Currently I have a server, that communicates with a projector through a RS232. The server opens a com port when the projector is connected. The same happens to any PC when a certain type of device is connected through the USB (lets say an Arduino for example). What I want to do it basically replace the projector with a PC/Arduino/Raspberry without the server noticing anything. That would mean the server will recognise the connected PC and open a COM port for it. What do I need to do on the PC so that it automatically opens a com port on the server? I guess there is something very basic that any printer, Arduino, projector etc does, that computers recognise it as a "com port device".
P.S. Doesn't matter the OS on the PC, I just need to make it work and then implement w/e I need to do with the established communication over the port.
P.S.2 I've searched a lot about it, but probabl I am doing it wrong, because I didn't find my type of question anywhere.
COM ports are basically hardware that is detected by the system. Let's say, if an Arduino is connected to a PC, it has its onboard USB to TTL converter which can be found in the device manager(if using windows). Similar USB to TTL converters are there in the market like CP2102, PL2303 which acts like a COM port even if no device is connected further to it. it may be possible that the program you are using(as you referred server) may be sending some data over the serial port and verifying the hardware.
What you need to do to replace it is, first of all, find the baud rate at which the communication is going on, then, listen over the serial lines which machine is sending which message in the sequence(there must be a handshake as I mentioned earlier), if a complicated algorithm is not used by the device, you can simply mimic the device by sending same messages over serial.
Related
I am working with someone using Mbed and a LPCXpresso11U68 board.
I'm not intimately familiar with this particular board, but it has two USB connectors on it, one for the OpenSDA-ish debugger, and a second one is a direct connect to the CPU. I can connect both of these ports to my PC and attach a terminal emulator to each of them, and both ports show output (with a small installed program running on the board).
The device manager shows me that one port (COM51) is using "mbed Serial Port" driver and the other port (COM52) is using "Mbed Virtual Serial Port.
So far so good...
There is a reset button on the board. If I press that button, the port that is attached to the PC using the Mbed Virtual Serial Port driver (in my case COM52) stops operating. The other port (COM51) just restarts cleanly.
The problem I'm having is that after I exit the terminal program (note this happens with both TeraTerm and uCon), if I attempt to reconnect to that port, its not in the list of available comports. Strangely thought, it is still present in the Device Manager.
The only way I've found that I can clear this problem is to unplug/plug that usb cable (COM52) or issue a BREAK condition to COM51 (which AFAIK, resets the board).
I am the writer of uCon and I'd like to be able to detect this (which I can), and also be able to restart the comport connection without any other manual intervention.
One final note: apparently this is not specific to the LPCXpresso11U68 board; my guess it is some issue with the Mbed Virtual Serial Port driver.
Anyone have a clue what may be going on here?
I would like to develop my own modem for a custom communication network that will be detectable on the serial port by PC automatically. What I'm uncertain about is the protocol part of the AT commands and how to make it work seamlessly so that computer will detect the modem automatically.
I plan to use ftdi UART to USB converter to interface my microcontroller with the PC using standard serial interface. The PC will then use AT commands to communicate with the microcontroller that will in turn connect to another microcontroller over radio tranceiver and establish a two way serial connection over radio. The idea is that the PC on the other end will run PPPD and listen on it's own modem connection for incoming call and then bridge the connection with it's other internet interface that is connected to internet. The first computer will get it's own IP address using PPPD and will be connected to internet over this custom microcontroller based modem.
But how do I implement the communication protocol between my controller and PC? What commands do I absolutely need to implement? How do I make sure that the computer recognises my controller which is connected over ftdi usb to serial adapter as a functional modem?
Where can I find a speciffication of the minimum command set that is required of a modem?
In practice linux usually discovers a 3G modem automatically for example. Does that have to do with the actual USB identifier of the modem? Is it possible to have linux automatically discover an ordinary serial port modem? I'm thinking that the modem will be sending an AT idle ping repeatedly when it's plugged in so that linux should be able to detect it.
I have 16 Arduinos that are in very tight spaces and hard to get to when I need to reprogram them with my FTDI cable. I would like to have or create some sort of centralized place where I can connect my FTDI cable, make some sort of selection (switch of some sort), which will then connect the pins my cable is on to the selected arduino.
