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'[PIC]: Bootloaders?'
2001\06\04@160113 by Jeff DeMaagd

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Bootloaders were discussed in a thread a couple weeks ago, as a way for a
PIC to program itself using a serial port in the circuit.  The guy operating
Bootload.com mentioned them but so far hasn't responded to a question I had.

I would like to be able to program using a bootloader board's serial port,
but I would like to use it as a general data communication port when not
programming the chip.

Is there such a bootloader and board available?  It would really help.

Thanks!

Jeff

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2001\06\04@162747 by Byron A Jeff

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On Mon, Jun 04, 2001 at 03:56:49PM -0400, Jeff DeMaagd wrote:
> Bootloaders were discussed in a thread a couple weeks ago, as a way for a
> PIC to program itself using a serial port in the circuit.  The guy operating
> Bootload.com mentioned them but so far hasn't responded to a question I had.
>
> I would like to be able to program using a bootloader board's serial port,
> but I would like to use it as a general data communication port when not
> programming the chip.
>
> Is there such a bootloader and board available?  It would really help.

It's not exactly what you're looking for, but take a look at Wouter's wloader:

http://www.xs4all.nl/~wf/wouter/pic/wloader

The reason that it's not exactly what you're looking for is because wloader
uses a separate I/O pin for the serial interface. This completely frees up
the UART for normal use.

In addition it's real simple to actually bit bang serial data out of the
wloader serial port. So you can get an extra serial debugging channel that's
separate from the normal UART.

The last thing is that there are serial loaders that are not Windows based
such as linwload for Linux:

http://www.ise.pw.edu.pl/~wzab/linwload/linwload.html

This allows me to program my PICs from my Linux box.

Hope this helps,

BAJ

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2001\06\04@175416 by victor Faria

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yes,Jeff
http://www.rentron.com
http://www.elproducts.com
one of these would do what you want.
and chuck or Bruce would answer any questions that you have.
hope this helps
victor
{Original Message removed}

2001\06\04@182536 by Brent Brown

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> I would like to be able to program using a bootloader board's
> serial port, but I would like to use it as a general data
> communication port when not programming the chip. Is there such a
> bootloader and board available?  It would really help.

Have a look at:
http://www.workingtex.com/htpic/PIC_bootloader.htm

Looks like a good product. I haven't tried it yet but I plan to in the
next few weeks. From what I've read so far I beleive the bootloader
remains active for 0.5sec after reset, to give you the option of
uploading new code, and after 0.5sec (or uploading complete) you
can use the serial port as normal.

Brent Brown
Electronic Design Solutions
16 English Street
Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile/text: 025 334 069
eMail:  brent.brownspamKILLspamclear.net.nz

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2001\06\04@190942 by Tony Nixon

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Jeff DeMaagd wrote:
>
> Bootloaders were discussed in a thread a couple weeks ago, as a way for a
> PIC to program itself using a serial port in the circuit.  The guy operating
> Bootload.com mentioned them but so far hasn't responded to a question I had.
>
> I would like to be able to program using a bootloader board's serial port,
> but I would like to use it as a general data communication port when not
> programming the chip.
>
> Is there such a bootloader and board available?  It would really help.
>
> Thanks!
>
> Jeff

http://www.bubblesoftonline.com/ROMzap.html

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Tony

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2001\06\04@210325 by shane

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Hi,

There is a bootloader at http://www.workingtex.com/htpic/PIC_bootloader.htm.

When I get around to recompiling it for Linux with Kylix, it'll be available for Linux too.

Cheers,
Shane.

