topic Re: CRC from partial calculations in LPC Microcontrollers

CRC from partial calculations

juanabelaira — Mon, 05 Jun 2017 12:27:38 GMT

Hello, I need to reckon the CRC of a long file in an external SPI memory so I take blocks into RAM and calculate their partial CRCs with the functions in LpcOpen library. I couldn't find how to obtain the total CRC, can anyone point me in the right direction? Thanks.

Re: CRC from partial calculations

jeremyzhou — Tue, 06 Jun 2017 01:59:42 GMT

Hi Juan Abelaira,

Thank you for your interest in NXP Semiconductor products and

the opportunity to serve you.

I was wondering if you can tell me the chip you used.

Have a great day,

TIC

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Re: CRC from partial calculations

juanabelaira — Tue, 06 Jun 2017 07:19:03 GMT

LPC1518

Re: CRC from partial calculations

jeremyzhou — Wed, 07 Jun 2017 02:05:20 GMT

Hi Juan Abelaira,

In the LPCOpen library of the LPCXpresso LPC1549, the crc demo has exemplified the CRC engine for 8-bit, 16-bit, and
32-bit CRC computation, please refer to the demo for details.

Have a great day,
TIC

Re: CRC from partial calculations

juanabelaira — Wed, 07 Jun 2017 07:15:43 GMT

That example (if we are talking about the same) takes the CRC of a limited and complete set of data. It doesn't help with my problem, as it is different. I'll state it again: My data to calculate the CRC is only available in blocks because it's larger than the MCU's RAM. So I take, let's say, 4 KB, calculate a partial CRC, read the next 4KB block and so on.

Re: CRC from partial calculations

martinlorenz — Thu, 20 Sep 2018 10:02:05 GMT

I think you have to implement the crc function manually, because you will need access to the internal state of the crc polynomial which must be handed from one block of data to the next one.

Re: CRC from partial calculations

June — Mon, 05 Aug 2019 02:42:47 GMT

Hi Juan,

Did you manage to get it to work? Can you share your working code?

Thanks.