BQ78350-R1: CRC Calculation on ManufactureAccess

Paul Klarhoefer1

Intellectual 365 points

Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQSTUDIO

Hi,

I'm in the middle of implementing bq78350-r1 communication via SMBUS.

So far everything is working, but one thing I can't figure out with CRC:

When I do a normal read for instance SoC, I do receive from bq78350-r1 a CRC, which I can also calculate. For example:

Read SoC (0x0d) leads to following response: 64 00 92

0x92 is the CRC received from bq78350-r1

So if we calculate the CRC with the following data like described in www.ti.com/.../slua475.pdf:

0x16 (slaveID) 0x0d (memAddr) 0x17 (slaveID) 0x64 (data) 0x00 (data) the result is: 0x92

It can be checked also here: www.sunshine2k.de/.../crc_js.html

But If I execute a read command with manufacture Access, e.g. for the Manufacturing Status (0x0057), I receive the following data: 0x2 0x10 0x00 0x84

0x84 is the CRC received from bq78350-r1

The received data is correct, I checked it with bqstudio, so I don't think it is a hardware communication problem here.

No matter how I try to calculate CRC from that, I never get the CRC, which I receive from the chip.

I would guess it's the same logic for crc data packet like:

0x16 (slaveID) 0x44 (memAddrBlockAccess) 0x17 (slaveID) 0x2 0x10 0x00

But that matches not the received CRC. Can you please help me which bytes are taken into account in CRC calculation on a ManufactureAccess Read?

Thanks in advance

Paul

I also tried to insert the

over 5 years ago

0 David Hien over 5 years ago

TI__Genius 10830 points

Hallo Paul,
Our engineers will be back tomorrow from the Holidays and one of them will answer your question shortly.
BTW is there something missing in your post (I see "I also tried to insert the" after your signature)?

0 Paul Klarhoefer1 over 5 years ago in reply to David Hien

Intellectual 365 points

Hi,

ignore it after the signature. I was trying some stuff around got somehow the correct CRC. But I have still no idea, which bytes are taken into account for the CRC in reading registers via ManufactureAccess.

Greetings

Paul

0 Matt Sunna over 5 years ago

TI__Guru* 81034 points

Hi Paul,

Have you tried calculating the CRC from 0x17 0x2 0x10 0x00? I think that will give the correct value.

I think the ManufactureAccess block read commands are different. I can check into this more if this doesn't resolve your issue.

Regards,

Matt

0 Matt Sunna over 5 years ago in reply to Matt Sunna

TI__Guru* 81034 points

Hi Paul,

I tested this out today and you can see my result below. The PEC calculation does include the entire sequence. When you read from 0x0057, you should receive 4 bytes. You can see that the PEC is calculated as expected for 0x16 0x44 0x57 0x00 0x00 0x80 = 0x84. When reading 0x44, you should also see the command (0x0057).

Best regards,

Matt

0 Paul Klarhoefer1 over 5 years ago in reply to Matt Sunna

Intellectual 365 points

Hi Matt,

Ok, but when I calculate with my algorithm the CRC for your received message: 0x16 0x44 0x57 0x00 0x00 0x80

I get 0x38, but you received 0x84.

For quick calculation I use this one here, which matches the correct SOC for all readouts that are normal, but for manufacture access it does not match (and also not my CRC algorithm) : www.sunshine2k.de/.../crc_js.html

0 Matt Sunna over 5 years ago in reply to Paul Klarhoefer1

TI__Guru* 81034 points

Hi Paul,

Sorry, I had a typo in the last response. The sequence is 0x16 0x44 0x17 0x04 0x57 0x00 0x00 0x80. The CRC is 0xB4.

Matt

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BQ78350-R1: CRC Calculation on ManufactureAccess