> {Original Message removed}

2001\06\05@014637 by Vasile Surducan

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I'm interested only in homebrew or free bootloaders. These are:

http://www.picnpoke.com/demo/ROMzap.zip
www.htsoft.com/files/samples/bootldr.zip
http://www.execpc.com/~rfarmer/
http://www.xs4all.nl/~wf/wouter/pic/wloader
http://www.workingtex.com/htpic/PIC_bootloader.htm

I have tested only Rick Farmer's usart based and Wouter's one wire/any pin
bootloader. If you know other bootloaders please mail me.
Vasile


On Mon, 4 Jun 2001, Jeff DeMaagd wrote:

{Quote hidden}

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'[PIC]: Bootloaders?'
2001\07\25@092639 by James Burkart
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I've been messing with pics for a while. I have heard the term 'bootloader'
but am not familiar with what it is or the reason someone would need it in
the first place? Can anyone suggest any source of info that I may learn a
little more about these things?

Thanx...

James Burkart
RemoveMEjamesburkartTakeThisOuTspamyahoo.com

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2001\07\25@103750 by Robert E. Griffith

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Some PICS with Flash memory like the 16F877 can program themselves, without
the aid of programming hardware (low voltage programming).  A bootloader is
a small PIC program that resides at the top 256 bytes of program memory.
The reset vector points to it.  When the device resets the bootloader
executes and determines if there is new firmware waiting to be delivered on
a serial port or other comm channel. If it is, it downloads it into the rest
of the program memory. If not, it jumps to the normal program entry point.

A common configuration is to have a program on your PC platform that uses
the serial port to transfer a new program to a device over a serial port.

--BobG

{Original Message removed}

2001\07\25@103816 by uter van ooijen & floortje hanneman

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> I've been messing with pics for a while. I have heard the term
'bootloader'
> but am not familiar with what it is or the reason someone would need it in
> the first place? Can anyone suggest any source of info that I may learn a
> little more about these things?

Below: response by me on the Jallist to roughly the same question.
Wouter

> What is the difference between a programmer and a bootloader?

I will give you a (the?) long answer.

A programmer forces the target chip into programming mode, and can then
write all code, data and configuration info into the chip. The 'forcing' can
be done by applying ~14V to the MCLR pin (this is called HVP: High Voltage
Programming) or by applying a certain loical value to pin RB3 (or 4? check
the datasheets) during reset (this is called LVP: Low Voltage Programming).
A bootloader is a program running in the PIC itself that communicates with
your PC and writes to the code and data locations that are not occupied by
the bootloader. A bootloader can not change the configuration data in the
chip.

HVP is available on all PICs. Disadvantage: requires ~ 14V to enable
programming. Advantage: does not require dedicated pin(s).

LVP is available of the F87x and F62x chips. LVP can be enabled/disabled in
the configuration data. This data itself can only be changed using HVP.
Disadvantage: when LVP is enabled the LVP enable pin is dedicated to this
role, it is no longer available for general use. Advantage: does not require
anything power beyond the normal Vcc.

Using a bootloader is only possible when the chip can write its own
code/data memory, which is only supported on the F87x chips. Advantage:
communication can be intelligent, because the PIC is available to handle the
communication. Disadvantage: the chip must know whether to start in bootload
mode or to run the loaded program. This requires a pin, but this pin can
serve other purposes.

To further confuse things: Microchip requires that a "production" programmer
can verify (read back and check) the programming result at the extremes of
the power supply range of the intended target. When a 7805 is used in the
target this means reading at for instance 4.5 and 5.5 Volt. All other
programmers should be qualified as "prototype" programmers.

One more issue: The flash/eeprom PICs (16c84, f84, f62x f87x) require very
little current from the ~14V during HVP. The other PICs require substantial
current. This separates the 'low current' programmers that can only handle
the flash PICs from the 'high current' ones that can handle (nearly) all
PICs.

Last note: Some programmers require you to take the PIC out of its circuit,
put it in the programmer, program, and put the PIC back in the circuit. This
gets tedious after the 100th time, unless you never reach the 100th time
because one of the pins of the chip broke of at the 50th time. Hint: put the
PIC in a socket with round (stiff) pins and never take it out (that is: not
untill one of the sockets pins breaks) just plug and unplug this combo.
Other programmers connect directly to the PIC while it is in your target
circuit. This is called ICSP: In-Circuit Serial Programming. Never mind the
Serial (which has nothing to do with your serial port). It just means that
you can download and run your application without leaving your keyboard.
Note that some circuits that are not really ICSP-capable can do ICSP when
you remove the Xtal during programming.

