Da Usb Vcom Port

[Bok Wykes]

Howthe mobile phone (that is off, but had been just plugged into USB) informs the Windows PC (with installed drivers "MediaTek PreLoader USB VCOM port" and "MediaTek USB Port") how to identify itself: as device - "MediaTek PreLoader USB VCOM port" or as - "MediaTek USB Port"?

When you plug in a MediaTek phone, it will turn on, but not fully on. The boot ROM will run, which will run the preloader, and depending on implementation, either show the charging animation or starts the Linux kernel and enters into a mode called kernel power-off charging (KPOC) that shows the charging animation. The devices you're seeing are associated with the first two stages. Both devices are used for downloading firmware to the phone, but they represent different stages and support different command sets. MediaTek USB Port is created by the boot ROM, and MediaTek PreLoader USB VCOM port is created by the preloader (it runs after the boot ROM and does further hardware initialization).

Usually, only the preloader device would show up upon plugging the phone in, but it seems in your case the phone might be configured to enter the boot ROM's download mode, and if it doesn't see a connection, to continue into the preloader, which will offer another download mode. It's also possible that there is some sort of issue with the preloader that causes the phone to reset back to boot ROM to start an emergency download mode.

When I power up with JP3 in place a USB drive opens on my desktop and shows the file firmware.bin with a size of 65.5 KB and a modification date of 2/6/2009. I delete this file and copy the firmware.bin file downloaded from the NXP site, which is 9.2 KB with a modification date of 4/25/2018. (I've tried to copy using both drag and drop, and via the cp command at the Linux terminal).

Then I power down the board, and power it back up with the jumper still in place, and it appears that the original file with the same size and creation date are still displayed. I.e. It appears that the copy was not actually performed. If I subsequently power down, remove the jumper and power up again, I still do not see the port enumerated in the /dev directory.

I attached jumper to JP3 and connected the board to my Windows machine. I installed the Windows drivers and updated the firmware according to the driver instructions. After removing power and removing JP3 and re-applying power, the com port enumerated under Windows.

I then powered the board down and transferred to my Ubuntu machine. When I powered the board it appeared to enumerate but I couldn't find a ttyUSB comm port. However, when I ran the MCUXpresso IDE, the IDE was able to connect to the debug port and I was able to run the Blinky demo under debug, and was able to single-step etc. So it looks like everything works.

I am using LPC-LINK2 with LPCXpresso845MAX board (for now). I could have used the 845MAX's built in 11U35 for SWD and VCOM but I choose LPC-LINK2 because that will be the board I will use when I design my own board with LPC845.

So setting up LPC-LINK2 in DFU mode and disabling 11U35 (by shorting JP1) on 845MAX board, I am able to load and run the code with MCUXpresso IDE. However I have no success in getting the VCOM working. In my test application, I have redirected the printfs to UART0 on 845MAX board which is available on J2 pin 7 and 8. And I am sure that the prints are coming out on these pins as I am able to connect an external USB serial port dongle and get the prints on my Teraterm console. However when I connect LPC-LINK2 uart pins which (I believe) as per schematics are routed on J3 pin 7 and 8 (UART2_RXD, UART2_TXD), I don't see output on console.

Sorry but we wont be able to provide that support on LPC-Link2, but will be sure to address in future debug probe designs. The LPC-Link2 is still a universal debug probe (VCOM is orthogonal to SWD/JTAG debug), but I agree this is an unfortunate limitation.

Thanks for your response. I understand your point of view as VCOM being orthogonal to SWD/JTAG. However 11U35 on various NXP evalkits supports both SWD and VCOM, hence raises the customer's expectation for LPC-LINK2 being universal debug probe.

I am looking to get a USB interface device to work on a Vcom port. The device is this SoundFX USB Decoder Programmer. It talks to a Model train layout using this software Any help would be great if you need more info please let me know and I will Help the best I can.

i dont think i installed JMRI right as i can not fine the program anywhere to launch it. i see the JMRI DIR but no launch program. i used the install guide but i must of missed somthing. should i delete the DIR from the PC and try it again? dont know the best way to go about that

The Launcher is the script file named PanelPro in the JMRI directory.