Does anyone have any thoughts on how this can be accomplished? I've toyed with transistors, but that takes a lot of them and didn't quite work.
Are there any premade solutions that are out there that I have yet to find?
Thanks very much!
Here is a thought! TCP to Serial.
Sound complicated.
Not really.
Note from AVRDUDE's manual the following
For programmers that attach to a serial port using some kind of higher
level protocol (as opposed to bit-bang style programmers), port can be
specified as net:host:port. In this case, instead of trying to open a
local device, a TCP network connection to (TCP) port on host is
established. The remote endpoint is assumed to be a terminal or
console server that connects the network stream to a local serial port
where the actual programmer has been attached to. The port is assumed
to be properly configured, for example using a transparent 8-bit data
connection without parity at 115200 Baud for a STK500.
With this, One could place your Arduino's behind your choice of TCP to Serial Server. Which is available in several forms. Cisco has a gang TS (but that is expensive, unless used). lantronix (and others have single end point devices. But then for Linux, there is "Net2Ser" which can serve up all your ttyS (aka Serial/COM ports).
With the later you could use a raspberry or TP-Link TL-WR703N (
In the latest IDE 1.5.6r2 add one entry for each TCP-to-Serial Port to ./Arduino/hardware/arduino/avr/programmers.txt file. While replacing the IP and Port with corresponding values.
TCP2001.name=TCP 2001
TCP2001.communication=serial
TCP2001.protocol=stk500v1
TCP2001.program.protocol=stk500v1
TCP2001.program.tool=avrdude
TCP2001.program.extra_params=-Pnet:192.168.1.100:2001
TCP2002.name=TCP 2002
TCP2002.communication=serial
TCP2002.protocol=stk500v1
TCP2002.program.protocol=stk500v1
TCP2002.program.tool=avrdude
TCP2002.program.extra_params=-Pnet:192.168.1.100:2002
...
Additionally change "protocol" to "upload.protocol" the following line in ./Arduino/hardware/arduino/avr/platform.txt
tools.avrdude.program.pattern="{cmd.path}" "-C{config.path}" {program.verbose} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{build.path}/{build.project_name}.hex:i"
to
tools.avrdude.program.pattern="{cmd.path}" "-C{config.path}" {program.verbose} -p{build.mcu} -c{upload.protocol} {program.extra_params} "-Uflash:w:{build.path}/{build.project_name}.hex:i"
With this you can use "Upload Using Programmer" with the selected programmer to send over TCP, rather then use the Upload.
That all said, it will only work on Linux.
avrdude: ser_open(): network connects are currently notimplemented for Win32 environments
I want to know some general communication strategies, which should be followed for a communication via COM (serial) Port.
I can read/write at the port, also can list all the available ports on the machine. I'm using Qt C++ with QSerialDevice. For testing on a windows machine with no physical serial port, I'm using VPSE (virtual port)
Typical Flow (assumed):
List all the available serial ports of the computer.
Find out at which port my device (micro-controller) is connected - how to do it?
Device found.
Start a thread for reading from the port, another thread for writing it.
Safely close connection
Finding out at which port the device is connected sounds challenging to me. How to achieve it? I guess, I will send a HELLO message to each ports, if my device replies a specific per-defined reply message I can be sure my device is connected at that port. Can I?
Also I think, to seperate threads are necessary because at any time I may receive message from the Micro-controller device.
Thanks for helping :)
I'm creating a simple device that sends data to a Windows PC over serial COM ports.
I'd like the software to be able to scan the available COM ports until it recognizes the device. The problem is, if the PC tries to initiate the handshake with a device other than mine, it may interpret the commands [wrongly, of course].
The only solution I see is for my device to periodically broadcast some sort of identifier, perhaps 5 times per second or so, so the application only needs to listen for that identifier rather than risk corrupting another device also connected to a COM port. When the application loads, it listens on each available COM port until the device is recognised. Does this sound reasonable?
Thanks
IMO whatever the direction on which you initiate the handshake, the problem will be the same.
If you send your handshake from your device and another application on your PC is listening to the corresponding serial port, it also has risks to badly interpret the data you are sending.
So I would say that software on both side should be protected against incoherent data they receive from the outside.