After-last note: the F87x chips have build-in (hardware) support for
breakpoints, single stepping and other debugging goodies. The word is that
this eases development considerabley, but I have never used it (yet).

So what to choose after all this information? If you just want to start
experimenting with PICs I would suggest to buy a 16F877, build one of the
very simple serial-port HVP programmers that can be found piclist/techref
and load a bootloader in the PIC, and from then on forget the HVP programmer
(you could have build it on a solderless breadboard) and just use the
bootloader. When and F877 is not available I guess the F628 is not available
either, and the F84 is possible the only thing you can buy. Now you can
either buy one, build a HVP programmer and use it (I strongly suggest that
you select a programmer than can do ICSP), or buy two, build a simple HVP
programmer to program one for my WISP design and use the other as target.

When you want to do serious development work with PICs I suggest you buy a
PicStartPlus or another programmer that can be updated for new PICs. When
you want to do production programming (as opssosed to hobby work) select a
programmer (for your choosen target chip, or maybe for the whole PIC range)
that is advertised as "production" programmer.

Wouter

{Original Message removed}

2001\07\25@195131 by shane

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Hi,

A good example of a bootloader is at http://www.workingtex.com/htpic/PIC_bootloader.htm.

Cheers,
Shane.

> {Original Message removed}

2001\07\26@011927 by Vasile Surducan

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bootloaders:
http://www.bubblesoftonline.com/ROMzap.html
http://www.picnpoke.com/demo/ROMzap.zip
www.htsoft.com/files/samples/bootldr.zip
http://www.execpc.com/~rfarmer/
http://www.xs4all.nl/~wf/wouter/pic/wloader
www.workingtex.com/htpic/PIC_bootloader.htm
www.ise.pw.edu.pl/~wzab/linwload/linwload.html
http://www.seanet.com/~karllunt/picload.htm

Vasile

On Wed, 25 Jul 2001, James Burkart wrote:

{Quote hidden}

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2001\07\26@031720 by James Burkart

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BobG,

       Thanx... It makes sense to me now, I think I remember reading something in
the spec sheets for the '877 on Microchip's web site about this...

{Original Message removed}

2001\07\26@120734 by Olin Lathrop

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> Some PICS with Flash memory like the 16F877 can program themselves,
without
> the aid of programming hardware (low voltage programming).  A bootloader
is
> a small PIC program that resides at the top 256 bytes of program memory.

Minor nit, but a "bootloader" doesn't need to be exactly 256 locations long,
and doesn't need to be at the end of the memory.  One of mine, for example,
starts at the beginning of the last program memory page (1800h).

> The reset vector points to it.  When the device resets the bootloader
> executes and determines if there is new firmware waiting to be delivered
on
> a serial port or other comm channel. If it is, it downloads it into the
rest
> of the program memory. If not, it jumps to the normal program entry point.
>
> A common configuration is to have a program on your PC platform that uses
> the serial port to transfer a new program to a device over a serial port.

Aside from the minor nit, I agree with your description.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olinEraseMEspam.....embedinc.com, http://www.embedinc.com

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'[PIC]: Bootloaders?'
2011\06\25@115546 by John Ferrell
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I know there are many Google answers to this question but I
know that a current response on this list will provide a better
 response than I am likely to pursue from Google.


I would like to add a bootloader to a project. I would like
to keep this task as simple as possible. I am using a PIC 18F4520.
Is the method at http://www.microchipc.com/PIC18bootload/

As good as any or is there a less complicated or otherwise better approach?


A little tinkering with an AVR Butterfly has impressed me with the usefulness of a bootloader.
Some AVR chips come from the factory with the bootloader installed.

