Open Flash Loader


Open Flash loader is an implementation in NuttX that bridges the device drivers in NuttX with the programming methods of a flash loader in J-Link. It allows J-Link to program any supported NuttX device driver.



`CONFIG_DISABLE_IDLE_LOOP is used to disable the idle loop in NuttX. `CONFIG_SYSTEM_OFLOADER` is used to enable the Open Flash Loader. `CONFIG_SYSTEM_OFLOADER_TABLE` is used to configure the flash device first parameter is the device name, second parameter is the start address.

The reference configuration “stm32f429i-disco:ofloader” is designed to be used with the STM32F429I-DISCO board in NuttX, enabling the Open Flash loader functionality. This configuration allows the J-Link flash loader to program the NuttX image onto the STM32F429I-DISCO board.


  1. Build NuttX with Open Flash Loader.

  2. Configure the Jlink xml file. like

        <ChipInfo Vendor="STM32NUTTX" Name="NuttX" Core="JLINK_CORE_CORTEX_M4" WorkRAMAddr="0x20000000" WorkRAMSize="0x10000000" />
        <FlashBankInfo Name="Storage" BaseAddr="0x00000000" MaxSize="0xffffffff" Loader="/home/ajh/work/vela_all/nuttx/nuttx" LoaderType="FLASH_ALGO_TYPE_OPEN" AlwaysPresent="1"/>
  1. Use JLinkExe -if SWD -speed 4000 -device STM32NUTTX, then loadbin /home/ajh/work/nuttx.bin 0x08000000, we can flash nuttx.bin to /dev/flash


1.If you need to implement the ofloader on a different board, you will need to read the wiki <> and refer to the implementation of “ofloader.ld” linker script located in the “boards/arm/stm32/stm32f429i-disco/scripts” directory. This linker script defines how the different sections of the NuttX image are placed in memory. You should configure the corresponding sections to be located in RAM, where the J-Link can write the image correctly.

2.When running the ofloader, J-Link disables any interrupts by default. Therefore, currently, it does not support programming devices with interrupt-driven drivers.

3.Due to limitations of J-Link, the ofloader image file cannot exceed 64KB. It is essential to be mindful of this constraint during programming.