Searching \ for '[PIC]: Reburning OTP with new ORG?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/devices.htm?key=pic
Search entire site for: 'Reburning OTP with new ORG?'.

Exact match. Not showing close matches.
PICList Thread
'[PIC]: Reburning OTP with new ORG?'
2000\08\02@172334 by Lorick

picon face
Someone suggested the next time I put something in an OTP device, I make the
ORG higher so I can later reburn the lower region and overwrite the reset
area with the new lower ORG as long as the new ORG only has bits changing
from 1 to 0 in the number so that they can be burned and updated.

Does this work, or is it a nice fairy tale?  I would first think the
picstart would yell at me that it's not a blank device even if I technically
can burn the untouched 1's sitting in the OTP.

The reason all this came up is because I put some 16c65 code in an OTP and
now I find I would like longer output port On times so I'm forced for this
one unit to add hardware RC/Transistor delays between the pic and the other
control lines being driven...the next burns will have software increased
delays of course.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

2000\08\02@175436 by Dale Botkin

flavicon
face
On Wed, 2 Aug 2000, Lorick wrote:

> Someone suggested the next time I put something in an OTP device, I make the
> ORG higher so I can later reburn the lower region and overwrite the reset
> area with the new lower ORG as long as the new ORG only has bits changing
> from 1 to 0 in the number so that they can be burned and updated.
>
> Does this work, or is it a nice fairy tale?  I would first think the
> picstart would yell at me that it's not a blank device even if I technically
> can burn the untouched 1's sitting in the OTP.

CAVEAT:  I have not used a PICSTART programmer, so I don't know if it will
let you, and I've done this with other devices but not a PIC.

With some advance planning, yes, this can be done with OTP devices.  I
have done a similar thing with an OTP 8751 device - needed to change table
values.  Fortunately, you can change 1's to 0's without re-burning the
device.  As long as your programmer will allow you to skip the blank check
and program the locations regardless of their current state, you should be
able to turn 1's to 0's.  It's something I would only recommend as an
emergency measure, really, but it's kind of neat to see it work --
especially when it saves the day on a doomed project!

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

2000\08\02@205954 by Tony Nixon

flavicon
picon face
Lorick wrote:
>
> Someone suggested the next time I put something in an OTP device, I make the
> ORG higher so I can later reburn the lower region and overwrite the reset
> area with the new lower ORG as long as the new ORG only has bits changing
> from 1 to 0 in the number so that they can be burned and updated.
>
> Does this work, or is it a nice fairy tale?

I used to use this technique all the time when burning JW chips. Saves
time by not having to UV erase the chip when debugging.

You can alter GOTO, CALL, Literal values or any ROM value using this
method.

As long as the new value only changes 1 bits to 0 then it will work. It
will not work if the new value changes 0 bits back to 1.

Just logically AND the old and new values that you want and that will
give the result.

eg

    org 1F00h

changed to

    org 1E00h  will work

    1F00 AND 1E00 = 1E00



    org 1000h

changed to

    org 0F00h will not work as you want

    1000 AND 0F00 = 0000


--
Best regards

Tony

ICmicro's
http://www.picnpoke.com
spam_OUTsalesTakeThisOuTspampicnpoke.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

2000\08\02@225815 by Jinx

face picon face
This method works on the Mot series except bits are inverted, ie
0's go to ones. eg org can go from $180 to $380 but not $280. A
small prog like most progs are will be small enough to get perhaps
1/2 dozen versions/hopeful attempts into a micro. You don't run out
of space, rather you run out of viable org addresses. Saves money
if you can use an OTP only twice

>      org 1F00h
>
> changed to
>
>      org 1E00h  will work
>
> Tony

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

2000\08\03@002318 by hard Prosser

flavicon
face
With planning it's not a problem.
If you place a jump at the start of the program with some unprogrammed area
following it you can nop out the old jump and re-write the new one. This
can give you access several times as long as you leave enough space to nop
out the long jumps.

