J-Link-OB-RX621-ARM-SWD

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J-Link OB is a single chip microcontroller "on-board" version of J-Link. It is designed to be a low-cost, single chip, on-board debug solution for evaluation boards. There are various J-Link-OB implementations available, which are based on different devices. This article refers to the J-Link-OB-RX621-ARM-SWD which is a J-Link-OB based on the Renesas RX621 series devices which is capable of debugging ARM based target devices like the Renesas Synergy series devices. For more information about what J-Link-OB, please refer to https://www.segger.com/jlink-ob.html

Enumeration under Ubuntu running in VirtualBox fails

Problem Description

Under special circumstances and with a special setup, it could happen with older bootloader versions of the J-Link-OB-RX621-ARM-SWD, that enumerating via USB in a Ubuntu environment running in VirtualBox failed and J-Link was not detected properly under Ubuntu. SEGGER has reproduced the issue with the following setup but it may also occur under other constellations as well:

  • Host OS: Win7 64-bit
  • VirtualBox: Version 5.0.18
  • VirtualBox guest OS: Ubuntu 14.04 LTS

The problem only occurred if the J-Linkk was enumerating directly inside the VirtualBox guest OS. If it initially enumerated under the host OS and was connected to the VirtualBox guest OS later on, it worked fine.

Affected Evaluation Boards

This J-Link-OB model for example is used on the Renesas Synergy development kits.

Replacing the Bootloader (Fix)

As the fix requires to replace the bootloader of the J-Link OB, which can result (even if very unlikely) in a unusable J-Link-OB, the fix for this is not automatically applied when a new version of the J-Link software is installed. In the following it is described how to replace the bootloader of the J-Link-OB.

The following should only be done if you are affected by this problem. Please make sure that power supply to the J-Link-OB is stable. Unstable power supply during bootloader replacement can result in an unusable J-Link-OB.

Download and install J-Link software V5.41b or later:

Start J-Link Commander and perform firmware update if asked for

Execute updatebtl command

SEGGER J-Link Commander V5.41b (Compiled May  3 2016 13:50:50)
DLL version V5.41b, compiled May  3 2016 13:50:27

Connecting to J-Link via USB...O.K.
Firmware: J-Link OB RX621-ARM-SWD V1 compiled May  3 2016 12:18:23
Hardware version: V2.10
S/N: 708000000
VTref = 3.300V


Type "connect" to establish a target connection, '?' for help
J-Link>updatebtl
O.K.
J-Link>