How to edit the value of the FOPT register?

[laszlomonda]

Hi guys,

I'd like to edit the value of the FOPT register of the KL03. According to my knowledge, the startup_MKL03Z4.S needs to be edited, but I'm quite clueless regarding the exact byte to edit. Which line / byte should I edit? Also, do I have to negate the bits of the desired value when writing into this file?

Thanks in Advance!

- Laci

[danieltruong]

Hi Kerry,

I'm in the same situation where I wish to change the boot option via FOPT flash address 0x40D.

Currently in the start-up file, the 0x40D location has value 0x3F (which means boot from flash). I want to change it to 0xFF (boot from ROM). The reason for this change is I want the bootloader in ROM to perform firmware upgrade with the host when such case is needed. 

After updating the start-up file as mentioned above, compiling and downloading the application into my board, the code got stuck in a small loop in the start-up file as follows (line 191, 192) and never got out of it.

Do you know why ? I'm using KDS 3.2.0 and J-Link debugger in my development.

Your help would be greatly appreciated.

--Daniel Truong

[kerryzhou]

Hello Daniel Truong,

   After you download it, your code will enter in ROM.

   So, please exit the debug mode, then use the KBOOT2.0 tool kinetisflash tool to download your application code.

   Please try to download your application code at first.

   If you still have question, please create the your own question post and write assign to kerry zhou,  then tell me the link, I will reply you directly in your own post.

Have a great day,
Kerry

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[danieltruong]

Kerry,

I followed your advice and it worked!

Thanks,

Daniel

[kerryzhou]

Hello Daniel,

    That's good!

     If you have the new question in the future, welcome to create the new question post.

Best Regards,

Kerry

[kerryzhou · Accepted solution]

Hi Laci,

    From the KL03 reference manual, you can get that the FOPT flash address is 0x40D:

  So you just need to modify the 0x40d in the startup_MKL03Z4.s.

/* Flash Configuration */
    .section .FlashConfig, "a"
    .long 0xFFFFFFFF  /* address 0x400- 0x403 */
    .long 0xFFFFFFFF  /* address 0x404- 0x407 */
    .long 0xFFFFFFFF  /* address 0x408- 0x40b */
    .long 0xFFFF3DFE /* address 0x40c- 0x40f */ //0x3d is the address 40d, if you want to change it, just change it to the data which you want.

    .text
    .thumb

About FOPT register each bit meaning, please refer to the following table:

Wish it helps you!

Have a great day,
Kerry

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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[laszlomonda]

Thank you very much, Kerry! Works perfectly!