Periodic self test of memory

Since the flash (at least in the program space) does not change, using the CRC and checking against a known CRC value is a good method of checking it. See chapter 18 of the Technical Reference Manual. You can use the PBIST controller to do extensive tests of RAM, but it destroys the contents, so this is usually only done at startup. PBIST is described in chapter 9 of the TRM.

You might want to download the new version of the datasheet. It was just updated last night.

Thanks bob for your reply,

Each time in periodic test CRC to be calculated and compared with stored CRC of flash, this method???

Yeah I understood pbist. But which is better way to do RAM test periodically by internally???


Best regards
Anil

Hi Anil,
As Bob pointed out, running PBIST on the RAM is not a suitable method if you want to do it periodically since the content of the RAM will be destroyed. Remember the stacks are located in RAM and you might run the risk of crashing the program. The CRC on the RAM is also not a good solution because the content of the RAM will be changing dynamically. So you don't really know the golden signature to compare with.

So CRC on flash is a good solution if you want to do it periodically. I will recommend PBIST on RAM on startup. Bear in mind that both flash and RAM are protected with ECC for every access during run time.

Hi Charles,

I understood RAM and Flash tests. But what I asking is " Can processor(RM57) do flash test periodically by setting some bit internally??"

Thanks

Anil

Hi Anil,
When you say some bit internally, do you mean a bit in the processor? If this is the question then it is no. You can pre-program a flash location with an intentional 1-bit error or a 2-bit error. Periodically you can have the CPU to read this location and you will see either 1-bit ECC or 2-bit ECC error detected by the CPU. This method can be used as a diagnostic to check that the ECC logic in the processor is working.

Hi Anil,
Do you have any more questions? Can you please click the verify answer button if your question is answered?

Sorry charles, but how to do that??

Hi Anil,
It is a bit weird that I don't find the verify answer button at the bottom for this particular post. I will close this thread if you have no further questions.

Ok charles.

Thank you for your reply

I will close this thread now.