Need IAP MCU

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I'm looking for a MCU with something like:

- 8bit (ie, simple)
- internal flash, 8k, IAP
- VCC 3V3
- free dev tools
- low pin count
- low power consumption

what families should I consider?

Basically, my question is: which MCUs can do IAP?

Thanks



Re: Need IAP MCU
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What is IAP?  Do you mean something like in-system programming?  If
that's the case, then I can't think of any flash-based microcontrollers
that /don't/ support in-system programming.

Based on the rest of your requirements, I'd go for an AVR.



Re: Need IAP MCU
On Tue, 02 Nov 2010 15:25:34 +0100, David Brown

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Always risky to guess requirements, but he may be looking for one that
can reprogram itself during execution. The NXP LPC ARM7s (and others,
I'm sure) do this by executing out of RAM while diddling with the flash
sectors. I've never had the need to do this but the process is outlined
in the applicable User Manuals. Basically write your handler into a
section of RAM, define the necessary function pointer, and call through
that function with particular parameters.

--
Rich Webb     Norfolk, VA

Re: Need IAP MCU

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Yep.


Or, flash routines can be stored in a separate, internal (boot)-ROM.



Re: Need IAP MCU
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Do you mean external?  How big is your total ROM space?

Re: Need IAP MCU
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The Renesas chips R16C/R32C can program the flash while running from
RAM (which is hardly a restriction.) In my interactive Forth
development environment (see my site below) I use that to store a
turnkey system in flash, that is detected and executed with the next
reset. Flash can be erased as well.

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--
--
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
We've slightly trimmed the long signature. Click to see the full one.
Re: Need IAP MCU

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case, then I can't think of any flash-based
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IAP - in application programming. You can program the flash while
your code is executing in the final product. Can AVR do that?



Re: Need IAP MCU
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Yes, but you might need to run in bootloading mode.  Basically, you
write your own bootloader.

Re: Need IAP MCU
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the case, then I can't think of any flash-based
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The answer is ... it depends on what you really want to do.

It is very unusual to want to update application code while the
application is running.  It is certainly /possible/ to do that, but it
is much harder to do properly (no matter what chip you use).

The usual way to handle IAP (to use your term) is to split the code into
two parts - a bootloader/updater, and the main application.  The
bootloader is kept simple - it should be able to communicate in some way
so that it can receive program updates, it should have minimal control
of the system (such as making an LED blink and keeping the outputs in a
fail-safe setting), and it should be able to verify and start the main
program.  The main program is what does the normal work.

So when you want to update the program, you put the system into bootmode
or update mode, the bootloader reads in the new program, burns it to
flash, and starts it up.

Lots of microcontrollers, including the AVR, support this model for
updating.  Typically the flash is split into two parts - a small boot
section, and a main section, with the ability to read and run code from
the boot section while erasing or programming the main section.



If you want to download a new version of the main application program
while the older version is still running, it's a lot more effort.  You
still need a boot program that will be your safety net - it starts on
bootup, and verifies that the main program is good to go, and can handle
an update if needed (such as if there is a power failure during the main
update - always take into account that the update can fail).  You then
need to be able to run one copy of the main application while
downloading and burning the new version.

This almost certainly means external memory of some sort, unless your
programs are so small that they can run entirely from internal ram, and
it pretty much rules out the AVR.

Once the new program is burned, you re-boot into the new program.


If you want to update the application without doing any sort of reboot,
you've got an even bigger challenge.  It is possible (look up ksplice
for an example), but there are almost certainly better ways to handle
your project.


In short, use an AVR with a bootloader.  It will be the smallest,
cheapest and easiest solution.

Re: Need IAP MCU

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define "free"

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define "low"

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Freescale 9S08, one pin for BDM access.

You might want to spend money for tools. I use a P&E BDM interface
with NoICE and the Cosmic compiler (the latter should exist in a free
limited version). There are free BDM circuits around working with
CodeWarrior.

Oliver
--
Oliver Betz, Munich
despammed.com is broken, use Reply-To:

Re: Need IAP MCU
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I need only 3 I/O pins.
The MCU should be battery oriented.



Re: Need IAP MCU

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8K flash and low pin count are generally incompatible due to die size.
NXP Cortex M0 or M3, ATMega (If you can get them), PIC16 (most) /18F(all) will
all do the above,
although the free version of the PIC compiler is somewhat sucky.
 

Re: Need IAP MCU
2010-11-02 14:34, aleksa skrev:
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ATtiny25 has
8 kB Flash,
In Application Programming
3V3
AVR Studio + WinAVR is free of charge
8 pins
low power consumption.

If you need more pins, then there are bigger devices in the AVR family.
ATmega88PA would be one choice.

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Best Regards
Ulf Samuelsson

Re: Need IAP MCU

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That would be the Tiny85, the T25 has 2K

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Re: Need IAP MCU
2010-11-06 18:38, Mike Harrison skrev:
wrote:
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Yes, Usually I recommend people to read what I mean,
and not what I write, and this is certainly true in this case...

BR
Ulf


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