Header CRC in Freescale example for MCU : 16-bit MC9S12XF512MLM

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Header CRC in Freescale example for MCU : 16-bit MC9S12XF512MLM

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Kartoon67
Contributor III

Hi everybody,

 

I have some problem ton calculte the header CRC from a frame. For exemple, in the example freescale, the header CRC for a transmit frame SLOT09 is : 0x03FC.

 

When i calculate it, i find 0x2d7.

 

Caracteristic of the frame :

Header CRC = 0x03FC

Sync frame indicator : 1

Startup frame indicator : 1

ID : 9

Payload length : 16

 

So i have my frame is equal to that : 1100 0000 0100 1001 0000

I compute there with the polynomial sequence define in the Flexray criteria : 1011 1000 0101 (x^11 + x^9 + x^8 + x^7 +x^2 +1)

 

Why I don't find the same Header CRC?

 

Thank you in advance,

 

Best regards,

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Kartoon67
Contributor III

I have lerned by the Flexray Protocol specification that there is a specifical way to use the data from Header CRC.

 

By the documentation, i think that the data is composed by :

 

LSB Payload -> MSB Payload ->LSB FID -> MSB FID-> SU -> SY

 

Are here somebody who can say me that is it right or not? Because in any documentation by freescale, this calculation is really explain correctly...

 

Thanks in advance,

 

Regards,

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