--
*John Ferrell W8CCW*

**

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*George Santayana*

**

2011\06\25@150036 by Vicent Colomar Prats

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There are many diferent bootloaders for pic 18F. All them work the same way,
first time you burn it into flash via programmer, and then go with a serial
communication(ex: usb to serial converter).

In microchip link, it can sound complicated, but it is not. When you have
first programmed then is exactly as easy and simple as any other micro via
bootloader thru a serial port.

2011/6/25 John Ferrell <EraseMEjferrell13spamtriad.rr.com>

{Quote hidden}

>

2011\06\25@151249 by jerry james

picon face
Check out AN1310.
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en546974

On Sat, Jun 25, 2011 at 12:00 PM, Vicent Colomar Prats <
RemoveMEvicentecolomarEraseMEspamEraseMEgmail.com> wrote:

{Quote hidden}

> > --

2011\06\27@093150 by John Ferrell

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On 6/25/2011 3:00 PM, Vicent Colomar Prats wrote:
{Quote hidden}

>> -

2011\06\27@094049 by John Ferrell

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On 6/25/2011 3:12 PM, jerry james wrote:
> Check out AN1310.
> www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en546974
AN1310 seems to imply that a programmer must be able to select a "bootloader mode". My programmers do not have that option.
I will start checking out some of the non-MicroChip solutions from Google searches.
I am getting anxious to get back to project so this bootloader thing may need to go back to the dormant project box!

--
*John Ferrell W8CCW*

**

*'A man's feet should be planted in his country, but his eyes should survey the world. '*

*George Santayana*

**

2011\06\27@103447 by Byron Jeff

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Consider using Wouter's ZPL (Zero Pin Loader) project. You can download it here:

http://www.circuitcellar.com/flash2002/Honorable/M285.zip

ZPL is a bootloader specifically designed to have a minimal external
footprint. It operates by wiggling the MCRL line of the part via a serial
port, which sends precisely timed runtime pulses whose length are measured
by the bootloader code. So you can embed it into an existing project with
little more than a transistor to wiggle MCLR. And this was specifically
designed for the 18F family. Comes with a python based loader, circuit, and
report describing the entire process.

The problem with the Microchip loader, the Tiny bootloader, and others is
that virtually all of them tie up the hardware serial port making it a
challenge to use when you have a project that also needs that serial port.
I have always preferred a loader with some form of bit banged serial
communications such as Wouters Wloader, ZPL, and Frank Sergeant's Pikme
because you can use any general purpose I/O pin instead of a specific pin
interface. MCLR can be used as an input only input in virtually any modern
PIC and it's almost always an out of the way pin. For example I'm working
with 16F1938's at the moment and MCLR is shared with PORTE3, which is the
only PORTE pin on the 28 pin part. Virtually useless for anything else, but
a great dedicated pin for a bootloader.

My current bootloader project is adding auto selecting bit rate code and
reliability when using the internal oscillators. I find that the clock
drifts due to temp changes enough that a consistent async connection is
difficult to pull off with out an external cyrstal or resonator. My plan is
to embed the clock signal and two bits of data into every async character
sent. So even if the clock drifts, it'll autoadjust with each character
sent.

BAJ

On Mon, Jun 27, 2011 at 09:31:08AM -0400, John Ferrell wrote:
{Quote hidden}

2011\06\27@103612 by Gordon Williams

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I use the Tiny Boot Loader.
http://www.etc.ugal.ro/cchiculita/software/picbootloader.htm

If your device is not one of the ones listed, it is quite easy to make the
changes required to make it work.

Regards,

Gordon Williams


{Original Message removed}

2011\06\27@104935 by Michael Rigby-Jones

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> -----Original Message-----
> From: RemoveMEpiclist-bouncesKILLspamspammit.edu [piclist-bouncesSTOPspamspamspam_OUTmit.edu] On
Behalf
> Of John Ferrell
> Sent: 27 June 2011 14:40
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC]: Bootloaders?
>
> On 6/25/2011 3:12 PM, jerry james wrote:
> > Check out AN1310.
> >
>
www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1
82
> 4&appnote=en546974
> AN1310 seems to imply that a programmer must be able to select a
> "bootloader mode". My programmers do not have that option.
> I will start checking out some of the non-MicroChip solutions from
> Google searches.
> I am getting anxious to get back to project so this bootloader thing
may
> need to go back to the dormant project box!