You may need to leave space for updated interrupt routines also so it can
get a bit messy but I've used it up to about 6 times on a single '73B. (JW
version SMT devices aren't available so how else can you polish the
software on the target?)

Also - watch your paging - especially if you are using lookup tables but
even jump instructions can get fouled up at the boundary.

PICSTART / MPLAB does come up with a warning message but you can override
it.


If you need more info, contact me & I'll send more detail (I'll have to
refresh myself on the details first).

Richard P




                   Dale Botkin
                   <dale@BOTKIN.O        To:     .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
                   RG>                   cc:
                   Sent by: pic          Subject:     Re: [PIC]: Reburning OTP with new ORG?
                   microcontrolle
                   r discussion
                   list
                   <PICLIST@MITVM
                   A.MIT.EDU>


                   03/08/00 09:30
                   Please respond
                   to pic
                   microcontrolle
                   r discussion
                   list





On Wed, 2 Aug 2000, Lorick wrote:

> Someone suggested the next time I put something in an OTP device, I make
the
> ORG higher so I can later reburn the lower region and overwrite the reset
> area with the new lower ORG as long as the new ORG only has bits changing
> from 1 to 0 in the number so that they can be burned and updated.
>
> Does this work, or is it a nice fairy tale?  I would first think the
> picstart would yell at me that it's not a blank device even if I
technically
> can burn the untouched 1's sitting in the OTP.

CAVEAT:  I have not used a PICSTART programmer, so I don't know if it will
let you, and I've done this with other devices but not a PIC.

With some advance planning, yes, this can be done with OTP devices.  I
have done a similar thing with an OTP 8751 device - needed to change table
values.  Fortunately, you can change 1's to 0's without re-burning the
device.  As long as your programmer will allow you to skip the blank check
and program the locations regardless of their current state, you should be
able to turn 1's to 0's.  It's something I would only recommend as an
emergency measure, really, but it's kind of neat to see it work --
especially when it saves the day on a doomed project!

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2000\08\03@025946 by Tsvetan Usunov

flavicon
face
> Someone suggested the next time I put something in an OTP device, I make
the
> ORG higher so I can later reburn the lower region and overwrite the reset
> area with the new lower ORG as long as the new ORG only has bits changing
> from 1 to 0 in the number so that they can be burned and updated.
>
> Does this work, or is it a nice fairy tale?  I would first think the
> picstart would yell at me that it's not a blank device even if I
technically
> can burn the untouched 1's sitting in the OTP.

no problem to do it with PICs
I'm doing this permanently - sometimes forget to set the right fuses,
sometimes change constants.
PICSTART will warn you, but will ateampt to program and if you didn't set
the security fuse everythink will be OK.

Regards
Tsvetan
---
PCB prototypes for $26 at http://run.to/pcb

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2000\08\03@063706 by Alan B. Pearce

face picon face
>It's something I would only recommend as an
>emergency measure, really, but it's kind of neat to see it work --
>especially when it saves the day on a doomed project!

It can also earn brownie points with the management for this very reason when
you manage to do these sort of "black magic" and "snake oil" tricks.

I believe it was for this reason Intel specified hex 00 as the NOP code in the
8080 series micros. It allowed easy modification of the code in an eprom (a bit
like using the DEL code on paper tape to correct an error) so you could jump to
an unused bit by NOP'ing the erroneous code.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2000\08\04@075600 by Lorick

picon face
----- Original Message -----
From: "Richard Prosser" <Richard.ProsserspamKILLspamENERGY.INVENSYS.COM>

> If you place a jump at the start of the program with some unprogrammed
area
> following it you can nop out the old jump and re-write the new one.

> If you need more info, contact me & I'll send more detail (I'll have to
> refresh myself on the details first).

I'd like more info on how to implement this method of updating with nops as
you describe and writing the new jump.  I would just want to make sure I do
know what I'm doing before I try to start my planning.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

More... (looser matching)
- Last day of these posts
- In 2000 , 2001 only
- Today
- New search...