I'm very new to Linux and Bluetooth development, and I'm unsure of the difference between sudo hcitool lecc <bdaddr> and sudo gatttool -b <dbaddr> -I? I don't require any of the GATT services; I just want a connection between the two devices.
I'm looking at vaguely following this widely referred to tutorial, and am looking at adapting the cmd_lecc method in Bluez /tools/hcitool.c, but I am unable to connect to my BLE device using hcitool lecc.
When I connect using gatttool, I am able to connect successfully, however using hcitool lecc returns the error 'Could not create connection: Connection timed out', and no connection is made to the BLE device. However, running sudo hcitool con to show active connections shows that there is one: 'Unknown handle 0 state 2 lm SLAVE'. If it's failing to make the connection, why is it then registering the connection as active in hcitool?
My question therefore is threefold:
What is the difference between the two commands?
Would gatttool be suitable for my purpose, or should I work out what's not working with hcitool (following something like this?
Why does sudo hcitool lecc <bdaddr> partially connect, even when it times out?
Many thanks.
hcitool lecc <bdaddr> creates a connection and returns a handle, while gatttool -b <bdaddr> -I only opens an interactive terminal with an interface bound to the address but not yet connected. To connect using the gatttool command you must then enter connect, which will most likely also fail.
I would suggest looking at how hcitool connects for writing your own code as all of gatttool simply is a wrapper around the same process that hcitool uses, but its wrapper is not available unless you copy its code.
lastly, the handle 0 that hcitool is reporting is an invalid handle left from trying to connect, because as far as I've seen all valid handles are greater than 0.
Related
I have an instance of couchdb running on my local port 5984.
My ultimate goal is to run couchdb on a server within a closed network, and be able to send requests to this server from mobile devices within the network.
This post seems to provide a solution, provided I can open a terminal and make an ssh tunnel:
ssh -f -L localhost:15984:127.0.0.1:5984 user#remote_host -N
But I obviously won't be able to access the command line on mobile devices to make the tunnel. How does one go about accessing applications from mobile devices within closed networks? (I can't just deploy it to some web server as I don't have access to the internet)
You CAN run command line on Android, for example with this terminal emulator you can copy a statically linked ssh binary to /data/data/jackpal.androidterm/app_HOME then cd $HOME and ./ssh to execute it
and there are graphical ssh clients, some of which might have the functionality
also termux should have an ssh client available, you probably need to "apt install ssh" when in the app to get it.
You can create a SSH tunnel if the client supports port forwarding. Those I know are :
The paid version of JuiceSSH : Setting up a New Port Forward Profile
Connectbot : Long press in the hosts list and choose "Edit port forwards". The parameters are straightforwardly adapted from the -L option.
You can write a client via sudo apt-cache search libssh; it supports tunneling AKA forwarding.
#include <libssh/libssh.h>
http://api.libssh.org/master/libssh_tutor_forwarding.html
I'm working on a project where I need to establish connection between my computer and a Adafruit feather 32u4 with BLE incorporated.
Due to comments on lots of webs, I decided to use linux to do the job.
I got everything installed and I can connect my BLE with the PC successfully.
----MY CONNECTION PROCEDURE-----
I can even recieve data and send data between them with gatttool.
To connect both devices i use this commands:
sudo hcitool lescan
sudo gatttool -t random -b F6:E5:F4:A7:71:E6 -I
connect
The devices are connected correctly. I can use all the gatttool commands and they respond as expected.
----END OF CONNECTION PROCEDURE----
---MAIN PROBLEM---
I don't know how I could implement all the commands in a packed C program.
I need to be able to manage all the commands in the same program !! without using brute force with system().
It would be great if someone could show me how gatttool do its magic.
I mainly need to know how to get the data from Rx and how to send it to Tx via code not commands.
Note: I can supply any further information if needed.
My Raspberry Pi 3 can connect briefly to my Android mobile, but once I accept the connection on the Raspberry Pi, I get this error:
GDBus.Error:org.bluez.Error.Failed: No such file or directory. Try to connect manually.
Please help me on this.
You can fix that from Bluetooth control. Type $bluetoothctl as root then you will end up with Bluetooth shall. There you should type "power on" command. After that you can use "scan on" command to check connection.
to continue from Dinusha's answer, after you scan and find your device's ID (you should also be able to see it's name in parentheses) you'll need to pair with the device by doing
pair <device ID>
then connect with the device by doing
connect <device ID>
You'll be able to see status of the connection
There are cases where I use a separate bluetooth dongle for connections I don't want dropped
Raspbian Jessie has some issues as far as I know with the Bluetooth module. I'd recommend using bullseye or buster. Also, there are a couple issues regarding the newest kernel. Run the following command to see if your phone which you are willing to connect is listed:
sudo bluetoothctl devices
If your mobile device is still listed here and not paired on the mobile side, there is your problem. Remove the device using the following command in RPI:
sudo bluetoothctl remove <mac-adress-of-device>
I have an embedded system that is programed in C. I need to do the equivalent to the DOS command Telnet. The idea is to test if the remote host is up and running.
