Flasher - Virtual COM Port

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Virtual COM port (VCOM) is a technology used to replace the traditional COM ports on modern PCs and laptops. From the hosts perspective, there is no difference between a "real", physical COM port and a virtual COM port. The virtual COM port presents itself in the same way and offers the same functionality. The virtual COM port is a COM port via USB. In case of the Flasher, the virtual COM port is used as a communication channel for accessing the Flashers' terminal.

Note:
Flasher's VCOM port purpose differs compared to the VCOM port of J-Links. Refer to J-Link Virtual COM port for more information.


USB to Virtual COM Port adapters

Most modern PCs and notebooks no longer provide COM connectors on their mainboards due to the large size factor of the COM port connector and the fact that very few consumer users have any use for them. The typical replacement is a a USB device to show up as a COM port at the PC. These USB to COM adapters that have a USB connector on one side and a COM connector on the other one allow retrofitting a modern machine with a COM port Once the adapter has been connected to the PC, a new COM port will show up which can then be used as a normal COM port by terminal applications etc.

Identifying Virtual COM Ports on a windows machine

Windows does not always assign the same COM port number to a virtual COM port. To identify the current COM assignment, the Windows Device Manager can be used:

Flasher VCOM recognized as COM.png



Connection

PuTTY settings for Flasher's VCOM

Flasher's VCOM port is always enabled. When a Flasher is connected to a PC, the operating system will recognize the VCOM port as a normal COM port.
Any terminal applications (such as PuTTY or hTerm) can connect to Flasher's VCOM port in the same way as any other COM port.

Terminal settings necessary to connect to Flasher's VCOM port:

  • Baudrate: Any
    • In contrast to J-Link's VCOM port, the configured baudrate does not matter in this case.
      Any baudrate will work, and therefore the setting will not affect the actual communication speed of the terminal.
  • Data bits: 8
  • Parity: None
  • Stop bits: 1

Example

Flasher's VCOM port is used as a communication channel for accessing the Flashers' terminal. This allows users to send commands, retrieve information, and interact with the device in a simple serial-terminal environment. The following example uses a serial connection via VCOM to access the Flasher's terminal and list the files on the file system:

Flasher VCOM for terminal.png


Performance

Actual communication throughput depends solely on the Flasher’s internal configuration and is not limited by the terminal’s selected baudrate.

USB class

For VCOM, the USB CDC-ACM class is used.