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Microchip PICs don't come pre-installed with a bootloader firmware??

Discussion in 'Embedded' started by johannblake, Dec 22, 2005.

  1. johannblake

    johannblake Guest

    I am just learning about Microchips's bootloader capabilites. What is
    not clear from any of the documentation I've read is whether the chips
    with bootloading capabilities ship with the bootloader firmware
    installed. Some posts in this group indicate that you have to add the
    firmware yourself with an ICSP, which of course requires a hardware
    programmer and the corresponding software.

    This may sound like a dumb question, but if that is true, why?? Why
    wouldn't Microchip just burn the chips with the bootloader so that all
    of us poor developers only need to connect the chip to a serial port
    and do an instant download of our application code without requiring a
    hardware programmer. Am I missing something here?

    One additional note. I read in Microchip's AN581 doc that they supply a
    program called Quick Programmer used to program / communicate with a
    bootloader. I couldn't find such a product on their web site. Has this
    been integrated into their MPLAB?

    Thanks for your response
    Johann Blake
     
    johannblake, Dec 22, 2005
    #1
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  2. The point you miss is that some don't want a bootloader because it eats
    memory. Also when Microchip installs a bootloader, does it meet your
    requirements? Maybe you want a simple bootloader to load your programs, but
    I would want a more secure bootloader with encryption so that people who get
    my images to load, cannot disassemble those images and "steal" my design. So
    in short: the requirements for a bootloader can be very different for anyone
    and it would be therefore pointless to preload a bootloader.

    Meindert
     
    Meindert Sprang, Dec 22, 2005
    #2
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  3. johannblake

    Andrew M Guest

    It's fair to say that most of the PIC business is either factory programmed or
    in-circuit programmed in high quantities. There is no reason to instal a bootloader
    for either of these situations. These guys sell a billion PICs a year, folks...


    I know of companies who program their own bootloaders into PICs but they are for
    specific communications or security requirements.

    -Andrew M
     
    Andrew M, Dec 22, 2005
    #3
  4. johannblake

    johannblake Guest

    Thanks for insight. I wasn't aware that the bootloader was using the
    same memory space that my app would use. Too bad that Microchip doesn't
    just include a built-in bootloader separate from the memory space used
    for applications. This could just be a basic bootloader to
    download/upload code or data. They could even allow you to set a
    password to avoid the problem that you mentioned.

    As I now see it, the point of the bootloader really is meant for after
    production purposes. It doesn't appear to be possible to avoid using a
    hardware programmer at this stage.

    Thanks again
    Johann
     
    johannblake, Dec 22, 2005
    #4

  5. They can't program it in the factory because everybody's application is different.
    Different IO setup requirements, different comms interfaces, speeds & protocols.

    It would be a waste to spend money putting code in the chip that is only usefult to a small
    proportion of users.
     
    Mike Harrison, Dec 22, 2005
    #5
  6. johannblake

    Thad Smith Guest

    I consider the JTAG download support a bootstrap loader. A lot of
    companies provide simple programmers based on this.

    The MSP430 has both a JTAG programming interface and a asynchronous
    serial bootloader. The async version resides in user space. I have
    used it because it requires few pins, but I believe it is a little slower.
     
    Thad Smith, Dec 22, 2005
    #6
  7. johannblake

    Ian Bell Guest


    better to use a decent micro like the 8052 variants from Philips. All come
    with a built in bootloader in ROM that does not eat into your program
    space.

    IAn
     
    Ian Bell, Dec 22, 2005
    #7
  8. All?
    The 87C52 I use doesn't have one....

    Meindert
     
    Meindert Sprang, Dec 22, 2005
    #8
  9. johannblake

    Stephen Guest

    I wish more microcontrollers would offer built-in ROM bootloaders.

    How many products have you ever used or owned that offered flash
    updating to the end user (motherboards, modems, satellite/freeview tv
    decoders, etc.) that said somewhere in the flash upgrade procedure
    instructions something to the effect of "interrupting this process may
    permanently damage the product".

    I interpret this to mean "we cost-cut the product so much that there is
    no ROM bootloader and if you get a power-cut, any form of serious
    glitch, crash, or any other type of failure, you might end up with a
    dead product that needs to be returned to the factory", which is often
    too expensive a repair option. It may only be a small risk, but I don't
    want to tell my customer 9000 miles away that the hex file I just sent
    him will work but that there is a small chance he'll have to send the
    equipment here instead. Protecting a bootloader in a flash boot block
    would help, but still isn't guaranteed. Adding an EPROM for this purpose
    alone is too expensive.

    By contrast, the last two major product developments I have done used
    microcontrollers with primitive ROM bootloaders. These allow me to
    absolutely guarantee a means by which the end user can recover from a
    faulty flash upgrade attempt regardless of what state the contents of
    flash are. If I require security or other features I can use the
    primitive bootloader to download a complex bootloader and continue from
    there to download the full firmware image.

    I may only end up using the primitive bootloader as a fail-safe if the
    regular upgrade process fails, but at least the option is there, and
    effectively "hard-wired" into the chip. The ROM only needs to be
    typically a few hundred bytes for a primitive bootloader and typically
    an I/O pin to activate it on bootup.
     
    Stephen, Dec 22, 2005
    #9

  10. There are several ways to communicate with a processor.
    Just that it has a UART doesn't mean this is the to be
    used communication channel. SPI, external UART, Ethernet
    come to my mind. Then when you already
    communicate with a processor, then you'd wish the
    bootloader to have the same protocol such that it fits
    into your application.

    Rene
     
    Rene Tschaggelar, Dec 22, 2005
    #10
  11. johannblake

    Scott Moore Guest

    Why don't you order it burned with a bootloader ? Most distributors
    have automated part programmers, and can deliver the chip with your
    bootloader on the part for little, or no price increase over the
    raw part.
     
    Scott Moore, Dec 22, 2005
    #11
  12. johannblake

    Ian Bell Guest

    Please read more carefully. I said all the Philips VARIANTS

    Ian
     
    Ian Bell, Dec 22, 2005
    #12
  13. Nah Ian, you'll have to do better than that :)
    The 8052 originates from Intel, so if you say "....8052 variants from
    Philips. All come.....", you don't say "some 8052 variants from Philips".
    This is standard math basics as taught on high-school. The way you said it,
    you implied that all variants from Philips have a bootloader. Damn, this is
    bad for my headache.....

    Meindert
     
    Meindert Sprang, Dec 23, 2005
    #13
  14. johannblake

    Ian Bell Guest

    Think again - I did not say all Philips 8052 devices have a boot ROM loader
    I said all Philips 8052 VARIANTS i.e. variants on the original 8052 from
    Intel and not the straight copies.

    Ian
     
    Ian Bell, Dec 23, 2005
    #14
  15. Ah, now I know what you mean. And I am still not convinced. The Philips
    80C451 has no bootloader and is not a direc copy of an existing Intel
    type..... :)=)

    Meindert
     
    Meindert Sprang, Dec 23, 2005
    #15
  16. johannblake

    Ian Bell Guest

    That part is discontinued. Try again.

    Ian
     
    Ian Bell, Dec 23, 2005
    #16
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