There is no "bootloader" mode required by a programmere, you simply need
a standard programmer (e.g. ICD, Pickit etc) in order to burn the
bootloader code to the micro, and then you need some method of sending
data to your bootloader (often some kind of serial protocol over RS232,
but could be I2C, CAN etc. depending on your application.)

Mike

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2011\06\27@110853 by Gordon Williams

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----- Original Message ----- From: "Byron Jeff" <spamBeGonebyronjeffSTOPspamspamEraseMEmail.clayton.edu>
> The problem with the Microchip loader, the Tiny bootloader, and others is
> that virtually all of them tie up the hardware serial port making it a
> challenge to use when you have a project that also needs that serial port..


Tiny bootloader doesn't tie up the serial port.  You can use the serial port
for whatever you want.

The boot loader runs on PIC startup a very short time to see if there is
anything to be downloaded.  If it doesn't detect any download it runs the
main program were you configure the uart and start using it.

Gordon Williams

2011\06\27@111211 by Dave Tweed

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John Ferrell wrote:
> On 6/25/2011 3:12 PM, jerry james wrote:
> > Check out AN1310.
> > www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en546974
>
> AN1310 seems to imply that a programmer must be able to select a
> "bootloader mode". My programmers do not have that option.

I haven't seen AN1310, but it sounds like it may be somewhat confusing.

The key concept is that you use a programmer OR a bootloader, not both at the
same time. You use the programmer to put the bootloader on the target chip,
and then use the bootloader to put the application code on it. Sometimes it's
possible to arrange things so that the bootloader and the initial copy of the
application get put onto the chip by the programmer in one go -- that's what
I did with my custom SPI-based bootloader for a deeply-embedded power supply
controller. It can get a bit tricky to make sure that the bootloader and the
application remain as two completely separate projects that can be built
independently, sharing data (if necessary) only in well-specified ways.

The other key concept is switching between the application and the bootloader
once the chip is installed in its application (this may be what AN1310 was
actually talking about). Sometimes this is handled by having the bootloader
briefly take control on every hardware reset and look for some indication
that it should NOT run the application; other times, the application gets
control following reset, but has a "hook" that it can jump to in order to
invoke the bootloader on command. Again, in my custom bootloader, we took the
latter approach, because it was important for the application code to get the
power supply controls into known states ASAP following power-up.

-- Dave Twee

2011\06\27@124230 by PICdude

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I've looked into bootloaders in the past primarily to be able to  program with less pins.  However, the usual TX/RX pins are in use for  something else in my app, so they haven't been a good option.   One-wire would be really nice for this, but the PIC would have to be  the master, and the code storage device (since I don't want to call it  a programmer here) would have to be the slave. Anyone ever seen one of  these?

Cheers,
-Neil.


Quoting Michael Rigby-Jones <KILLspamMichael.Rigby-JonesspamBeGonespamoclaro.com>:

> There is no "bootloader" mode required by a programmere, you simply need
> a standard programmer (e.g. ICD, Pickit etc) in order to burn the
> bootloader code to the micro, and then you need some method of sending
> data to your bootloader (often some kind of serial protocol over RS232,
> but could be I2C, CAN etc. depending on your application.)
>
> Mike


2011\06\27@134240 by Byron Jeff

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On Mon, Jun 27, 2011 at 12:08:28PM -0400, Gordon Williams wrote:
>
> ----- Original Message -----
> From: "Byron Jeff" <EraseMEbyronjeffspamEraseMEmail.clayton.edu>
> > The problem with the Microchip loader, the Tiny bootloader, and others is
> > that virtually all of them tie up the hardware serial port making it a
> > challenge to use when you have a project that also needs that serial port.
>
>
> Tiny bootloader doesn't tie up the serial port.  You can use the serial port
> for whatever you want.

