Is there a cross platform way to receive a signal (or other notification) in Qt, when a new serial port device becomes present, or one that was present before becomes absent? This is a simple case of getting to know when someone connected a new USB to serial port converter (discovering COM ports in windows and ttyS in linux). My only idea now is to periodically (for example using QTimer) run the QSerialPortInfo routines. Is there a way to accomplish this with event driven system? I would appreciate all help.
As of Qt 5.9, there is no such cross-platform way.
Whatever you'll do will be platform-specific.
Related
I have a Wemos D1 Mini (ESP8266), flashed with WLED and I want to create an application like .exe and have control on turning it on/off and choose colors. Does anyone have any idea how I can do without to connect on wifi and just do everything via USB?
To control the WLED firmware over USB, you would use the firmware's ability to be controlled over a serial connection. It looks like you would open the virtual serial port that appears when you plug in the device, at a speed of 115200, and then you take the same JSON that you would POST to /json/state for controlling it over WiFi, and instead send it over the serial connection, and get your responses back over the serial connection.
You could also implement the TPM2 protocol, or the Adalight protocol (which doesn't really seem to be documented except in code), as those are also supposed to be supported.
If you want to do all this in C++ on Windows, you might start by reading the (very old) Windows tutorials for Win32 API serial port programming. If you only want to target Win10 or newer, you could learn C++/WinRT and then use the new WinRT serial APIs. Or you could consult the answers to this question about serial programming on Windows.
I'm quite new to programming at linux and its file-based communication.
I need to create a virtual modem (or modem emulator) at linux machine. The idea is that the software module that sends commands to hardware modem on an FPGA,
At FPGA:
SoftwareModule <= ttyACM => HardwareModem
What I need to achieve at my computer:
SoftwareModule <=> MyModemEmulator acting like a fake UART
Purpose is that the software module can be tested on a linux machine where I have a fake software modem UART(?) port. So the software module sends the modem commands and my fake modem module catches and responds accordingly. So my module will be actually acting like a hardware modem.
What could be the steps I need to take for that? I'm quite new to working with serial ports and don't have deep knowledge of linux or hardware stuff.
I have come across 'socat' but I'm not sure if that can really serve the purpose.
So far I have only learned how to create a basic file system with FUSE (as it was suggested by someone), but I'm not sure how can I use it for my purpose. I'm not looking for a proprietary solution, and not looking for windows based solution either.
Please guide me to the right directions.
Thank you !
Creating a Fake Serial Port to Emulate Modem
What you refer to as a "serial port" in Linux is actually a serial terminal with many software layers.
Study Linux serial drivers, and the termios man page for salient functions that need to be emulated.
And you have not even considered how to factor in the USB component of the communication path.
At FPGA:
SoftwareModule <= ttyACM => HardwareModem
...
My computer with ubuntu does not have ttyACM
A /dev/ttyACMx device node is only created when a USB serial gadget is connected to the host.
So it's not surprising that you cannot find such a device node.
What I need to achieve at my computer:
SoftwareModule <=> MyModemEmulator acting like a fake UART
You have stated the issue poorly, since you (misguidedly) think that a "fake UART" (integrated with your "MyModemEmulator") is the appropriate solution.
Do not try to emulate both a serial terminal and an external modem on the Ubuntu host, since you are "quite new to programming at linux and serial ports" and the task of accurately emulating a serial terminal is risky and expensive.
What your goal should be is:
SoftwareModule <= ? => MyModemEmulator
and the question is "what is needed in the middle to interface these two units?".
IOW you have posted an XY problem.
There are a plethora of SBCs (single board computer) that have a USB gadget port and can be configured as a USB serial gadget that uses CDC ACM.
Since the actual "hardware modem on an FPGA" will use a USB CDC ACM connection, you should consider using an actual /dev/ttyACMx serial terminal, and emulating just the external device ("hardware modem") with a SBC.
In other words, instead of trying to achieve:
SoftwareModule <=> MyModemEmulator + fake USB serial terminal
it should be much easier to use existing interfaces and implement:
SoftwareModule <= USB => emulated HardwareModem
with a SBC running your Linux application for modem emulation using /dev/ttyGS0 (a USB serial terminal on the gadget end).
By using an actual USB CDC ACM connection and not implementing the "fake USB serial terminal", this approach eliminates an entire layer of SW+HW emulation and its possible false test results.
