The 3G USB modem I'm using creates /dev/ttyUSB which I can send AT commands to it as a serial port.
But is there another API to communicate to a USB Modem? is it always working as a serial COM?
How to get the API like AT command list from different vendors?
I'm writing a program in C to make calls, data test and so on but the AT commands doesn't always work, many times I needed to unplug/plug the modem to get it to work again so I thought there could be another way to do that.
Debian Linux is the platform by the way.
Appreciate your answers.
Related
As a web developer, I am new to USB and gadget development. I am creating a Windows Desktop application that communicates, using the Node-USB library, with a USB Device. To start, I am trying to create a mock USB device using Linux on my Raspberry Pi 4. I have set it up to boot as a USB device using this script, which is based on this guide, which sets the usb provider/vendor IDs, a rndis function, and more. Windows recognizes the device when plugging it into the computer, and I am able to open a connection to it using the NodeJS library.
I am now stuck on how to configure the device to set up a function that simply listens to data sent to it on a "bulk in" endpoint from the host, and echo it back automatically to the host, so that the Windows application receives it. I have been advised that there are many scripts available to set up a simple "demo" gadget like this on Linux, but I cannot find any.
It's not clear to me,
How to set up a usb function on the device to listen to a bulk "out" endpoint
How to set up a "driver" or a custom-made application to "listen" to the aforementioned function
How to make the listening application itself. The node-usb library says it's made for communicating with USB devices, not for devices itself, so it seems I can't use it?
Is there a simple bash script or built-in linux command that can automatically echo data to the host from the "in" endpoint?
I'd appreciate any guidance to point me in the right direction!
You need to write a USB function driver in kernel or use functionfs to do it in userspace. Either way you'll need to prepare USB descriptors which are presented to the host during enumeration (when your device is being plugged in) and then handle incoming USB requests on registered endpoints.
To setup one of the drivers already existing in kernel you can do it through configfs or using libusbgx wrapper library. There are also legacy function drivers which activate automatically after loading the module.
The node-usb library is wrapper for libusb, which is host-side library. So you're right, you cannot use it to create device-side function driver.
There is f_loopback function in kernel which does exactly what you need. This is probably the best starting point if you want to create your own USB function driver.
What I want to do:
An AI program on a host machine, reading inputs from a camera sensing the screen of the target machine and outputting controls to the target machine via USB connection--programming the host machine's USB host as a USB peripheral connected to the target machine.
What I want to do step by step: (is it possible to implement the steps below?)
Have a host machine A and a target machine B.
Connect A and B with a USB 3.0 Type-A male-male cable.
The USB connection shows up as an HID keyboard device on B.
Write code to simulate key presses on A that sends to B.
(Eg. calling press('F') on a program running on A would type F to B's input)
It shouldn't require any program installed on B.
What I already searched:
USB 3.0 Host to host connection is possible:
https://superuser.com/questions/795053/how-do-i-connect-two-computers-using-usb-3-0
USB 2.0 Host to host connection is impossible:
https://superuser.com/questions/99274/how-to-connect-two-computers-with-usb
Similar questions asked without the assumption that USB 3.0 Host to Host connection is possible:
https://superuser.com/questions/1128365/simulate-usb-keyboard-from-machine
Setting up a computer to act as an HID device connected to another computer via ps/2,usb or another wired connection
https://superuser.com/questions/507921/computer-to-act-as-keyboard?rq=1
Suggestions in ascending order of feasibility:
USB Gadgets
You are using linux, so the default way would be to create/configure/load a gadget driver. Have a look at this tutorial, though for a raspberry, should work on your PC too. However, I could not find any information regarding the use of USB3 - the tutorial assumes your host is using one of it's OTG ports, which your PC most likely does not have. So whether this works with your USB3.1 Type-A-to-Type-A connection you'll need to test.
USBIP
The idea of sharing USB devices (not just keyboards) is not really new. With USBIP you can "export" any local USB device to the network, and your client will need the client-side USBIP driver to access the keyboard.
Dont bother with USB at all, just use Ethernet
I'd simply write two userland scripts/programs that send/receive+execute the keystrokes. Very easy to implement, you're probably familiar with python anyway.
If you absolutely cant have software installed on the client-PC and your Type-C-to-Type-C connection doesnt support USB Gadgets, there's another way. It basically involves the use of two USB-to-serial adapters (~15$) and a serial cable. While this wont be enumerated as a keyboard, but rather as serial port, it's the lowest-effort solution to transfer data without additional software on the client. Both computers will just do file I/O. If your computers still have COM-ports, you can even omit the serial converters!
I'm currently working on a device which is able to work as a keyboard and communicate via Serial with a self-written software.
Now I have to install serial drivers (from Arduino) on different computers if I want to communicate with my application which I actually want to avoid.
Is there any other solution to solve this problem? Is it possible that my microcontroller works as a keyboard AND is able to send and receive data as HID device?
Thanks and greetings!
I actually do something similar with a 32u4, but it receives its serial over the built-in UART. I do this because it's linking between two separate systems. If it were only one system I could implement a 2nd interface. (Don't forget, a USB HID device must have an IN endpoint even if you are not using it.) Or you could just throw a $2 USB/TTL converter on and do it the same as I did.
I am using a huawei e355 usb modem on linux. I would like to send my usb modem texts from my cell phone and would want my usb modem to store it in some log file and may be communicate back. How do I go about doing this?
I went through a lot of articles but they were more about setting up the modem rather than using it in this particular way.
The best option for your needs would be Gammu. You can download it here http://wammu.eu/. You can also get it over your paket manager.
There is a python API available which makes interacting with texts easier.
For your needs I would recommend you run the gammu-sms daemon (gammu-smsd) and have a script which interacts with the contents of your sms. Check the RunOnReceive variable in the /etc/gammu-smsdrc file.
Try http://www.question-defense.com/2010/07/27/use-minicom-for-linux-modem-dialup-at-command-testing.
This allows you to send and receive texts from the modem; you can then set a callback for what to do once a text is received. I'm currently working on something along these lines, too, so I don't have a complete answer, but this should get you started.
I have two legacy machines connected to a Linux box with USB using the ftdi_sio driver, to /dev/ttyUSB0 and /dev/ttyUSB1. The Linux box is relaying and analyzing the traffic between the machines. When the Linux box boots up, the machines are connected to the files pretty much randomly. The problem is to know which one is which.
I could just ask the devices, of course, but I'd like to avoid the risk of malfunction due to sending wrong data to the wrong device. Is there a way to figure out, for example, the id of the device connected to a tty file?
Check this Using Linux USB page.
/proc/bus/usb/devices lists information about the devices currently attached to the USB bus. This is very useful when trying to figure out if the device is correctly enumerated.
Maybe you can use the output from lsusb -v and look at iProduct + iSerial to determine the order the devices are attached.