Of course it does. Take a look at the hardware section here:

http://www.etc.ugal.ro/cchiculita/software/tinybldusage.htm

Specifically:

--------------------------------
On your board, you must have the PIC (pins TX,RX) connected to the serial
port of the PC (pins Rx,Tx), usually using a MAX232 level converter:
--------------------------------


>
> The boot loader runs on PIC startup a very short time to see if there is
> anything to be downloaded.  If it doesn't detect any download it runs the
> main program were you configure the uart and start using it.

Now of course the application can share the hardware serial port. But it
does require some management. For example if you wanted a MIDI or DMX
interface, then there would have to be some way to multiplex the TX/RX for the
bootloader with the TX/RX for the target equipment. Also there must be an
assurance that the target hardware doesn't somehow wiggle the RX line
during the boot phase.

This is exactly my point. A bit-banged serial interface can be a single pin
(input only or half duplex) that doesn't tie up any hardware I/O devices
for the target. The price is that the pin must be dedicated to the
bootloader task, at least at boot. But since any digital input pin can be
used, it gives a lot of flexibility for its use.  Another issue is that
since the hardware async serial interface is specifically used, there is
little opportunity to change the line protocol to give more flexibility
(autobauding) or reliability (encoding the clock signal into the protocol).
Which means most likely that even if there is an internal oscillator block
available, that an external crystal or resonator will still need to be
used. This ties up two more potential I/O lines that are multiplexed with
the crystal circuit pins.

Take a read of Wouter's ZPL paper. It outlines that I/O and hardware are
the most precious resources and should be allocated judiciously. A 28 pin
part may have 32K of flash and 4K of RAM. But it only has 25.5 I/O pins
max. Conservation of those resources is paramount with a bootloader.

BAJ


>
> Gordon Williams
>
> -

2011\06\27@140702 by Byron Jeff

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On Mon, Jun 27, 2011 at 12:42:16PM -0400, PICdude wrote:
> I've looked into bootloaders in the past primarily to be able to  
> program with less pins.  However, the usual TX/RX pins are in use for  
> something else in my app, so they haven't been a good option.  
> One-wire would be really nice for this, but the PIC would have to be  
> the master, and the code storage device (since I don't want to call it  
> a programmer here) would have to be the slave. Anyone ever seen one of  
> these?

That's an interesting idea. Seems to me that the CSD would still need to be
an active component acting as a server and a protocol converter. At first
glance the right part for the job sould be something like a PIC 12F1822.
It's 8 pins, has a full MSSP so it can do I2C and SPI along with a full
hardware EUSART. And it can be configured so that both pieces of hardware
can run at the same time. So something like this:

1. 12F1822 with half duplex one pin serial interface to the target.
Could be a simple as a wire OR config using diodes along with a pullup akin
to the I2C interface.

2. sdcard interface connected to MSSP running in SPI mode.

The target initiates by syncing with the CSD to establish the data
transmission rate and existance of the CSD. The CSD responds with available
load options (or none of no card is plugged in.). The target chooses the
firmware to be loaded which the CSD provides.

Just a quick thought on the process.

BAJ


{Quote hidden}

> -

2011\06\28@083014 by John Ferrell

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On 6/25/2011 3:00 PM, Vicent Colomar Prats wrote:
> There are many diferent bootloaders for pic 18F. All them work the same way,
> first time you burn it into flash via programmer, and then go with a serial
> communication(ex: usb to serial converter).
>
> In microchip link, it can sound complicated, but it is not. When you have
> first programmed then is exactly as easy and simple as any other micro via
> bootloader thru a serial port.
Thanks to all. I have not left the project. It will take me a little time to digest the suggestions.


--
*John Ferrell W8CCW*

**

*'A man's feet should be planted in his country, but his eyes should survey the world. '*

*George Santayana*

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