J-Link Multiple Flashloader

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J-Link features support for multiple flashloader per flashbank. Additionally to the devices where J-Link already has built-in support for multiple loader, the user may choose to add support for a different flashloader.

Use case

Having multiple flashloader for the same device can be useful e.g. if a SPI flashbank shall be programmed, but the default flashloader uses a different pin configuration compared to the hardware. In this case selecting a different flashloader with a compatible pin configuration can be the solution.

Selecting a specific flashloader

There are several ways in which the user may select one of the available flashloaders.

By default the first flashloader on the list of available loaders is selected.

Command line parameter

The device name of the used device can be extended with the flashbank address and the loader name.


-device "<DeviceName>?BankAddr=<FlashBankBase>&Loader=<LoaderName>"

Parameter Meaning
DeviceName The device name.
FlashBankBase The base address of the flashbank for which a different loader should be used.
LoaderName The name of the loader which should be used.


-device "STM32H743ZI?BankAddr=0x90000000&Loader=CLK@PF10_nCS@PB6_D0@PF8_D1@PF9_D2@PF7_D3@PF6"

J-Link Script File

With the J-Link Script File function JLINK_ExecCommand() a different loader can be selected.


JLINK_ExecCommand("DEVICE_SelectLoader BankAddr=<FlashBankBase> Loader=<LoaderName>");

Parameter Meaning
FlashBankBase The base address of the flashbank for which a different loader should be used.
LoaderName The name of the loader which should be used.


JLINK_ExecCommand("DEVICE_SelectLoader BankAddr=0x90000000 Loader=CLK@PF10_nCS@PB6_D0@PF8_D1@PF9_D2@PF7_D3@PF6");

J-Link web control panel

The J-Link web control panel features a GUI access to easily select a different flashloader. This method requires that a settings file has been specified for J-Link.

How to

Example for STM32H743XI
  1. Start the debug session with a settings file specified
  2. Open J-Link web control panel
  3. Navigate to the "Flash" tab
  4. Select a different loader for the desired flashbank from the drop-down menu
  5. Restart the debug session


In J-Flash there are two ways to select the flash loader:

Example for R7FA4M2AD
  • When creating a new project for a device with a multiple-loader-flashbank, the loader can be selected from the drop down menu.
  • With a existing project, the loader can be selected under Options -> Project settings ... -> Flash -> Loader

Embedded Studio

The SEGGER Embedded Studio IDE of course also supports this feature. You can use any of the methods above. One additional way is to set the loader via the Embedded Studio GUI in project options.

How to

  1. Open the project settings of your Embedded Studio project
  2. Go to: Debug > J-Link > Additional J-Link Options
  3. Enter the exec command DEVICE_SelectLoader as explained here
  4. Press OK twice in both project option windows to confirm the newly set option

Specifying multiple loader via XML

With attributes in JLinkDevices.xml files it is possible for the user to add their own flashloader to the list of selectable loaders. For more information, please see the JLinkDevices section of the Open Flashloader article.