What does "connected" mean with Bluetooth devices on Windows?
Observation that prompted this question:
1. I paired a Bluetooth device with my laptop (Windows 8.1).
2. The screen said, "pairing..." then "connected."
3. I was then able to receive data from the device and send it to a program I wrote.
4. I restarted the computer and checked the Bluetooth device list and my device was "paired" (not "connected" like before).
The part that confuses me is that I could start my program up and read data from the devices even though it said "paired" as the status and not "connected." I know that paired is similar to introducing a device to a system (I read about it here). However, given my observation, I don't see what the difference between paired and connected is. It seems like I can transmit data whether I'm connected or just paired.
I figured out what was going on. It has nothing to do with different paired and connected definitions in Windows but with how BT and BLE work. In Windows, when you send data over Bluetooth or Bluetooth Low Energy, the notification that something is being sent establishes the connection between the computer and the device.
I tested this using Bluetooth and BLE and as soon as the device stopped sending data, the status went to "paired." When it started sending data again, it changed to "connected."
Here is a link to the MSDN forums that pointed me in the right direction.
Related
According to the documentation, geofencing uses cellular network and wifi signal for detecting a location, but it seems like it doesn't work without a connected companion device.
Does Android Wear work with geofencing without paired handheld?
Update:
Just had a quick play with this, doesn't seem to work yet when BT disconnected and wifi connected.
Original reply:
Not all wear devices have the hardware to support this, though the LG urbane 2 has LTE and quite a few Wear devices support wifi.
I would think this works considering other services work that use location with wifi/gps.
Can you check these items?
Verify your Wear device supports wifi, i.e., it has a wifi chip
When disconnected, check wifi is enabled under settings (this should happen automatically)
Wait some time (even 5 mins) for a signal
More details:
If your wear device has wifi, it should actually turn on if the Wear device becomes disconnected from the phone via bluetooth. You can verify this by looking in the settings as noted above.
I have noticed with the FusedLocationProviderApi it can sometimes take quite a bit of time to switch to the on-board chip when the phone becomes disconnect, so it may be the case with the Geofencing as well. FYI, Google Play Services always uses the phone's hardware first to save battery. It only uses Wear hardware when the phone disconnects.
I am wondering whether it is possible to display a message to the user when he connects a USB device. For example, I want to program the USB so that any PC that the device is connected to displays the pop-up window, saying Please leave the usb on this place.
It is NOT possible;
You wrote: " I want to program the usb so that any PC that the device is connected "
You'd rather program the PC not the USB
USB is a storage device only. Unfortunatelly you can't program all the PC's that USb might get into
The ONLY way this might be (yes it won't work in every case I guarantee) be tweaked is to have autorun.inf file in the USB pointing to a program on the USB that displays the message you want.
[Autorun]
Open=msg.exe
Due to most modern operating systems have tons of blocking mechanism to stop autorun programs this message has very slight chance to appear
You will need to first register for device notification. Then, you can implement a callback to detect when your USB device is inserted or removed. Within that callback you can do your messaging to the users based of your inspection of which device was inserted or removed.
This is only possible if the computer already has a driver installed for this device that implements this behavior. If, as I suspect, the device is actually a standard USB storage device, this is not possible.
Does anyone out there who has developed on a dev board attached to a Mac OSX machine's USB port know how to send AT tty modem commands to the board? Arduino folks? Anyone?
TL;DR
I purchased a development STEVAL-SPBT2ATV2 "USB Dongle for the Bluetooth class 2 SPBT2532C2.AT module", which, according to the docs and spec has "downloaded FW, enabling the user to create a Bluetooth link with simple AT commands."
Which would be great, except all the documentation is only for old MS Windows, and doesn't give any hints on how to program this device from OSX or Linux.
Do I need to install a driver of some sort? Everything I've tried is like talking to a brick wall: I send commands, but nothing comes back from the board.
Things I've tried:
/dev/tty.Bluetooth-Modem already existed. Didn't seem to do anything. I think that's the built-in bluetooth device.
/dev/tty.AmpedUp-AMP-SPP and /dev/cu.AmpedUp-AMP-SPP showed up when I went to "Network -> set up bluetooth device" - which is good (correct device name) but strange, why under network?
Then under Bluetooth I can add a "serial port used to connect to this computer" and get the choice of Modem or RS-232. I guessed Modem.
I really hope I don't have to mess with the /etc/tty files
Nothing. the device never seems to react, or send any data back. I've tried several ways to send data to the device. Silence.
echo "AT+AB GPIOConfig 2 O^M" > /dev/cu.AmpedUp-AMP-SPP # ctrl-v ctrl-m for the ^M
screen /dev/tty.AmpedUp-AMP-SPP
cat /dev/tty.AmpedUp-AMP-SPP
minicom # via brew
chat /dev/cu.AmpedUp-AMP-SPP
From the docs:
Each dongle has the following factory default:
UART: 115200 baud, no parity,1 stop bit,8 data bits
Local name: “Amp'ed UP!’
Class of device: Misc Device
Profile: SPP (serial port profile)
Service name: “AMP-SPP”
Deep sleep: disabled
Page and inquiry scan: 1.28s interval, 11 ms duration
Security: disabled
Bonding PIN: “1234”
Bonding allowed: always enabled
I figured out where I was wayyy off-base with some help from a friend.
I thought that I was trying to establish a OSX->Terminal->Serial (Over USB)->Chip communication channel to program the chip.
