Drivers Segger

  1. Drivers Services Mt
  2. Drivers Services Mn
  3. Segger Drivers
  • 1Enabling VCOM
  • 2Checking VCOM state
  • 3Linux specifics
    • 3.1ModemManager

I am new to nRF SoC and SEGGER. After installing all tools, I can build and run examples. I run into a problem to add and enable a nRF driver, like 'UARTE peripheral driver', what are the procedure and step to do that? I try to use the CMSIS configuration wizard to do that, but I found the followings in different examples as. EmWin Display Drivers A display driver supports a particular family of display controllers. The drivers can be configured by modifying their configuration files whereas the driver itself does not need to be modified.

The driver package provides the installation files for Segger J-Link USB Driver 64-bit. If you consider updating this driver package by Driver Genius, all you need to do is clicking the Update button beside this driver update. Driver Genius will install the driver automatically, smoothly and silently. It includes flash-programming algorithms for most MCUs, and Segger is very pro-active about updating their drivers to support the newest chipsets. It just works, and keeps on working, and it'll be there for you in several years time. The J-Link is fast. This video tutorial will show you how to create files or add existing files to your project. We will also talk about how to add and enable drivers to your pr.

In general, the VCOM feature can be disabled and enabled for debug probes which comes with support for it via J-Link Commander and J-Link Configurator.
Please note, that:

Drivers services mn
  • VCOM can only be used when debugging via SWD target interface. Pin 5 = J-Link-Tx (out), Pin 17 = J-Link-Rx (in).
  • Currently, only J-Link models with hardware version 9 or newer come with VCOM capabilities.

Via J-Link Configurator

Start the J-Link Configurator and configure the device to enable VCOM functionality by double-clicking.Under 'Virtual COM-Port', choose 'Enable' and click 'OK'. After that the device needs to be power cycled in order for VCOM to work.

Via J-Link Commander

Start the J-Link Commander and enter 'vcom enable'. After that the device needs to be power cycled in order for VCOM to work.

VCOM enable in J-Link Commander

Checking if VCOM is active can be done by opening the device manager. Connected devices with VCOM functionality will be listed under 'Ports (COM & LPT)'.

Testing VCOM functionality and speed

The VCOM functionality can be tested for by simply connecting the Tx pin with the Rx pin - creating a loopback that way - and starting a terminal application.This leads to the Rx pin receiving the sent data meaning that VCOM is active and working.

  • Create a loopback by connecting the Tx pin with the Rx pin.
  • Make sure pins VTref and GND are connected to J-Link. For testing we recommend VTref = 3.3 V.
  • Start a terminal application (e.g. HTerm) and establish a connection to the COM port.
  • Use an oscilloscope to visualize the signals sent via the Tx pin and the Rx pin.
  • Send data via VCOM using the given terminal application. Use the letter 'U' (01010101 in binary) to create a regular square-wave signal.

The oscilloscope will show the same signal sequence for both, the Rx and the Tx pin, confirming the VCOM functionality.The speed VCOM is operating at can also be determined with an oscilloscope, e.g. by measuring the duration of a single high state.

VCOM char 'U'


Many Linux distributions have the ModemManager application installed and running as a daemon by default. This daemon by default opens a connection to a CDC-ACM device (like a J-Link VCOM) as soon as the device has enumerated and starts sending AT commands over the device to the other side (usually a target MCU connected to J-Link). Depending on the target application, this may create problems because the target now receives unexpected data via VCOM. Fortunately, the ModemManager can be disabled for specific USB devices (filtered by VID and PID) via the Linux rules system (rules files).

Disabled by default for J-Link

For J-Link software installers V6.33i and later, the 99-jlink.rules file has rules that disable the ModemManager for J-Link-like USB devices.

Manually disabling ModemManager for specific USB devices

Drivers Services Mt


If for some reason it is necessary to disable ModemManager also for other USB devices or if the J-Link installer cannot be used on the Linux host, the rules can be specified manually. This is explained in the following:

Drivers Segger
  • Download 99-segger-vcom.rules (Right-click 'Save link as...')
  • Edit the PID / VID in the file to match the ones you want to be affected (leaving out the PID will affect all devices of the specified VID)
  • Open a terminal on the Linux host
  • Execute the following commands:
    • cd Downloads/SEGGER
    • sudo su
    • chown root 99-segger-vcom.rules
    • chmod u=rw 99-segger-vcom.rules
    • chmod a+r 99-segger-vcom.rules
    • ls -l 99-segger-vcom.rules
    • cp 99-segger-vcom.rules /etc/udev/rules.d/99-segger-vcom.rules
    • udevadm control --reload-rules
    • exit


Drivers Services Mn

From now on all devices with vendor ID 0x1366 (SEGGER) will not be touched by ModemManager anymore.

Finding out PID and VID

The VID and PID can be found out via the 'lsusb' command:

The format is <VID>:<PID>

Segger Drivers

Retrieved from ''
Comments are closed.