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PICList Thread
'Checksum'
1999\09\17@134408 by David Williams

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Hi all,

I've got to do a checksum on program memory and compare it to a known
checksum.  I want to store the known checksum on the PIC.  Is there
anywhere I can store it besides in the program memory or those ID
locations?

And if i did store it in those ID locations, how do I read it?
Thanks

DAve

1999\09\17@143014 by Sean H. Breheny

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Hi Dave,

Which PICs are you talking about? Most PICs cannot read their own program
memory,so they cannot perform such a checksum test. I am not very familiar
with the new PICs which have come out in the last few months. If I remember
correctly, however, they CAN read program memory. If you are using one of
these PICs, you can store the checksum either in the data EEPROM, or in the
program memory (which is also EEPROM). If you did the latter, you could use
a CRC routine,which is nice because the checksum itself is considered a
part of the data being checked,and the CRC polynomical division will yield
a remainder of zero when performed on data which is terminated in a valid
checksum,otherwise,it will return a non-zero number.

Sean

At 03:13 PM 9/17/99 -0230, you wrote:
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| Sean Breheny
| Amateur Radio Callsign: KA3YXM
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1999\09\17@153215 by M. Adam Davis

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David Williams wrote:
>
> Hi all,
>
> I've got to do a checksum on program memory and compare it to a known
> checksum.  I want to store the known checksum on the PIC.  Is there
> anywhere I can store it besides in the program memory or those ID
> locations?

Not unless your pic has internal data eeprom.

> And if i did store it in those ID locations, how do I read it?

I don't believe so.

-Adam

> Thanks
>
> DAve

1999\09\19@015046 by Jim Robertson

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At 15:13 17/09/99 -0230, you wrote:


Only the 16F87x and 17cxxx parts can read there own program memory.
You cannot read the ID locations from within program memory on any
PIC.

Jim

{Quote hidden}

Regards,

Jim Robertson
NEWFOUND ELECTRONICS
________________________________________
Email: .....newfoundKILLspamspam@spam@pipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.
________________________________________

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