J-Link Flash Download

J-Link supports programming of memory-mapped QSPI NOR flash via the standard methods described before.
While in the beginning, SPI NOR flash was usually a custom connection and not standardized, with advanced MCUs and making the QSPI flash memory-mapped visible in the MCU address space,
it became a full replacement and even successor of parallel NOR flash. With J-Link, all features known from internal flash are also available in memory-mapped QSPI flash:

• Make flash behave like RAM in the debugger (e.g. writing in the memory window can be used to change constants in flash)
• Flash breakpoints (unlimited number of breakpoints when debugging in flash)
• Any IDE (e.g. GDB based ones) can easily download to flash without even the need to add some sort of custom flash algo in the IDE, as J-Link does all the work

Note: On many Cortex-M based devices, hardware breakpoints are not usable in QSPI flash, making J-Link + flash breakpoints the only real option to debug in QSPI flash on these devices.

The flash download feature of J-Link supports programming of external CFI-compliant, parallel NOR flash devices, allowing these devices to be programmed either directly from the debugger or through J-Link commander. For more information regarding how to setup the debugger / J-Link Commander for download into parallel (CFI) NOR flash memory, please refer to UM08001, chapter "Flash Download". For production environments, we recommend using J-Flash or Flasher ARM standalone.

Since these flash devices are not connected to the address and data bus directly and the connection to the CPU / MCU / MPU differs from device to device, a customized flash algorithm is necessary in order to program these flash devices. The flash algorithm is implemented using Open Flash loader. This can either be done by the customer or by SEGGER (request quote: sales@segger.com). With custom algorithms it is possible to program these types of flash devices via J-Flash and Flasher ARM. To program SPI flash memories directly via the SPI bus, there is J-Flash SPI.

In general, the J-Link DLL comes with a built-in device database that defines which devices are supported. SEGGER tries to update this database as often as possible. Still there are occasions, where support for a device is needed, that is not available yet. In such cases the Open Flashloader feature allows to add support to the J-Link. The device will be supported in similar fashion as all the devices supported already. This includes flash download as well as the unlimited flash breakpoint feature. In addition to creating support for the device, an existing CMSIS compatible flash algorithm can be used to create support for the J-Link as well.

For detailed instructions, please refer to our Wiki: https://wiki.segger.com/Open_Flashloader

The speed tests have been made with different debug probes and software under the same test conditions. SEGGER J-Link, IAR I-jet and ST-Link V2 and Keil's ULINKpro were tested. J-Link is the only probe which has been tested in different environments such as with IAR Embedded Workbench for ARM, KEIL uVision and SEGGER's J-Link commander. The tests with J-Link were performed with J-Link software version 4.59a and using J-Link flash loader.

All tests have been performed by placing a 512 KB program into the flash memory of a blank STM32F417IG microcontroller connected via SWD interface. The SWD speed has been selected at the maximum possible for each debug probe.

Tests via JTAG interface gave similar results. Project files are available upon request so to reproduce these tests results (support@segger.com).

This speed comparison shows the J-Link to be the fastest debug probe available. If you are considering the use of a device other than those found in this test, we urge you to ask the supplier for their flash programming numbers before making the move. We are confident SEGGER will outperform all others. With offerings to suite every debug/production need; SEGGER has you covered.

• Flash programmers
• Debug probes
• Trace probes

• Internal flash
• External parallel NOR flash
• Serial NOR flash ¹
• NAND flash ¹
• Data-Flash ¹
• EEPROM ¹

¹ Requires production programming software (J-Flash) and a so called custom RAMCode (since these flashes are not memory-mapped accessible)