Can you right click it, then move to permissions tab, and check mark the box on for allow executing file as program.

Once done, try double clicking the PanelPro file and selecting Run to test.

Hmmm, I am not sure. I have never used that software and have no history with it. Does it require that USB device? If it does, I can not test it.

Looking at the Installation Instructions does not yield any Ubuntu versions.

The Screenshots look a lot like an older Ubuntu version to me.

The java version it requires is quite low... And perusing the site, the only date I can find on Ubuntu Products is for 2008. It is possible that Ubuntu 20.04 / 21.04 is too new for it... It's worth finding out sooner rather than later.

There is a FAQ page.

It does link to another users site that describes how he installed it on Fedora - but this gives a 404 error.

The other guide it lists for OpenSuse references removing 32bit (i386)files.

While we are perfectly willing to try to help; it may be discussing this with users of that software in Current Times may be more fruitful.

The problem is that i do not know how to get its corresponding COM port number assigned to be able to communicate with that specific USB device since there are several similar devices (having equal VID and PID but without Serial Number) connected to a PC at the same time.

I will use a TestStand sequence running 2 threads to communicate to both USB devices (having their hardware locations got as mentioned before assuming the physical connection/wiring will be always fixed) but their COM ports assigned by Windows are required to communicate with them.

COM ports are assigned in chronological order. So if you plug one after the other, you'll get COM3 then COM4 (assuming you already have 1&2 on your mobo). But on reboot, the order may be different, _but_ it should be stable between reboots. So, turn off, plug them in, reboot, note the order, reboot again, verify it stays the same.

Finally, i searched into the Windows Registry Editor to find the "PortName" of the device of interest connected into an USB port to get the complete path to access this registry programmatically as follows:

I am unable to go online with DirectLogic PLC, which is connect by serial RS-485 interface to the Ewon Flexy COM port. I am able to create tags in the flexy home page and they respond as expected, so the serial communication is not the problem.

The PLC has two serial ports, I am able to plug in RS232 Cable directly from my computer to Port#1 and successfully go online. Port#2 is connected by RS485 to the EWON. I have tried connecting my computer with LAN cable to EWON and go online with VCOM but no luck. There is no ECatcher Involved (so far).

I have a wide variety of VCOM devices (FTDI, CP210x, etc) that my program interfaces with, but I need to confirm they are in fact those devices before I begin talking to them. FTDI's D2XX library allows me to pair up the Product/Serial strings with COM number, but I really need a generic solution.

To be clear, I need the USB string descriptors for Product, Serial, and ideally Manufacturer as well. Note these are not the same as the VID/PID numbers, but actual strings. It is okay if I have to get the strings first, and then figure out the COM number for it later.

Look at the USBView sample in the WDK. If you are unfamiliar with this, simply run it - this tool walks the entire USB tree on the system and prints out information and descriptor listings for each device.

In your case, I'd start at the RefreshTree() function in this sample, you can then follow the code to see how it enumerates the devices. For each device that you find you can look at the string descriptors.

Once you have the VID/PID/Serial Number you should be able to look up the port number in the registry. For example, the CP210x port number will be located at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB\VID_10C4&PID_EA60\0001\Device Parameters\Port Name in the form of "COMxx" (where VID=10C4, PID=EA60, serial=0001). If you know what the VID/PID is for your device you could skip the USB search and simply parse through the registry to get all devices of that type to discover their COM port numbers.

You can also get a list of all COM ports on the system here: HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM. Values will be listed according to their type, so a real serial port will show up with a name \Device\Serialn and data COMxx, a CP210x will show up with a name \Device\Silabsern and data COMyy, etc. You can use the name to filter which type of device a COM port belongs to.

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