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Discussion Groups | Piclist | EEPROM question

A discussion group for the PICMicro microcontroller. Also called the Microchip PIC, this list is dedicated to the use and abuse of this fine, simple, microcontroller. Close to topic posts are welcome, ie. general electronics.

EEPROM question - tom_bihn - Nov 30 13:19:00 2003

I've simulated my application successfully with the MPLAB simulator
and would like to program the chip soon. In my application, I have a
matrix keypad for input to check/program a PIN code. When assigning
the PIN code, I'm checking the first six digits entered compared
with a value I would put into EEPROM. Is there a way I can program
the chip once for the EEPROM values to store for a "unique serial
number" before programming it with my program?

If not, I was considering placing a routine in the startup
initialization routine to check the EEPROM locations used for the
serial number for FF at each location. If the value is FF, then the
first six keypresses after the initial power up would be written to
the EEPROM and every power up afterwards would not then allow the
programming of the SN.

If possible, I'd like to program the EEPROM seperately. I'm using an
EPIC Plus programmer from ME labs.

Thanks again,
Tom




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Re: EEPROM question - cdb - Nov 30 18:06:00 2003

If I understand you correctly,

At chip programming time - you want to burn some data into EEPROM and
subsequrntly access that data. You also need to write to EEPROM ?
during the actual running of the program.

To put data into the Pic at burn time you need to use the

data or dw keyword

org 0x2100
DATA 0x59,0x45,0x53 ;YES Then if you subsequently want to write to EEPROM you must make sure
that you only use addresses past the last bit of static data.

In the above case, the program would write to EEPROM starting from
address 03, the first available free address.
There is of course nothing stopping you from putting the data
wherever you wanted. org 2130 for example.

However some programmers won't automatically place things at org
0x2100 (for the 16 series pics, org 0xF0000 for the 18 series) and
you have to enter it manually.

Colin

On Sun, 30 Nov 2003 18:19:53 -0000, tom_bihn wrote:
::I've simulated my application successfully with the MPLAB simulator
::and would like to program the chip soon. In my application, I have
a
::matrix keypad for input to check/program a PIN code. When assigning
::the PIN code, I'm checking the first six digits entered compared
::with a value I would put into EEPROM. Is there a way I can program
::the chip once for the EEPROM values to store for a "unique serial
::number" before programming it with my program?

--
cdb, on 01.December.2003

I have always been a few Dendrites short of an Axon and believe me it
shows.

Light travels faster than sound. That's why some people appear bright
until they speak!




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Re: EEPROM question - xob_jt - Dec 1 14:27:00 2003


Tom

As was pointed out in another reply use DE or one of those data
statements. This is an example of storing 123456 in an eeprom of a
16f628 at eeprom address 0

Org 8448
DE 1
DE 2
DE 3
DE 4
DE 5
DE 6

BTW have a look at my Password program its written in BASIC here
at http://users.picbasic.org/

Then goto Projects / control

But don't forget to have a good look around at the rest of the stuff
as well, especialy the GAMES and PPRINT, which is in How to / Make
The Most of Proton Plus

As far a saving passwords with the epic just use the Serial number
feature.

Tim --- In , "tom_bihn" <tbihn@n...> wrote:
> I've simulated my application successfully with the MPLAB
simulator
> and would like to program the chip soon. In my application, I have
a
> matrix keypad for input to check/program a PIN code. When
assigning
> the PIN code, I'm checking the first six digits entered compared
> with a value I would put into EEPROM. Is there a way I can program
> the chip once for the EEPROM values to store for a "unique serial
> number" before programming it with my program?
>
> If not, I was considering placing a routine in the startup
> initialization routine to check the EEPROM locations used for the
> serial number for FF at each location. If the value is FF, then
the
> first six keypresses after the initial power up would be written
to
> the EEPROM and every power up afterwards would not then allow the
> programming of the SN.
>
> If possible, I'd like to program the EEPROM seperately. I'm using
an
> EPIC Plus programmer from ME labs.
>
> Thanks again,
> Tom



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