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Hot!dsPIC33EV CodeGuard doubt

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VB_VB
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2021/01/16 09:52:46 (permalink)
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dsPIC33EV CodeGuard doubt

Hello everyone, 
I think that the document about CodeGuard that you can find here
https://ww1.microchip.com/downloads/en/DeviceDoc/70005182a.pdf
about the dsPIC33 family is not always 100% clear. 
At page 9, there's the detailed description of the segments access rules.
In particular, at page 9 table 4-2 describes BS and GS access rules. 
However the first row of the table consider the Segment Security Level. 
Here's my question: Segment Security Level of the BS or of the GS ?

Let's image I set BS security to HIGH and GS security to NONE. 
Which column do I have to look in the table ?

It looks like they have merged the rules for BS and GS into one table, 
but doing that way makes rules not clear ?
How to really read that table ? 
 
#1

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    JPortici
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    Re: dsPIC33EV CodeGuard doubt 2021/01/16 13:05:00 (permalink)
    +1 (1)
    Unless write protect is active, BS can be read and written from BS.
    BSS can read/write GS.
    GS can be read and written from GS, GS can NOT read or write BS.
     
    So what's the different between standard and high?
    If i'm right, with security = NONE you can read program memory with ICSP.
    With security = STANDARD you can't read program memory from ICSP but you can read it from within the code
    with security = HIGH BS can read/write everything and GS can only read/write itself.
    #2
    VB_VB
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    Re: dsPIC33EV CodeGuard doubt 2021/01/16 23:52:42 (permalink)
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    Thank you JPortici for your answer.
    I think the following table resumes the table 4-2 in a much more terse and understandable way. Could you check if the table looks correct ?
    Target is the memory segment which we try to read/write/erase.
    The table states the highest security level that makes the operation possible. 
    E.g. is the highest security level is 2 (standard), then the operation is possible only 
    with None and Standard, but not with High.
    Anyone can feel free to comment, correct, ecc...



    GS security level
    1: None
    2: Standard
    3: High
     CODE EXECUTES FROM
     BS GS

    BS 3 1
    TARGET
    GS 2 3

    Write and Erase are never allowed if the corresponding write protection is ON.

    post edited by VB_VB - 2021/01/17 00:04:17
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    VB_VB
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    Re: dsPIC33EV CodeGuard doubt 2021/01/17 00:01:52 (permalink)
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    I'm sorry for the formatting of the previous post. 
    I tried to find a way to write posts and just make the post appear as if you see it on a simple editor. 
    Sometimes people are excellent in making things more complicated than they are.
    We don't need fancy emoticons and colors here, just a plain text editor.

    Can I just write a message and have WYSIWYG ?
    WYSIWYG : What You See Is What You Get 
    #4
    VB_VB
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    Re: dsPIC33EV CodeGuard doubt 2021/01/17 00:30:36 (permalink)
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    deleted
    post edited by VB_VB - 2021/01/17 01:17:45
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    VB_VB
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    Re: dsPIC33EV CodeGuard doubt 2021/01/17 01:17:16 (permalink)
    -1 (1)
    Hello again, please open the attached documents where everything is formatted and explained much better.
    It's a .doc file so you should open it with Google docs if you haven't M$ Word.

    Feel free to modify and re-upload the documents, so maybe Microchip will make that CodeGuard document easier to understand.
    post edited by VB_VB - 2021/01/17 01:28:08
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    VB_VB
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    Re: dsPIC33EV CodeGuard doubt 2021/01/17 02:24:18 (permalink)
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    More development and some example code. 
    I guess that everyone which is active in developing a Bootloader is interested in this 3d.
    Again, please read the attached doc file.

    Now you will excuse me, but it's Sunday morning and banging my head on some obscure uCHIP table is not the best...
    #7
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