Atmel 89C51RD2 losing program

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I have designed a product using the 89C51RD2 processor. Significant
numbers of the product are losing the Flash program in some way,
apparently on power up, they work fine for a while then fail to run on
the next power up. Reprogramming the processor restores operation.

The program memory has to be locked, so I can't tell if the program is
being corrupted or if the boot vector is being changed. There is no
firmware update software (except the built in boot loader). Has anyone
else experienced this?
--
Tim Mitchell

Re: Atmel 89C51RD2 losing program
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To answer my own question, I have just visited the Atmel site and they
have recently added a note about this device losing/corrupting flash
memory on power up/down or in brownout. So I am obviously not the only
one...
--
Tim Mitchell

Re: Atmel 89C51RD2 losing program
On Mon, 21 Jul 2003 17:24:05 +0100, the renowned Tim Mitchell

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Are you using an external reset chip?

Best regards,
Spehro Pefhany
--
"it's the network..."                          "The Journey is the reward"
snipped-for-privacy@interlog.com             Info for manufacturers: http://www.trexon.com
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Re: Atmel 89C51RD2 losing program
Hi!
I have just made a design with the Atmel AT89C4051 microcontroller.
What kind of reset chip and schematic would you sujjest me?
I am afraid if the flsh memory could become corrupted after a bad reset or when
the
supply voltage
becomes under a certain range.
Any references chips that are currently used with Atmel Micro ma interest me .
@+
Regards,
MB.
--
http://matthieu.benoit.free.fr /



Grzegorz Zalot a écrit :

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Re: Atmel 89C51RD2 losing program
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when the
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 Unlike the RD2/ED2, the 89C4051 family cannot self pgm, and
needs 12V Vpp on RST - so you should be safe from corruption.

 -jg

Re: Atmel 89C51RD2 losing program
Hallo Matthieu Benoit !:
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The AT89C4051 have a brown-out !


--
Grzegorz Zalot

complex ltd.
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Re: Atmel 89C51RD2 losing program
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Jim, where is this latest info? All the information I can find, and our
Atmel disti, say that there is no DIP package available.
--
Tim Mitchell

Re: Atmel 89C51RD2 losing program
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 - on their web ?

http://www.atmel.com/dyn/resources/prod_documents/doc4235.pdf

 This is the june copy, that adds DIP40, and mention of the
voltage reset.
 Finding one may be a challenge, vendors often ramp-down the old
device faster than the supply pipeline ramps up the replacement :)

 Let us know how you go, the RD2 is a quite popular device, so
others will be making this migration.

 The on chip regulator is a nice feature :
less power and better EMC but '5V drop in' compliant.
 The wide Vcc means you stock one device to cover both 3V &
5V designs.

 - jg

Re: Atmel 89C51RD2 losing program
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Right... I was slightly put off by the fact that the main page for the
device (and the device parametric table, and in fact the whole of their
website) does not mention the dip40 package. Having to download a 2MB
PDF file to find out is a bit of a bummer.

Anyway some samples are now supposedly winging their way to me so we'll
see if it works OK.
--
Tim Mitchell

Re: Atmel 89C51RD2 losing program
On Tue, 22 Jul 2003 09:38:37 +0100, Tim Mitchell

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Why don't you use the SMD device together with the required reset chip
on an adaptor board ? The 44pin quad flat pack easlity fits on a PCB
the size of of DIP40.

Regards
   Anton Erasmus




Re: Atmel 89C51RD2 losing program
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Yes, it is a shame that Atmel have only just made this fact known after
producing the device for 3 years.
--
Tim Mitchell

Re: Atmel 89C51RD2 losing program
Hallo Tim Mitchell !:
.....
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Very quickly :-\ ...

I have problems from PIC16F648 now - sometimes the program is wrong executed. It
seems, the ram-banks ase wrong restored.