Addendum
If the use and/or cost of embedded Linux on a SBC concerns you, then there is an alternative scheme to emulate the "hardware modem" on your Ubuntu PC host instead of the SBC using a USB-to-RS232-to-USB connection.
Acquire a pair (i.e. quantity 2) of USB-to-RS232 adapters and a (very short) null-modem cable.
Connect the DB-9 ends of the adapters to the null-modem cable to make a single cable with both ends having a USB male type-A connector.
Plug one adapter into the PC to create the /dev/ttyUSB0 device node. Treat this as the equivalent to /dev/ttyACM0 for your SoftwareModule.
Plug the other adapter into the PC to create the /dev/ttyUSB1 device node. Treat this as the equivalent to /dev/ttyGS0 for your emulated "hardware modem".
Develop, execute, and debug your emulated "hardware modem" on the Ubuntu PC host (without the unnecessary task of "creating a fake serial port").
So I have this program under embedded linux written with Qt and using Qt Bluetooth module (with some bluez help over it's D-Bus interface) for all sorts of bluetooth operations.
Now, I want to be able to find bluetooth adapter and use it when program is already running (use case: there was no adapter on startup, but then it was plugged in via usb).
My problem is that QBluetoothLocalDevice (which I'm using heavily) seems to be not working if there was no devices on a startup. Class is being created, but all calls are unsuccessful.
I was testing this by creating new instance of this class when new adapter is up and running (but was not on a startup).
Any advice on this?
Also, what's the good way for monitoring BT adapter availability with Qt and/or bluez? Ideally, I would love to have some signal (over bluez's DBus, I guess) when new one is becoming available-disabled.
Currently I want to create a qt application on my Desktop that say, has 3 buttons. These 3 buttons can change certain variables for my device, which will be connected to the desktop with a microcontroller.
I want my desktop application to be able to communicate with the microcontroller. For example, clicking a button might flip a certain boolean variable and the microcontroller will adjust accordingly.
I have no idea how to start and what sort of questions I should be asking and how to tackle this at a high level.
Thank you.
My desktop is a macbook pro retina 15-inch 2014 and my microcontroller is either an Teensy, or an Intel Atom.
I don't know what type of microcontroller you are using, but if it has support for UART you can use the QSerialPort lib (http://doc.qt.io/qt-5/qserialport.html) to send data using a serial port.
In case of an arduino, you can send messages using this lib directly via the USB emulated COM port. If it don't have USB emulated COM port, you should use a serial adapter (an Arduino board can play this role).
The first thing to look at is what communication buses are common between your desktop computer and your microcontroller. Does your microcontroller have USB or ethernet capabilities? Does your microcontroller have expansion boards for WiFi or bluetooth support? Do you have access to an I2C bus in your desktop PC?
Depending on the answers above, if your microcontroller and your computer do not share common communication buses, you might have to use intermediary hardware, for instance, you might want to use something like the FTDI USB (on your desktop) to UART (for the microcontroller) cables, you can find those here: http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm
In that case I'd recommend using a cable with VCD drivers, so the cable appears as a Serial port to your computer, which you can access in QT by using QSerialPort (http://doc.qt.io/qt-5/qserialport.html)
There would be other similar solutions, but I'd say that, if there are no shared buses between your microcontroller and host, this would be one of the most universal. Maybe if you specify your microcontroller or embedded board We could help a little more.
i am electronics and communication engineering student. i am working on a project in which a microcontroller send data to serial port of computer (asynchronously).
i currently learning wxWidgets for my GUI work.
my question-
is it possible to do using wxWidgets to get data and display. is it very difficult to implement this.
i search for it but not get direct answer that how to implement this. so suggest me what i need to read for this. and what alternative available to do this. i use windows 7.
i also need to upload this data to web server (it is needed later)
wxWidgets, to the best of my knowledge, does not implement serial I/O facilities. There are other libraries available that provide this. One of the best choices is probably boost::asio (see http://www.boost.org/doc/libs/1_40_0/doc/html/boost_asio/overview/serial_ports.html)
wxWidgets is a cross-platform GUI framework.
Reading a serial port is nothing to do with the GUI, and not cross platform.
So wxWidgets has nothing to do with reading serial ports.
You can read/write from/to a serial port using the windows API.
CreateFile opens the port
ReadFile reads data from the port
Difficult? Kinda!
I've never used it myself but there is wxCTB.