ADS131A02: ADS131A02 CRC16 formula ?

Hidehiko Kaya

Intellectual 660 points

Part Number: ADS131A02
Other Parts Discussed in Thread: ADS131M02-Q1,

Hi experts,

I'm implementing a driver software to communicate from F2838x to ADS131Mx via SPI.

So far we received a below data when we transmit NULL command.

Response = 0x0503

Ch0, Ch1 data (24-bit)

And CRC (16-bit, 0 padding)

However I'm confusing following statements in TRM.

Because a size of WORD is 24-bit, it is not aligned to 16-bit.

Could you let us know what is a good sample ?

SWRA111E.pdf is suitable for this problem ?

ーーーーー

8.3.12 Communication Cyclic Redundancy Check (CRC)

The CRC word is 16 bits wide for either input or output CRC. Coverage includes all
words in the SPI frame where the CRC is enabled, including padded bits in a 32-bit word size.

ーーーーー

Best regards,

Hidehiko

2 months ago

0 Dale Li 2 months ago

TI__Mastermind 35600 points

Hi Hidehiko,

The ADC's part number you input led to a confusion because you mentioned ADS131A02 in the title of your query and the field of Part Number, but you also mentioned ADS131Mx ADC in your description and ADS131M02-Q1 was shown in your image, you also copied the content from ADS131M02-Q1 datasheet, so I think you are asking ADS131M02-Q1 ADC.

NULL command is a 16-bit command but the word size is 24-bit, so the input CRC should count 24 zeros not 16 zeros. Please check my answer in the following E2E thread:

ADS131M03: CRC difficulties

Regards,

Dale

0 Hidehiko Kaya 2 months ago in reply to Dale Li

Intellectual 660 points

Hi Dale,

Thank you for your information.

Regarding to part number, we can select only ADS131A02 when I create a new question.

And I get correct result crc values like below Excel files.

I'm happy if you check my calculate process.

(1)

Input : 0x0 0x0 0x0

crc vaule : 0xCC9C (as you mentioned)

(2)

Input : 0x1 0x2

crc vaule : 0x0E7C

TI_CRC16.xlsx

And I checked on below site.

http://www.sunshine2k.de/coding/javascript/crc/crc_js.html

Best regards,

Hidehiko

0 Dale Li 2 months ago in reply to Hidehiko Kaya

TI__Mastermind 35600 points

Hi Hidehiko,

My colleague, Bob, published an app note (Communication Methods for Data Integrity Using Delta-Sigma Data Converters application report) which provides more information about CRC implementation, including example code.

Also, the following E2E thread could be a good reference for you: ADS131A04: CRC Calculation

Regards,

Dale

0 Hidehiko Kaya 2 months ago in reply to Dale Li

Intellectual 660 points

Hi Dale,

Thank you for more detailed information.

>3.1.1 Using XOR Bitwise Computation

That code works fine.

Best regards,

Hidehiko

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ADS131A02: ADS131A02 CRC16 formula ?