x01
995:The I/O operation has been aborted because of either a thread exit or an application request.
I'm not an expert on USB (yet). But all examples I'm seeing are based on 1) you send first a command to the device and 2) then you retrieve the answer from the device. I did some performance tests, and see that this indeed shows that I can do about 500 cycles/second. I think that is correct, because each cycle, sending command and retrieving answer, each takes 1 msec.
But do I really need to send a command? Can't I just keep reading endlessly, and when the device has somthing to say, it does send the data in an IN transaction, and when not it ignores which creates a timeout on the host side. That would mean that I can poll at 1000 cycles/second? Unfortunately, I have tried it by changing my implementation on the PIC, but I get very weird results. I think I have issues with suspend mode. That brings me to another question - how can I make the device get out of suspend mode (means that not the host, but the device should be triggering this event). I have searched the MLA library for command such as "wakeup", "resume", ... but couldn't find anything.
So, to summarize, 2 questions:
Conceptual: Can I send data from device to host without being requested for it by a command from the host?
For PIC experts: How can I have a device trigger for a wakeup from suspend mode?
And indeed, the answer is Yes on the first question.
In the meantime, I found another link on the web that contains a Visual Studio C# implementation of a USB library including all the source files.
If you're interested, this is the link
This C# host implementation works as a charm. Without sending a command to the device, I get notified immediately if a button is pressed. Great!
It also proofs that my earlier device implementation based on the original MicroChip MLA, is 100% correct. I stress tested the implementation by sending a "toggle LED command" as fast as I could, and I reach 1000 commands/second. Again great!
I think that LibUsbDotNet isn't that perfect after all. As I wrote above, I get rather unstable communication (Win32Error). But with this implementation, I don't get a single error, even after running for half an hour # 1000 commands/second.
So for me, case closed.
Related
I am using the UI Automation COM-to-.NET Adapter to read the contents of the target Google Chrome browser that plays a FLASH content on Windows 7. It works.
I succeeded to get the content and elements. Everything works fine for some time but after few hours the elements become inaccessible.
The (AutomationElement).FindAll() returns 0 children.
Is there any internal undocumented Timeout used by UIAutomation ?
According to this IUIAutomation2 interface
There are 2 timeouts but they are not accessible from IUIAutomation interface.
IUIAutomation2 is supported only on Windows 8 (desktop apps only).
So I believe there is some timeout.
I made a workaround that restarts the searching and monitoring of elements from the beginning of the desktop tree but the elements are still not available.
After some time (not sure how much) the elements are available again.
My requirements are to read the values all the time as fast as possible but this behavior makes a damage to the whole architecture.
I read somewhere that there is some timeout of 3 minutes but not sure.
if there is a timeout, is it possible to change it ?
Is it possible to restart something or release/dispose something ?
I can't find anything on MSDN.
Does anybody have any idea what is happening and how to resolve ?
Thanks for this nicely put question. I have a similar issue with a much different setup. I'm on Win7, using UIAutomationCore.dll directly from C# to test our application-under-development. After running my sequence of actions & event subscriptions and all the other things, I intermittently observe that the UIA interface stops working (about 8-10min in my case, but I'm heavily using the UIA interface).
Many different things including dispatching the COM interface, sleeping at different places failed. The funny revelation was I managed to use the AccEvent.exe (part of SDK like inspect.exe) during the test and saw that events also stopped flowing to AccEvent, too. So it wasn't my client's interface that stopped, but it was rather the COM-server (or whatever the UIAutomationCore does) that stopped responding.
As a solution (that seems to work most of the time - or improve the situation a lot), I decided I should give the application-under-test some breathing point, since using the UIA puts additional load on it. This could be a smartly-put sleep points in your client, but instead of sleeping a set time, I'm monitoring the processor load of the application and waiting until it settles down.
One of the intermittent errors I receive when the problem manifests itself is "... was unable to call any of the subscribers..", and my search resulted in an msdn page saying they have improved things on CUIAutomation8 interface, but as this is Windows8 specific, I didn't have the chance to try that yet.
I should also add that I also reduced the number of calls to UIA by incorporating more ui caching (FindAllBuildCache), as the less the frequency of back-and-forth the better it is for the uia. Thanks to the answer of Guy in another question: UI Automation events stop being received after a while monitoring an application and then restart after some time
I'm writing a simple virtual serial port device to report an older serial port. By this point I'm able to enumerate the device and send/receive characters.
After a varying number of bulk-out transmissions from the host to the device the endpoint appears to give up and stop transferring data. On the PC side I receive a write error, and judging from a USBlyzer trace the music stops on a stall (USBD_STATUS_STALL_PID). However my code never intentionally issues a STALL condition on that endpoint and the status flag for having generated one never gets set though.
Given the short amount of time elapsed (<300 µs) between issuing the request and the STALL it would appear to be an invalid response of some sort, and not a time-out. On the device side the output endpoint is ready to go, with data in the buffer and proper DATA0/1 synchronization, but nothing further ever happens.
Note that the device appears to work fine even for long periods of time until I start sending "large" quantities of data. As near as I can tell the device enumeration/configuration also appears to complete successfully. Oh, and the bulk-in endpoint continues to work just fine after this.
For the record I'm using the standard Windows usbser.sys driver and an XMega128A4U µP. I'm also seeing the same behaviour across multiple Windows Vista and 7 machines.
Any ideas what I'm doing wrong or what further tests I might run to narrow things down?
