Bootloader

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Hi all,
I am new to Embedded design industry.
I have some questions regarding C and bootloader.
1. What is the use of pointers, function pointers, structures, structure
pointer, array of structures, array of pointers, unions with respect to
embedded programming?

2. Why we need bootloader? What is the use of bootloader although we ve
debuggers for programming?

3. Why PBL and SBL?? Why not a single memory?

        
                    
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Re: Bootloader
On 04/02/14 18:19, prashanthgr.1992 wrote:
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It is all explained here...

http://bit.ly/1fELd5R

Re: Bootloader

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They are used the same way they are in non-embedded programming.

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Maybe you don't.  Some platforms use them, some don't. Whether you
need one or not depends on your hardware and software architecture.
Small embedded systems often don't have a bootloader.

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A bootloader initailizes the hardware and then loads/starts a second,
larger application.

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No clue what you mean by that.

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Don't know what you mean by that either.

--  
Grant Edwards               grant.b.edwards        Yow! Catsup and Mustard all
                                  at               over the place!  It's the
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Re: Bootloader
Grant Edwards schreef op 04-Feb-14 7:36 PM:
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You interpret the term 'bootloader' as a minimal piece of software that  
always gets control at startup, and is responsible for the loading of  
the 'real' application.

There is another interpretation, mainly for small microcontrollers with  
flash memeory. In this case the bootloader is a small piece of software  
that CAN be run at startup to load new content for the flash over some  
communication link, after which the chip can be reset another time, this  
time enabling the (new) application in flash.

This second form of bootloader is very common on small micronctrollers,  
for instance all LPC ARM/Cortex UC's I know have a built-in serial  
bootloader, and some have an additional bootload option over CAN or USB.

For this interpretation, an answer could be 'to facilitate in-field  
software updates'.

Wouter


Re: Bootloader
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Given the context from the other questions, my _guess_ would be the
OP means Primary Boot Loader and Secondary Boot Loader.

My _guess_ would be the PBL is the on-chip boot ROM and the SBL is
something like the U-Boot SPL loader.

Simon.

--  
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world

Re: Bootloader
On Tue, 04 Feb 2014 12:19:29 -0600, prashanthgr.1992 wrote:

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Mostly the same as desktop programming, although on a small embedded  
application your usage of all that is heavily shaped by the fact that you  
don't have a lot of memory or processor time to waste.

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You don't _need_ a bootloader, per se.  Often if you've got some really  
big software load (like linux with applications, or VxWorks, etc.) a  
bootloader makes your life easy.

A shippable product does not have a debugger attached to it, any more  
than your average 18 year old kid still has an umbilical cord.

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Presumably you are asking a question about a specific processor or  
board.  This may sound odd, but not everyone here has used everything  
available.  Perhaps this has to do with people having finite lifetimes.

I suggest you either tell us more about what PBL and SBL are, or that you  
study the documentation for the product in which you've found those terms  
and see if you can figure it out for yourself.

--  

Tim Wescott
Wescott Design Services
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Re: Bootloader
On 04/02/14 19:51, Tim Wescott wrote:
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I made a shipping product with a debugger still attached.  I used an  
FTDI 2232C chip with one channel connected to the microcontroller's UART  
(for normal PC to board communication while running), and the other as a  
JTAG-style connection (BDM, to be accurate) to the microcontroller.  
While it didn't support full debugging, it supported "programming over  
the debugger" from the PC for downloading and updating the software.  It  
worked very well, and is a method I could well use again - especially  
for ARM chips with OpenOCD running on the PC side.



Re: Bootloader
David Brown wrote:
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Do you mean "shipped" as in "run at a test site" or "as production"?
Having an end customer run a debugger at boot time*, or
even at update time seems troublesome.

*not that you said you did that; it's a bit ambiguous.

Even on stuff with 68000 or Codlfire-in-68000, long as there's FLASH  
memory for program storage, I've mainly seen people write program  
loaders over a 232 port for going on 25 years now.

Even better; have a filesystem in FLASH.

--  
Les Cargill


Re: Bootloader
On 04/02/14 19:19, prashanthgr.1992 wrote:
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When you have homework questions, be honest about them.  You are a  
/long/ way from being in any industry as yet.



Re: Bootloader
prashanthgr.1992 wrote:
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Get out while you can.

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Yes!

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You don't need it since you use debugger.

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Some memory is more equal than other.

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--
Les Cargill

Re: Bootloader

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Vladimir, come back, we need you...

--  

John Devereux

Re: Bootloader
John Devereux wrote:
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Very much so :)

--  
Les Cargill


Re: Bootloader
prashanthgr.1992, you need help on the ground.

The non-snark version:

prashanthgr.1992 wrote:
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Those are just elements of 'C' programming and not constrained to embedded.

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Supposedly, you really cannot ship a product with a debugger attached.
A boot loader "loads" a program at "boot" time. Examples might be
LILO or U-Boot.

your question as asked leads to a lot of questions.
http://stackoverflow.com/questions/15696258/what-is-bootloader-and-startup-code-in-the-embedded-systems

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Beats me. Sounds specific to an architecture.

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--  
Les Cargill


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