topic Re: Question about 5744P memory ECC check code storage location in MPC5xxx

Question about 5744P memory ECC check code storage location

建浩章 — Thu, 08 Aug 2019 15:36:46 GMT

Recently I am looking at the 5744P memory ECC module. I have a question about whether ECC checkBit takes up normal memory space. Because I read from the datasheet that the ECC checksum is stored in memory, but I don't know if this memory refers to special memory or normal memory (384KB RAM or 2.5M Flash). I hope someone will help me answer it, thank you very much.

Re: Question about 5744P memory ECC check code storage location

lukaszadrapa — Fri, 09 Aug 2019 07:24:11 GMT

Hi,

the ECC bits are hidden for users. Each double word (64bit) has additional hidden bits for ECC. It does not decrease size of the flash which can be used, of course.

Regards,

Lukas

Re: Question about 5744P memory ECC check code storage location

建浩章 — Fri, 09 Aug 2019 07:49:23 GMT

Thank you for your reply. What you mean by your reply is that the ECC check digit is placed in a place that is not open to the user. I have another problem. The contents of Flash are generally brushed in by the programmer. When the program and data are flashed into the 5744P flash through the programmer, will the CPU perform ECC verification?

Re: Question about 5744P memory ECC check code storage location

lukaszadrapa — Mon, 12 Aug 2019 04:45:44 GMT

Hi,

ECC can't be turned off, it's checked anytime when you read data or fetch an instruction from flash or from RAM.

Regards,

Lukas

Re: Question about 5744P memory ECC check code storage location

建浩章 — Fri, 16 Aug 2019 00:36:29 GMT

Hi，

Thank you very much for your reply. I still have some doubts. When I use the programmer to brush into the program, there should be no CPU participation at this time. Is there no corresponding ECC check code stored in the special memory? If there is no corresponding ECC check code stored in special memory, then when the program runs, when the CPU captures the instructions in the PFlash, how to do ECC check?

Re: Question about 5744P memory ECC check code storage location

lukaszadrapa — Fri, 16 Aug 2019 09:28:19 GMT

Hi,

I do not understand your question but as I wrote, "it's checked anytime when you read data or fetch an instruction from flash or from RAM". There's always ECC, it doesn't matter if memory cell is accessed by CPU or other bus masters. If corrupted data are access by CPU, Machine Check IVOR1 exception is triggered.

Regards,

Lukas

Re: Question about 5744P memory ECC check code storage location

建浩章 — Sat, 24 Aug 2019 06:12:43 GMT

Thank you very much for your help. Let me understand some concepts about ECC.