BQ78350-R1: Manufacturer Access PEC CRC-8 Calculation Problem

Fatih TAHTASAKAL

Part Number: BQ78350-R1

hi
I can get data between 78350-R1 and MCU using sbs commands. I can calculate crc values such as voltage, current, soc. No problem.

For example soc;when i send 0D, i read data; 1D 00 0A.
I calculate crc by adding 17 to the first byte.
for 171D00 CRC is 0A. No problem.

But i cant calculate CRC for OperationStatus blocks.

Operation Status A is : 0x0107
Operation Status B is : 0x0000

For example I want to read operation status. i send 0x54 and incoming data is ;
0x04(I think it's crc)
0x07
0x01
0x00
0x00

0x00 0x00 0x01 0x07 is operation status.
I couldn't find the crc value "0x04" for these values. How do I calculate this crc value?

Fatih

over 3 years ago

0 Matt Sunna over 3 years ago

TI__Guru* 81035 points

Hi Fatih,

The "0x04" in this case is the byte count, not the CRC.

This site is useful for the CRC calculation: https://crccalc.com/

This previous thread may also be helpful: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/869904/bq78350-r1-crc-calculation-on-manufactureaccess

Best regards,

Matt

0 Fatih TAHTASAKAL over 3 years ago in reply to Matt Sunna

Prodigy 80 points

Hi Matt

Thank you for answer. But i dont undersrand that Is there no crc in the incoming message? Which byte is the crc value in the incoming message?

0x04 0x07 0x01 0x00 0x00 which byte crc? If no crc byte, how do i confirm the message is correct?

0 Matt Sunna over 3 years ago in reply to Fatih TAHTASAKAL

TI__Guru* 81035 points

Hi Fatih,

I do not know why there is no CRC on the read back from 0x54. Do you have PEC enabled in the device settings? Do you the same behavior when reading from other status registers?

Regards,

Matt

0 Fatih TAHTASAKAL over 3 years ago in reply to Matt Sunna

Prodigy 80 points

Hi Matt

there is the same problem while reading from other status registers. the problem is that reading data has no crc. for only status registers.

I can read crc, for voltage, current, relative state of charge. This is ok. No problem. But i cant read crc for operationstatus or safetystatus.

I activate pec by changing the HPE bit. Is there a different bit for status registers to activate pec?

How can i activate pec for these statuses registers?

Regards

Fatih

+1 Matt Sunna over 3 years ago in reply to Fatih TAHTASAKAL

TI__Guru* 81035 points

Hi Fatih,

The CRC should work the same on these registers too. When you set the HPE bit, you need to also send the RESET() command for the change to take effect.

I just tested the 0x54 OperationStatus() command on my EVM and it works as expected.

Best regards,

Matt

0 Fatih TAHTASAKAL over 3 years ago in reply to Matt Sunna

Prodigy 80 points

Hi Matt

Thank you for answer. Problem solved. I made a mistake in the codes in the mcu. The problem was that I was reading 5 bytes in the mcu code. I set 6 bytes to read and crc bytes are in the reading data. Many thanks for your support and help.

Regards

Fatih

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BQ78350-R1: Manufacturer Access PEC CRC-8 Calculation Problem