J-Link Pro Flash Download: Compare very slow

    • J-Link Pro Flash Download: Compare very slow

      Hi,
      i'm using j-link pro, either with USB or Ethernet connection.
      SEGGER J-Link ARM Pro V5.0
      J-Link Pro V5 compiled Feb 4 2025 09:50:59
      Debugger: STM32U599ZJ


      The compare before flash mode is very slow.

      Evgery method (CRC, Read back, fastest method) is same slow.

      Compare needs same time as flashing itself.

      So i have to disable compare, disable L1 verify, skip L2-Verfiy to have acceptable speed.
      But this should be not the intention.

      Why is the comparing with CRC so slow? i assume, that this method just has to send a few crc and small programm to target, but not all the flash content.
      My project has ~ 2MB flash, so comparing needs ~ 25 seconds !!

      Same behaviour on linux / windows, usb / ethernet.
      What to do?
      Thanks.

    • Hello,

      The limiting factor here is the speed of the target MCU.
      Since the target needs to calculate the CRC over the entire 2MB flash, this process naturally takes some time.

      Best regards,
      Simon
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    • Hello Simon,
      thank you for your answer.

      The target MCU runs with 160MHz. I really don't think, that calculating the CRC needs 25 seconds. Maybe the CRC-algorithm is programmed in BASIC and runs on C64 ;)

      It looks like, that in any strategy the full content is transfered to the target MCU und a byte-by-byte compare is done.
      Therefor it needs as long as reprogramming the flash (which transfers the content to the MCU, too, and flashing itself doesn't need really any time (nowadays))

      Any further ideas?
      Thank you.