MCT8329A: MCT8329a CRC calculation appears off by an xor of 0xF

Pierre Baudin

Prodigy 30 points

Part Number: MCT8329A

output from logic analyzer (MCU agrees):
```

write to 0x60 ack data: 0xD0 0x00 0x80
read to 0x60 ack data: 0x02 0x4D 0x40 0x7F 0xBE 0x00'

```

0x60 write translates to 0xC0 (0x60 <<1)

0x60 read translates to 0xC1 (0x60 << 1 | 1)

full byte sequence (gives a result of 0xc0 0xd0 0x00 0x80 0xc1 0x02 0x4d 0x40 0x7f ) for CRC calculation with generator 0x07 (x^8 + x^2 + x + 1) gives output 0xB1

www.sunshine2k.de/.../crc_js.html

This disagrees with system output of 0xBE

If I end CRC calculation with xor 0x0F then i get the "correct" value as output by the MCT8329a

I tested this on a 5+ registers and it was consistent.

I don't know why this is the case.

Any thoughts? Can anyone replicate this?

over 2 years ago

0 Venkatadri Shantaram84961 over 2 years ago

TI__Mastermind 26332 points

Hi Pierre,

I will get back to you on this by this weekend.

Thanks and Best Regards,

Venkatadri S

0 Pierre Baudin over 2 years ago

Prodigy 30 points

I am also noticing strange CRC output when I try to write a register.

Not having any luck with the algorithm I use to generate the CRC read

Logic analyzing the output of the EVM board for a register write operation shows:

CRC value of 0x07 for the write operation: 0xC0 0x50 0x00 0xE8 0x00 0x80 0x00 0x00

I can't find any way to make the 8 bit CRC algorithm from the datasheet generate 0x07 from this byte string.

I get 0xDC (or 0xD3 if I apply the final xor 0x0F as i do for the read calculation)

0 Venkatadri Shantaram84961 over 2 years ago in reply to Pierre Baudin

TI__Mastermind 26332 points

Hi Peirre,

There data sheet not showing the Initial Value used. The initial value is 0xFF. In the link you provided please change the Initial Value to 0xFF and it matches.

Thanks and Best Regards,

Venkatadri S

Motor drivers

Motor drivers forum

MCT8329A: MCT8329a CRC calculation appears off by an xor of 0xF