HELP : FLASH MEMORY TEST

Hi,

       I would like to learn about memory tetsing , mainly flash
memory test. Can anybody help me in providing documents for the same.
I have searched in net, without proper guidance I could not come to a
conclusion which is useful. Please.

Thanks and Regards
Sooraj Sasindran

On Apr 19, 1:05 am, soorajsasindra...@gmail.com wrote:
> Hi,
>
>        I would like to learn about memory tetsing , mainly flash
> memory test. Can anybody help me in providing documents for the same.
> I have searched in net, without proper guidance I could not come to a
> conclusion which is useful. Please.
>
> Thanks and Regards
> Sooraj Sasindran

What are you testing it for? To see if it still works or if the data
stored in the memory is still correct?

I've not come across testing of Flash memory operation in an embedded
system and I guess that's for two reasons -
1. It is often your main program memory and if it isn't working your
system isn't going to run anyway,
2. To test it properly you need to erase and write to the Flash memory
and Flash memory chips have a limited number of erase write cycles, so
if you test regularly then you will cause the Flash to fail too soon.

If you are testing to make sure that the data hasn't been corrupted
then the problem is the same as testing program ROM (which can also
suffer from reason 1. above). The typical approach here is to have a
checksum over the data in ROM stored at some place in the ROM and
check at start up that the checksum is correct.

- Charles

On Apr 18, 6:05 pm, soorajsasindra...@gmail.com wrote:
> Hi,
>
>        I would like to learn about memory tetsing , mainly flash
> memory test. Can anybody help me in providing documents for the same.
> I have searched in net, without proper guidance I could not come to a
> conclusion which is useful. Please.
>
> Thanks and Regards
> Sooraj Sasindran

Hi sooraj,
I have done this before following the link given below:
http://www.esacademy.com/faq/docs/memtest/device.htm

I followed whats said in the above link.But Beware of few problems
before you start writing code!
One of the main problem I faced is ,suppose your test code is also
present in ROM ,you are going to have trouble in erasing only the part
other then your test application code.So you need to move the test
application code to RAM and start erasing Flash.
The other problem I faced was though not directly related to
flash,some parts of memory may be protected by MMU and incase you try
to step in,you will recieve an exception.So you need to remove MMU
protection (incase your cpu allows!)in areas you are willing to test.

Regards,
s.subbarayan

On Apr 19, 5:59 am, charleso <charleso...@hotmail.com> wrote:
> On Apr 19, 1:05 am, soorajsasindra...@gmail.com wrote:
>
> > Hi,
>
> >        I would like to learn about memory tetsing , mainly flash
> > memory test. Can anybody help me in providing documents for the same.
> > I have searched in net, without proper guidance I could not come to a
> > conclusion which is useful. Please.
>
> > Thanks and Regards
> > Sooraj Sasindran
>
> What are you testing it for? To see if it still works or if the data
> stored in the memory is still correct?
>
> I've not come across testing of Flash memory operation in an embedded
> system and I guess that's for two reasons -
> 1. It is often your main program memory and if it isn't working your
> system isn't going to run anyway,
> 2. To test it properly you need to erase and write to the Flash memory
> and Flash memory chips have a limited number of erase write cycles, so
> if you test regularly then you will cause the Flash to fail too soon.
>
> If you are testing to make sure that the data hasn't been corrupted
> then the problem is the same as testing program ROM (which can also
> suffer from reason 1. above). The typical approach here is to have a
> checksum over the data in ROM stored at some place in the ROM and
> check at start up that the checksum is correct.
>
> - Charles

I was actually looking to test address bus and data bus test for flash
memory. Not jus the cell test.

Thanks for responding.

regards
Sooraj Sasindran

On Apr 19, 9:34 am, ssubbarayan <ssu...@gmail.com> wrote:
> On Apr 18, 6:05 pm, soorajsasindra...@gmail.com wrote:
>
> > Hi,
>
> >        I would like to learn about memory tetsing , mainly flash
> > memory test. Can anybody help me in providing documents for the same.
> > I have searched in net, without proper guidance I could not come to a
> > conclusion which is useful. Please.
>
> > Thanks and Regards
> > Sooraj Sasindran
>
> Hi sooraj,
> I have done this before following the link given below:http://www.esacademy.com/faq/docs/memtest/device.htm
>
> I followed whats said in the above link.But Beware of few problems
> before you start writing code!
> One of the main problem I faced is ,suppose your test code is also
> present in ROM ,you are going to have trouble in erasing only the part
> other then your test application code.So you need to move the test
> application code to RAM and start erasing Flash.
> The other problem I faced was though not directly related to
> flash,some parts of memory may be protected by MMU and incase you try
> to step in,you will recieve an exception.So you need to remove MMU
> protection (incase your cpu allows!)in areas you are willing to test.
>
> Regards,
> s.subbarayan

Thanks a lot . Your document was very useful.

Regards
Sooraj Sasindran