How to create custom init sequence?

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    • How to create custom init sequence?

      Hello,

      i try to create a procedure to unlock an MAC7116 chip using J-Flash. For this i need to boot the chip into extended mode where internal Flash and RAM are disabledm connect to the device, setup clocks and write some commands to the internal CFM controller. The chip does not provide a TRST signal for the TAP, instead the chips /RESET is used. One thing that i found out soon was, that the Segger default using 0 ms delay after init reset command is wrong. It can't connect to the chip because it needs a bit of time to recover from reset. Using 20 ms is just fine. Maybe this is because of the fact Segger doesn't suppose to use TRST as signal, but to reset TAP via JTAG procedure...

      For now, when i use "Reset type 0" like in the Segger selection default for this chip, i end up with an error that the RAMcode couldn't be downloaded ;)

      Now i wonder how to get around this?
      When does J-Flash try to download the RAMcode? Right after any init steps or after Reset?
      Is RAMcode always needed? Or does J-Flash support a legacy JTAG only way to communicate whith the chip?
    • Hello,

      Thank you for your inquiry.
      To make sure we understand you correctly here you are looking to unlock and reflash the internal Flash of a MAC7116 MCU.
      Correct?
      In that case no extra RAMCode would be needed as J-Link software provides the Flash loader for the internal Flash of that MCU already.
      The general sequence for J-Flash is reset, halt, erase, program, verify.
      Now between the halt and erase you can execute init steps in J-Flash in project settings in the "MCU" tab.
      Should this not be enough control you can use a JLinkScript file. For more information see J-Link user manual.

      Best regards,
      Nino
      Please read the forum rules before posting: Forum Rules

      Keep in mind, this is not a support forum. Its main purpose is user to user interaction.
      Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
      Should you be entitled to support contact us per e-mail.
      Alternatively our support system can be used as well: segger.com/ticket/
    • Thanks for fast reply and for pointing out how J-Flash works!
      Yes, i want to unlock and reflash the content of the MAC7116.
      As for the datasheets the MAC needs a special unlock procedure by sending special commands to the internal Flash controller (CFM) via JTAG. This is done by memory mapped registers. All could be done by writing to registers only, no need to have any RAMcode at place (i think). So i if i add all needed commands into the MCU Init sequence, it should all work, right? But what happens if they are done? Will the J-Flash software try to upload the RAMcode anyway, or is there some Init-Command to prevent this?

      And what do you mean by saying "J-Link software provides the Flash loader for the internal Flash of that MCU already." ? Does it mean that if i use J-Link commander it is possible to connect and issue some kind of "unlock" command which do all the work for me? :)

      THX
    • Hello,

      elektroll wrote:

      So i if i add all needed commands into the MCU Init sequence, it should all work, right? But what happens if they are done? Will the J-Flash software try to upload the RAMcode anyway, or is there some Init-Command to prevent this?
      That should work. The RAMCode will take care of Flashing the new image after unlocking the device. You just have to make sure the target device is in a ready state when trying to Flash it again.


      elektroll wrote:

      And what do you mean by saying "J-Link software provides the Flash loader for the internal Flash of that MCU already." ? Does it mean that if i use J-Link commander it is possible to connect and issue some kind of "unlock" command which do all the work for me?
      This means that no matter which tools you use that utilizes our J-Link library the Flashloader for the internal Flash of that target device is already in place.
      All you need to handle right now is the unlocking prior to the Flashing via the options I presented you in my last post.

      Best regards,
      Nino
      Please read the forum rules before posting: Forum Rules

      Keep in mind, this is not a support forum. Its main purpose is user to user interaction.
      Our engineers will try to answer your questions between their projects if possible but this can be delayed by longer periods of time.
      Should you be entitled to support contact us per e-mail.
      Alternatively our support system can be used as well: segger.com/ticket/