Hot!How to write a bootloader

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naeem1234
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2018/05/24 06:43:43 (permalink)
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How to write a bootloader

Hi everyone

My MCU is PIC18F46K22 @20MHz Vdd=5V DIP40 pins package.

I want to learn how to write s basic bootloader for my MCU so that i can flash it from its uart port.

Can someone point me to relavent literature? Your help is highly appreciated.
#1

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    rodims
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    Re: How to write a bootloader 2018/05/24 06:59:18 (permalink)
    +1 (1)
    google is your friend, but you are not a friend of google ?
    http://www.microchip.com/forums/m951888.aspx
    and of course lots of other information in the forum.
    #2
    1and0
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    Re: How to write a bootloader 2018/05/24 08:28:09 (permalink)
    +1 (1)
    This is along the line of read the datasheet for me, search or google it for me, etc. :(
    #3
    katela
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    Re: How to write a bootloader 2018/05/24 14:29:22 (permalink)
    +2 (2)
    naeem1234
    Hi everyone

    My MCU is PIC18F46K22 @20MHz Vdd=5V DIP40 pins package.

    I want to learn how to write s basic bootloader for my MCU so that i can flash it from its uart port.

    Can someone point me to relavent literature? Your help is highly appreciated.

    If you search in Google "microchip application notes bootloader" there are plenty relevant literature, including this Bootloader Generator User's Guide

    Free online Microcontroller Tutorials and Projects for Hobbyists and students. From beginners to advanced. Website: www.studentcompanion.co.za
    YouTube Tutorials: https://www.youtube.com/user/StudentCompanionSA
    #4
    Aussie Susan
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    Re: How to write a bootloader 2018/05/24 19:31:15 (permalink)
    +2 (2)
    I always ask 'why do you think you need a bootloader' (let alone 'why do you think you can write a bootloader'!)?
    I my experience, a bootloader is of very limited use except when you have a final product that needs to be updated in the field by (possibly) untrained people.
    They are certainly not for beginners (and even people with a bit more experience than that in my opinion).
    Are you aware of the limitations that using a bootloader will entail?
    Susan
    #5
    NKurzman
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    Re: How to write a bootloader 2018/05/24 22:10:39 (permalink)
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    A bootloader is a common requested feature. It can be used to aid production or field updates. While the basic concept is easy the details can make it an advanced project.
    The microchip ez bootloader and MCC May make it easier for a PIC18.
    #6
    naeem1234
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    Re: How to write a bootloader 2018/07/10 12:07:53 (permalink)
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    Aussie Susan
    Are you aware of the limitations that using a bootloader will entail?

     
    No. I have no idea about that. Can you point out some of those limitations?
    Sorry for my very late catching up with my thread on the forum.
     
    #7
    naeem1234
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    Re: How to write a bootloader 2018/07/10 12:12:23 (permalink)
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    NKurzman
    The microchip ez bootloader and MCC May make it easier for a PIC18.


    I have never used MCC before. Is there any tutorial or help available for 'How to use MCC to generate Bootloader for PIC18F46K22'?
    Sorry for my very late catching up with my thread on the forum.
     
    #8
    mbrowning
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    Re: How to write a bootloader 2018/07/10 13:01:49 (permalink)
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    Is there any tutorial or help available for 'How to use MCC to generate Bootloader for PIC18F46K22'?
    How about reading post #4?

    Can't remember. I've slept since then - Mark
    #9
    jack@kksound
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    Re: How to write a bootloader 2018/07/10 13:15:53 (permalink)
    +1 (1)
    I think the arduino world has made the presence of a bootloader an expectation for many newer users, since most arduino mcu boards come with a preprogrammed bootloader and a usb interface.
    #10
    NKurzman
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    Re: How to write a bootloader 2018/07/10 13:42:34 (permalink)
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    jack@kksound
    I think the arduino world has made the presence of a bootloader an expectation for many newer users, since most arduino mcu boards come with a preprogrammed bootloader and a usb interface.


    It is not just Arduino. Every one wants Bootloaders.  Updates are difficult without them.
    #11
    NKurzman
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    Re: How to write a bootloader 2018/07/10 13:43:34 (permalink)
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    Go to the MCC Page, Look at it and the EZ Bootloader Page.  
    Then you will be able to ask questions.
     