When in reality, I was trying to establish a OSX->Terminal->Serial (over Bluetooth->Bluetooth) -> Chip channel to talk to the chip using the existing firmware, which includes enough defaults to have 4 GPIO/LED outputs. The USB only comes in later if I want to change the firmware.
Which means plugging the board into my laptop's USB port isn't necessary and only complicates the issue - better is plugging it into a spare USB charger next to my laptop.
... Which let me narrow down the problem to 2 things:
OSX isn't holding an open bluetooth communication channel to the BT device, so of course I won't be able to talk to it, even if the serial port is set up right
Even if I could talk to it, Apple iOS is so locked down that I won't be able to connect to it from an iPhone/iPad. :(
Do you know a way to use the Windows XP API to reset the USB bus? In other words, I'd like the OS to kick out any USB devices that are currently connected, and then auto-detect everything anew.
I'm aware of devcon, and I suppose I could do system calls out to it, but I'm hoping for a direct call into the API.
From kernel mode: You can force a specific USB device to be re-connected, as if it was unplugged and replugged again, by sending an IOCTL_INTERNAL_USB_CYCLE_PORT to its PDO. (This can only be done from a kernel mode, e.g. through a helper driver.) This 'cycle' operation will cause a USB reset to occur, after which the device would be re-enumerated. For example, if the device comes back with a different USB device descriptor, a different driver may be matched for it.
From user mode: You can do this by ejecting the device through the CfgMgr API. For example, to go over all USB hubs and eject all devices:
Find all devices having device interface GUID_DEVINTERFACE_USB_HUB with SetupDiGetClassDevs(... DIGCF_DEVICEINTERFACE).
Enumerate over the returned device information set (SetupDiEnumDeviceInfo).
For each device, get the DevInst member:
Invoke CM_Get_Child(DevInst) and then CM_Get_Sibling repeatedly to go over all child nodes of the hub (i.e. the USB devices).
For each child node, call CM_Request_Device_Eject.
Well, use can use the Setup API (SetupDiXXX functions) to enumerate the USB devices in the system, and then call WinUsb_ResetPipe on each one, but I'm not sure if that's what you're looking for. It's been a while since I worked with USB devices, but as I recall, there is no standard way to reset a device (i.e. simulate a power off/power on cycle). If it's possible for a particular device, you'd have to send an appropriate IOCTL (using DeviceIOControl) to the driver. The IOCTL would vary from manufacturer to manufacturer.
It's possible to cycle the parent port on the USB hub the device is attached to, as well. This will result in, among other things, apparrent unplug/replug actions, as you will see a balloon popup when this occurs.
Much of this is poorly documented, and honestly, I've gotten the impression there are only a handful of people at Microsoft who really understand it well. The design decision I've made for future devices I design is that I intend to include watchdog functionality on both sides, as well as a device-side full reset function. That way, if the device figures out it is confused, it can just cut its own power for a second and fully reset, if the host can't communicate with it, it could do the same thing, and if the device thinks everything is fine but the host knows better, the host could order it to reset.
There are at least three APIs worth looking into for this problem: the Setup API, the Config Manager API, and various WMI extensions. However, be cautious about diving into WMI if you intend to use an Embedded XP target, as you will have to include a lot of other things in your OS image you might otherwise not need.
As far as I know, there is no way to do this - you can issue a command to have PnP rescan the bus for new devices, but that isn't the same as issuing a bus reset.
Furthermore, just because from a hardware perspective you issued a bus reset doesn't mean that Windows will remove the PDOs that represent the children of the hub and redetect them; the USB bus driver can (and does) do just what I describe (i.e. issue hardware bus resets without disturbing the device tree), and only after the device doesn't respond does it issue the surprise removal and yank it from the tree.
I'm looking for a very specific USB device for debugging systems that may use USB but not with a regular computer (proprietary hardware). I want a device that has a USB host controller and two USB device connections. The device to be debugged is connected to the USB host controller and one of the device connections is connected to another device with it's own host controller on it. The the other device connection is connected to a pc. The point being that all USB data travelling through the device (from the device connected to the host controller to the device connected to the first device connection) is reported to the pc.
I'll happily write software to do the logging (in fact I want to) but I can't seem to find a board like this anywhere. Can anyone help?
I have an Ellisys USB analyser, which isn't exactly what you describe internally, but does sit between a peripheral and a host and use a separate PC to collect the data.
(i.e. it has two 'B' and one 'A' connectors on it.)
Excellent product, and very helpful company.
Sniffing the USB shouldn't be too hard if you have the right hardware. And that is the tricky question. I haven't seen anything that describes the USB breakout box that you want. However I can say that this is in the realm of the following two magazines:
Nuts and Volts
Circuit Cellar
If they don't have a USB breakout box project in their archives, then at least they will have advertisements for small cheap single board computers that would have multiple USB ports that you can use for buffering the signals and reporting it back to your PC.
Alternatively is it possible to just wire your PC up to the middle of your two devices and write a custom drive that echos data back and forth while sniffing off a stream for you?
Sorry for the long delay in my reply -- I checked out one of our USB developer's toolchain, and he uses a Beagle USB Sniffer. He seems happy with it.
You're looking for a USB device with two upstream outputs. I think according to the USB spec, this is not possible. You will have two USB hosts trying to send messages and control the USB devices at the same time.
What if you were to look for a device which allowed you to view the data going through a hub via something other than a usb output?
If you're building something custom, take a look at this USB chip site. The chips are programmable via a windows application. Once you define how you want it to operate, it's saved on an EPROM on the dev board ($30-$50).
Sorry if this isn't helpful!