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RE: Help for init value of SRAM in MPC 562
by Randall Young
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It is definitely possible to find different values in SRAM at power-on. Some are more common than others, but short power outages can change just a few bits.
I would suggest using a 32 bit CRC rather than a single inverted byte. That greatly reduces the chances of an error not being detected (although still not zero).
Randall Young
Sr Software Engineer
Navcom Technology, Inc.
A John Deere Company
> -----Original Message-----
> From: MPC500@... [mailto:MPC500@...] On Behalf Of
> Sudhersan Lal
> Sent: Tuesday, July 01, 2008 8:43 PM
> To: MPC500@...
> Subject: [MPC500] Help for init value of SRAM in MPC 562
>
> Hello Everyone
> Anybody know or can help me to find out more information regarding the
> initialization value of SRAM contents during power up .
> I would like to save some values in sram so that I can read that back
> after a reset , for eg saving a byte value and its compliment and check
> the consistency between these two variables . This would make sure that,
> the value is really what I saved prior to reset and not the garbage value
> which would appear in the memory after a power up.
> Any existing behavior known for mpc microcontrollers related to this?
> if it is stored like the value and its compliment , what is the
> probability of the random initial values in two bytes to be compliment of
> each other and mistaken as the good value
> Regards
> Sudhersan
>
fdpnmailgwapp3.dpn.deere.com made the following annotations
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I would suggest using a 32 bit CRC rather than a single inverted byte. That greatly reduces the chances of an error not being detected (although still not zero).
Randall Young
Sr Software Engineer
Navcom Technology, Inc.
A John Deere Company
> -----Original Message-----
> From: MPC500@... [mailto:MPC500@...] On Behalf Of
> Sudhersan Lal
> Sent: Tuesday, July 01, 2008 8:43 PM
> To: MPC500@...
> Subject: [MPC500] Help for init value of SRAM in MPC 562
>
> Hello Everyone
> Anybody know or can help me to find out more information regarding the
> initialization value of SRAM contents during power up .
> I would like to save some values in sram so that I can read that back
> after a reset , for eg saving a byte value and its compliment and check
> the consistency between these two variables . This would make sure that,
> the value is really what I saved prior to reset and not the garbage value
> which would appear in the memory after a power up.
> Any existing behavior known for mpc microcontrollers related to this?
> if it is stored like the value and its compliment , what is the
> probability of the random initial values in two bytes to be compliment of
> each other and mistaken as the good value
> Regards
> Sudhersan
>
fdpnmailgwapp3.dpn.deere.com made the following annotations
---------------------------------------------------------------------
CONFIDENTIALITY. This electronic mail and any files transmitted with it may contain information proprietary to NavCom Technology, Inc., or one of its affiliates, and are intended solely for the use of the individual or entity to whom they are addressed, shall be maintained in confidence and not disclosed to third parties without the written consent of the sender. If you are not the intended recipient or the person responsible for delivering the electronic mail to the intended recipient, be advised that you have received this electronic mail in error and that any use, dissemination, forwarding, printing, or copying of this electronic mail is strictly prohibited. If you have received this electronic mail in error, please immediately notify the sender by return mail.
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