USBlyzer log,
USB CDC stack,
test project
For the record this eventually turned out to be an oscillator problem. (Apparently the FLL's reference is always 1,024 Hz even when the 1,000 Hz USB frames are chosen. The slight clock error meant that a packet occasionally got rejected if it happened to contain one too many 1-bits in a row.)
I guess the moral of the story is to check the basics before assuming you've got a problem with the higher-level protocol. Also in retrospect a hardware USB analyzer would have been a worthwhile investment, the software alternatives mostly seems to spit out a generic error code or nothing at all when something goes awry.
Stalling the out-endpoint may happen on an overflow of the output buffer on the host side. Are you sure that the device does fetch the data it receives via out-endpoint - and if so does it fetch the data at least as fast as data is sent to the device?
Note that the device appears to work fine even for long periods of
time until I start sending "large" quantities of data.
This seems to be a hint for an overflow of the output-buffer.
I have been working on Reachability class for a while and have tried both the one from Apple sample and the one from ddg. I wonder whether the Reachability class keep sending / receiving data after starting the notifier.
As I'm developing an app which connect to different hosts quite often, I decided to write a singleton and attach the reachability classes I need on it. The reacability classes would be initiated and start their notifiers once the app start. I use the singleton approach as I want this singleton class to be portable and can be applied to other apps without much rewriting. I am not sure if it is good idea to implement like this but it worked quite well.
However, someone reported that the battery of his device drain significantly faster after using the app and someone reported more data usage. My app does not send / receive data on background so I start wondering if it is related to the reachability.
I tried profiling the energy usage with Instrument and I notice that there are continuous small data (few hundred bytes in average) coming in via the network interfaces even I put my app in idle. However, there are almost no data sending out.
I know that Reachability requires data usage when initiate (resolving DNS etc) but I am not sure that whether it still keep using data after starting notifier. Does anyone can tell?
I am not familiar with the low-level programming, it would be nice if someone could explain how does the Reachability work.
I use Reachability, and while I haven't monitored the connections, I have browsed the code, and I can't see any reason why it would keep sending ( or receiving).
If you have a ethernet connection to your Mac, it is quite easy to check. Enable sharing over wifi of your ethernet connection. Install little snitch, it will run in demo mode for three hours after every boot. Turn off the data connection on the test device and connect it to your mac over wifi.
This will allow you to see any network access your test device is making.
If this isn't possible, you can also run your app in the simulator as the network side should be the same, so you should be able to check.
There are also a ton of other tools to track network activity, but I think little snitch is the easiest to use.
I'm new to driver programming in general and also to USB. However, I managed to write a driver for Windows CE (6.0) and I also had access to an USB-Sniffer to read all traffic between the host and the device.
The problem now occurs on some boards (2 out of the 3 I have):
When the device has no data to send and I issue an Interrupt-In-Transfer the device sends an ACK.
So far this is expected. However, something (I guess either the USB-Controller or WinCE) seems to automatically issue more IN-Transfers (3 on one board, 4 on another) and I get subsequent ACK. This isn't a problem so far either.
But the next IN-Transfer will also result in an ACK, no matter if there is data to send or not, I receive zero bytes in the driver.
Yet, when I look at the USB-Sniffer the proper telegram was send, however 2 more IN-Transfers are automatically issued and are responded with an ACK. So it seems like the data is overwritten by the ACK.
I tried everything that came to my mind so far: Reset the pipe, close and reopen the connection, but nothing seems to work out properly. Resetting the Pipe solves the problem in about half of the cases though. I really ran out of ideas for solving the problem.
Is there a way to tell the USB-Controller (or WinCE or whatever causes this behaviour) to always only issue one single transfer?
EDIT
Turns out it was a threading issue. Unfortunately I wasn't the one who fixed it and I have no access to the working solution, thus I cannot give further details.
Over the past two days, I am doing some reading on how to get data over USB from an external device which has no device driver installed. I have to read data from a WT500 Yokogawa Power Meter (basically I want to read just one of the parameter that the meter shows, just the power values) over USB. I am aware that a device driver for WT500 is available, but it has some dependencies and I do not want to install a software or change anything majorly in our node to cater to that.
I have found that libusb could be used to perform what I would want, and I have a C program that sniffs the USB device and returns some information. I have looked into usb-robot as well, which also uses libusb. The server node that I am probing has OpenSUSE Linux kernel 2.6.30. I have usbfs mounted.
Question:
I am expecting that using libusb, I would be able to get data dumps from the power meter whenever I request, via usb device. Can I request the meter something like - send 25k of data, and then upon parsing it, I get the parameter value that I am looking for? Considering that I have zero knowledge about the device, can I get some meaningful values out of it? An example code would help.
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There are some standard messages like ?IDN with which a USBTMC device could be queried. However, specific queries need to be sent to a meter (the syntax should be there in the technical doc/manual/communication interface) if one needs to get whatever is showing up on screen.
I guess there are no easier ways of doing what I want - like just reading a file using something like fread ??
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Yes, almost. If USBTMC module is installed (the default one in our kernel did not work, detailed explanation of installing and querying a device is here - http://code.google.com/p/scte/wiki/USBTMC), then one just needs to send some queries and read the response via cat or something from the specific files under /dev.
From the meter technical document, I see that the driver communication interface that is described is Windows specific, so I reckon I might need to do some reverse engineering.
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Yes, but only a tiny bit or may be not at all.
Thank you.
EDIT: After a bit of googling I think I have the answers, I have added them next to the questions I asked.