I would like to have some orientation here like:
Open source project that I can use as a guide line (C language)
Some documentation on what the Telnet command does (so I can
implement my own)
Thanks
Update: Thank you for your valuable comments
My system connects to a host via GPRS/Ethernet/dial up/Wifi (one of them). As a developer I check if the host is ok by using my windows laptop (with a Dial up modem, GPRS modem or whatever is needed) and running Telnet like this:
telnet 192.168.0.1 8000
(non real values)
If the host is ok I got the clean screen, otherwise I got an error. That's what I need to do in code, to be able to determine if the host is up and running by using a sort of DOS telnet client command in C.
This is done once, just to check communications, after this test is cleared the real info should be sent.
I'm trying to learn how to write C code that will read from the serial port in Linux. I've found what seems to be a good tutorial here.
I want to be able to test this code, so I think I need either a serial port, or a way to write to the serial port while the code from above is reading.
I'm running Ubuntu 10.04 as a virtual machine on my Mac using virtualbox. My idea was to set up a virtual serial connection and write from the host to the guest. Hopefully something as simple as cat "Hello World" > /tmp/fake_serial in a host terminal, and for that to be read by the program in the link above.
Is this possible? I've tried adding a serial port using virtual box and when I try to do the above command I get an error saying I can't write to a socket.
The second option I thought of was using something like minicom inside the guest OS, to connect to say /dev/ttyS1 and write messages for my code to read at the same time. Again, assuming that the baud rates and other settings are OK, would this be possible?
I don't have a lot of experience working with serial ports, so I'd appreciate any suggestions about the best way to do this. Thanks in advance.
So to get this working I just added another Ubuntu VM on VirtualBox, and connected the two together via a virtual serial port. My main, original VM, which I use for a lot of developing will be referred to as VM1. The new VM, with a small hardrive that will only be used for sending messages to VM1 will be called VM2. These are both Ubuntu 10.04 VMs.
In VirtualBox go to Settings for VM1, go to ports, and change the settings as follows:
Now go to VM2, and select settings, ports, then change as follows:
Now first you need to start VM1. When that's booted then boot VM2. Now you can open a terminal in VM1, and type screen /dev/ttyS0 38400 (you may need to run sudo apt-get install screen before this works). Then go to VM2, open a terminal, and type echo "Hello" > /dev/ttyS0.
You should see Hello appear in the terminal open in VM1. When you're done running screen press ctrl-a k to kill it, otherwise if you try to do other stuff with the serial port you may get an error message saying that the port is busy.
When I had to do some serial port testing from my real to virtual machine I ended up doing a "loop back" type testing. I took two USB-Serial converters and a RS232 F-F adaptor and connected my machine to itself. Then in VirtualBox under Settings->USB you can route one of the two USB-Serial converters to be "owned" by your VirtualBox.
Once you plug in the converters one will register with the Mac and one with the Ubuntu "computer" then you can do serial communication as normal between the two machines.
You may also be able to emulate a virtual serial port using a pty ("pseudo-teletype" device), but I'm not positive on that one since I believe the ability to do that was locked down in newer kernels.
I ran into a similar situation running a QNX guest using VirtualBox 5.0.10 on an Ubuntu 14.04 host.
My solution seems general enough to apply to the above-mentioned case.
I configured the guest VM in the same way that Kells1986 setup his VM1:
Under the "Serial Ports"/"Port1" tab:
check "Enable Serial Port"
set "Port Number" to "COM1"
set "IRQ" to "4"
set "I/O Port" to "0x3F8"
set "Port Mode" to "Host Pipe"
uncheck "Connect to existing pipe/socket"
set "Path/Address" to an accessible file-system path (e.g. "/home/safayet/vmSerialPipe")
According to the VirtualBox manual:
You can tell VirtualBox to connect the virtual serial port to a
software pipe on the host. ... On a Mac, Linux or Solaris host, a local domain socket is used ... On Linux there are various tools which can connect to a local domain socket or create one in server mode. The most flexible tool is socat and is available as part of many distributions.
A domain socket is an IPC mechanism on UNIX systems similar to a pipe.
I connected to the "pipe" end of the virtual serial port on the Ubuntu host using the socat command:
socat - UNIX-CONNECT:/home/safayet/vmSerialPipe