Difference between revisions of "Using J-Link VCOM functionality"

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== Checking VCOM functionality ==
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== Testing VCOM functionality ==
   
 
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.
 
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.

Revision as of 15:30, 24 November 2017


In general, the Viurtual COM Port(VCOM) feature can be disabled and enabled for debug probes which come with support for it via J-Link Commander and J-Link Configurator.

Note that 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.

Enabling VCOM

A small description of how to enable VCOM functionality for J-Link can be found on page 218 of the J-Link User Guide.

Checking VCOM state

Checking if VCOM is active can be done by opening the device manager. -screenshot-

Testing VCOM functionality

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.

Checking VCOM speed

The speed at which VCOM is operating at can be checked by using an oscilloscope to measure the Tx signal. This can be easily done by sending the letter 'U' as it translates to 01010101 in binary, creating a regular square-wave signal.