I'm trying to connect two arduino unos with ethernet shields with each other via crossover cable.(codes taken from server client) Both of them works when I connect them to a PC separately, however they can't communicate between each other(No lights except red on the shield lights up, connection fails). However it only works if I plug all of them in the switch. every device has static ips and the same subnet, but an interesting thing is that if I unplug the pc from the switch, arduinos stop communicating, even if the pc has a different subnet assigned.
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I have gone through several links online but I have not found any appropriate solution to it. I am wondering if there is a way to connect an Arduino with WiFi without using any shield or any other external hardware. My laptop is connected to WiFi and the arduino board is connected to the laptop with an USB cable. I want to access/run the data for the Arduino using WiFi. Is there a way to do it?
Hope my query makes a sense.
Thanks.
Let's restate your question for clarity - you want to share the laptop's Internet connection (e.g. via WiFi) with the Arduino connected to the laptop with a USB cable, with no additional hardware?
Assuming I restated it correctly, the Arduino's USB connection provides a virtual "serial port" for communication. This means you can use an "IP over serial" solution for Internet access. One such common and widely supported solution is PPP.
However, programing the Arduino with IP over PPP stack requires significant amount of memory and is probably an overkill for whatever it is you're trying to do.
You're probably better off designing a custom-tailored protocol for the serial communication between the Arduino and a small gateway program you can program and run on the laptop.
If you're bent on a complex solution that provides full Internet access to the Arduino, the steps to achieve what you're after are:
Program the Arduino with a TCP/IP over PPP protocol stack, running on the serial port. You'll probably need an Arduino MEGA.
Setup the laptop to be a PPP endpoint on the Arduino's serial port. For a Windows machine you can refer to this page for information on how to do that.
Once the PPP link is up, you can setup the laptop's OS to share Internet access to the PPP link.
I am currently connecting 2 PCs using serial communication and at this time I am using a USB to Serial converter, then a serial cable, then another USB to Serial converter going into the other PC in order to get the communication sent and received.
Is there a way to program the USB ports as COM ports without these converters and still be able to transfer the serial data over the USB using software rather than hardware, thus eliminating the need for the conversions and rather have just a straight USB cable to USB cable connection?
Thanks!
I was curious if anybody knows a way to connect two different computers together over a USB line and what API's exist to program this interface.
For Serial Ports its common to buy a "Null Modem" adapter to cross over the Transmit and Receive lines of the UART so that the computers can talk together. And then You would read and write them like normal windows files over special system files called "COM1", "COM2", etc.
I was wondering if there was an Adapter of some kind that could emulate this same behavior except for native USB protocol. I realize they have USB-to-UART adapters. That's not really what i'm interested in because the baud rate is very slow for uarts. I was looking for something with USB speeds to transfer from one computer to another that is not going over a network link such as ethernet or wifi.
This is what I have:
COMPUTER A<-->USB<-->UART<-->NULL_MODEM<-->UART<--->USB<-->COMPUTER B
Speed 110,000 Baud, whatever... to slow to transfer files... ok for text...
This is what I want:
COMPUTER A<-->USB<-->Crossover_Adapter<--->USB<-->COMPUTER B
Speed 480 megabits per second
Assuming this beast exists, how do you program it and where do you buy it?
The only solution that I know of is the "FTDI Chip USB-to-USB Null modem cable" that can transfer between computers two computers using USB ports at a rate of 3 MBaud (384 kbytes/s) That's a lot faster than using older serial ports with null modem cable that maxs out at say 115200 baud (14 kbytes/s). The FTDI chip cable can be programed in c/c++/c# just like a standard windows serial port by way of a virtual serial port.
http://shop.clickandbuild.com/cnb/shop/ftdichip?op=catalogue-products-null&prodCategoryID=92&title=Null+Modem+Cables
From Their Website:
USB NMC-2.5m
NMC In the era of legacy PCs with onboard RS232 COM Ports, it was
common practice to establish a simple communications network between
PCs using a cable popularly known as a Null-Modem cable. Typically,
such a cable would have DB9 female connectors on each end with the TX
/ RX and handshaking signals cross-connected so that the PCs could
communicate with each other via legacy COM ports.
On modern PCs the legacy COM Port connector is rapidly disappearing as
USB becomes the multi-function communication port of choice. However,
this presents a dilemma in application areas that previously relied on
legacy COM Ports for inter-PC communication.
A convenient solution to the problem is the FTDI USB NMC cable. From
the outside, this cable appears to be two USB type “A” sockets wired
together, however each of the USB sockets conceal a small PCB with a
FT232RQ based USB-UART converter IC plus support components inside.
The interconnect cable cross-connects the TXD / RXD data signals, RTS
/ CTS handshaking signals and interconnects the common GND reference
rail betwen the two converter PCBs.
When used together with FTDI’s supplied Virtual COM Port ( VCP )
drivers, the USB NMC cable may be used to establish inter-PC COM Port
based communication at baud rates of up to 3M baud. The standard USB
NMC cable p/n USB NMC-2.5m comes with an interconnect length of 2.5m (
8.2ft ) - other lengths may be available on request. Multiple operating systems are supported including Windows, Linux, Mac OS etc.
single cable
Another Alternative is to use Bluetooth which is also programmable just like a the older serial port.
I think I found the solution: Avnet Spartan-6 LX9 MicroBoard.
It has a USB on one end and an ethernet port on the other end.
http://www.xilinx.com/products/boards-and-kits/1-3i2dfk.html
I can put the fpga/microblaze-cpu in the middle to filter out traffic to make sure the link doesn't get hacked and maybe encrypted it as well.
Easy Computer Sync sells the null modem cable plus the data transfer software. The SW is versatile and easy to use. https://www.bravurasoftware.com/easy-computer-sync/ (I have no connection with other than being a satisfied user.)
I have a device connected to USB port via USB cable to my PC and in device Manager it says - > "XYZ corp Virtual COM port (COM A)"
Is this is same as Serial Com Port.?What is the underlying hardware under it both at device side and Host Side - a Uart or a USB or both at either end respectively?
It sounds like your USB device uses a driver that provides a serial port interface inside your computer. This means that other software can use the serial port APIs that Windows provides to connect to it and use it as a serial port. That software doesn't need to know the details of your USB device; it just needs to know about using serial ports in Windows. Windows ships with a driver that is often used to do this, and that driver is named usbser.sys. Your device might be using usbser.sys or it might be using some other driver.
The serial data is transferred via your computer's USB port and a USB cable. If you look at the signals on the USB cable, you will not see typical serial signals: you will see regular USB packets that just happen to be carrying that data needed for a serial port.
The USB device on the end of that cable might then translate that data into serial signals and act like a normal serial port, or that data might just be used directly inside the device. Without a link to the product in question, it is hard to tell you more than that.
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.