And ... good luck with T89C51RD2 ......
--
Grzegorz Zalot

complex ltd.
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Re: Atmel 89C51RD2 losing program
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 It's not that uncommon - any device that has the ABILITY to self
program
( ie via a SW call, and not with external Vpp's ) needs to be treated
with
care, to ensure erratic SW calls CANNOT occur, and brownout is a classic
instance.

 I would try and get samples of the AT89C51ED2, as that shows a Voltage
reset
(but the data does not mention the voltage threshold) - on some uC these
voltage resets still leave a no-mans-land where the XTAL is too fast for
the
Vcc.
 As the AT89C51ED2 also regulates the core with the same Vref, it should
(in theory :) be able to work very well in this respect.

- jg

Re: Atmel 89C51RD2 losing program
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in
design

I just started working with the AT89C51RD2 yesterday - the PLCC44 version
that I'm using in a DIP 40 socket via an Iguana Labs adapter. I noticed a
brownout section in the AT89C51RD2 documentation but it's devoid of it in
the T89C51RD2. Looks like Atmel found the oops and corrected it.

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The Atmel web site is never up to date regarding delivery or availability.
At least I've never found it to be, but yes, my distributor said the same
thing. We have about 800 of the T89C51RD2s fortunately. ;-) Too bad one
cannot get the AT89C51RD2 in DIP 40 form!

-->Neil



Re: Atmel 89C51RD2 losing program
Hallo Tim Mitchell !:
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You MUST have an external RESET with Brown-Out !!! Otherwise the Flash is
sometimes erased, in 64-byte sectors. I know this problem form 8 months .....

HTH ...

--
Grzegorz Zalot

complex ltd.
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Re: Atmel 89C51RD2 losing program
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The standard reset circuit is just  a capacitor to Vcc and perhaps a
resistor to pull down. Shouldn't be too hard to bodge an MCP101 reset
chip (TO92) in there somewhere, perhaps with a blob of epoxy to stop it
dropping off.

Paul Burke


Re: Atmel 89C51RD2 losing program
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But according to Temic/Atmel, it IS the standard circuit.

The C/R circuit has always been the standard reset circuit for all 89C5x
parts, and the current Temic/Atmel data sheet for the part (rev G) says:

An internal diffused resistor to Vss permits a power-on reset using only
an external capacitor to Vcc.

If you can't rely on the manufacturer's data sheet, where do you get
valid information from??
--
Tim Mitchell

Re: Atmel 89C51RD2 losing program
Hallo Tim Mitchell !:
..........
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Theoretically ..... but practically no.

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 From the colleagues, which know this provesor a litte better .....

This is not a normal situation, but a small RESET-circiut is better then lost of
program ....

--
Grzegorz Zalot

complex ltd.
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Re: Atmel 89C51RD2 losing program

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They may say so, and as far as generating a reset pulse on power-off, that
circuit does the job nicely, no problem.

The *real* problem with this approach is not power-on reset, though:
it's brown-outs, or bad power sources that ramp up slower than your RC
circuit charges up --- generally anything that can send your micro
into a situation plainly forbidden by its data sheets.  

The crucial issue was already named in another posting: a device that
can potentially rewrite its own (supposedly) non-volatile program
memory is in serious danger of doing that accidentally in such illegal
operating conditions.

And then there's Murphy's law, which says because this _can_ possibly
go wrong, this is exactly what _will_ happen, sooner than you'ld like
to.  Usually only at your customer's site, and only after you've
delivered enough of the units that replacing them will be somewhere
between a major hassle and a strict non-option.

So: replace your RC circuit by a proper CPU monitor IC, and you'll
have one issue less to lose sleep about.  Only go without one if your
micro already has internal Vcc watchdog circuitry (but make you you
can trust that --- test it!).
--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

Re: Atmel 89C51RD2 losing program

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The point I was making is that it ought to be easy to bodge on an active
level detecting reset chip. The result might look a little ugly, but
handmaid is as handmaid does, and I'm sure we've all seen a lot worse.

Paul Burke


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