    #12
    Danno
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    Re: How to write a bootloader 2018/07/10 14:35:51 (permalink)
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    Suggest the page here: https://www.microchip.com/promo/8-bit-bootloader
    And the bootloader user's guide linked at the bottom of that page.
    #13
    NKurzman
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    Re: How to write a bootloader 2018/07/10 15:37:30 (permalink)
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    Danno
    Suggest the page here: https://www.microchip.com/promo/8-bit-bootloader
    And the bootloader user's guide linked at the bottom of that page.


    So that is the current one?
    No EZ Bootloader / MCC Bootloader?
    #14
    Danno
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    Re: How to write a bootloader 2018/07/10 16:20:06 (permalink)
    +1 (1)
    That's the link to the 8 bit MCC bootloader. 
    EZ Bootloader only supports the 16 bit family.  
     
     
    #15
    NKurzman
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    Re: How to write a bootloader 2018/07/10 18:39:31 (permalink)
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    Danno
    That's the link to the 8 bit MCC bootloader. 
    EZ Bootloader only supports the 16 bit family.  
     
     


    Thank you for the Info.
    #16
    Aussie Susan
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    Re: How to write a bootloader 2018/07/10 19:56:49 (permalink)
    +3 (3)
    As for the limitations of a bootloader, some are:
    - you can't debug your application (unless the bootloader has this capability and they probably shouldn't)
    - they take up room: microcontrollers typically have just enough memory to perform the task required and adding a bootloader makes the FLASH requirements that much bigger; and if you try to share code between the bootloader and the main app then thighs can get really hairy
    - you can be left with an unusable program in FLASH: I know this is always a problem but typically you need twice the memory size of the app so you can always ensure access to a working version; perhaps not always important but a really good idea unless you want a cross customer
    - the bootloader code has to be absolutely rock solid: you must always be able to switch to the bootloader (internally via code and externally via a button etc) and have it work; this can be harder than you might think!
    Bootloaders have their place but (in my opinion) only for field/customer upgrades of software that has been thoroughly tested and debugged in a 'standard' development environment first. Adding a bootloader should be the last step in the development process, not one of the first (although it does need to be considered right at the start of the design effort).
    Susan
     
    #17
    qɥb
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    Re: How to write a bootloader 2018/07/10 20:32:17 (permalink)
    +4 (4)
    Aussie Susan
    ... if you try to share code between the bootloader and the main app then thighs can get really hairy

    ... and no-one wants that! ;)
     

    This forum is mis-configured so it only works correctly if you access it via https protocol.
    The Microchip website links to it using http protocol. Will they ever catch on?
    PicForum "it just works"
    #18
    naeem1234
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    Re: How to write a bootloader 2018/07/10 22:36:42 (permalink)
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    Aussie Susan
    As for the limitations of a bootloader, some are:
    - you can't debug your application (unless the bootloader has this capability and they probably shouldn't)
    - they take up room: microcontrollers typically have just enough memory to perform the task required and adding a bootloader makes the FLASH requirements that much bigger; and if you try to share code between the bootloader and the main app then thighs can get really hairy
    - you can be left with an unusable program in FLASH: I know this is always a problem but typically you need twice the memory size of the app so you can always ensure access to a working version; perhaps not always important but a really good idea unless you want a cross customer
    - the bootloader code has to be absolutely rock solid: you must always be able to switch to the bootloader (internally via code and externally via a button etc) and have it work; this can be harder than you might think!
    Bootloaders have their place but (in my opinion) only for field/customer upgrades of software that has been thoroughly tested and debugged in a 'standard' development environment first. Adding a bootloader should be the last step in the development process, not one of the first (although it does need to be considered right at the start of the design effort).
    Susan
     




    Thanks a lot.. thats very informative and helpful.
    #19
    BMD
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    Re: How to write a bootloader 2018/07/11 00:10:09 (permalink)
    +2 (2)
    Hi,
    I tend to agree with Susans view.
    You may want to consider what I did, I designed a small unit that performs the 'On the Go' function of PicKit3. It reads a thumbdrive for a hex file and programs it into a host device.
    Simple, without the limitations of a Bootloader.

    Regards

    Brandon
    #20
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