Power ManagementのトピックMC33772 always output Null response. (Data is all zero)

MC33772 always output Null response. (Data is all zero)

cbg9157 — Thu, 25 Jun 2020 01:55:13 GMT

Hi, I want to implement the battery management system using MC33772B chip, but now got some problem.

1. Problem : MC33772B always response all zero data included correct CRC although send measurement request.

2. Information

1) Mode: SPI communication

2) Clock polarity : LOW

3) Clock Phase : Falling edge

4) Using device: 1

5) Using battery cell: 3

3. Sequence (Refer to example source code)

1) Wake up (CSB pin - low to high)

2) Software reset (I guess BCC is no response because CID wasn't assigned)

3) Assign CID

-. BCC_CID_UNASSIG Read message (First message after reset - Response all zero and the correct CRC)

-. CID setup and send to BCC (CID: 1) / but, response is all zero and the correct CRC again.

MCU send many request message (e.g. Measurement, Cell balancing,.etc), but BCC chip always response all zero and the correct CRC (0x0 0x0 0x0 0x0 0xB2).

I don't know what is solution about this problem.

Re: MC33772 always output Null response. (Data is all zero)

JozefKozon — Mon, 29 Jun 2020 06:59:27 GMT

I have contacted an application engineer dealing BMS. Please answer her questions in the description.

DESCRIPTION

Did the customer tried with another IC on the same setup?

And do you know how they read the BCC response?

Did the customer try checking the signal on an oscilloscope?

With Best Regards,

Jozef

Re: MC33772 always output Null response. (Data is all zero)

paulung — Mon, 06 Jun 2022 14:46:20 GMT

Hi cbg9157,

I have the same issue - the MC33772B always returns zero data with valid CRC. Just wonder if you know the cause and how to fix it.

Many thanks.

Paul.

Re: MC33772 always output Null response. (Data is all zero)

paulung — Thu, 09 Jun 2022 00:48:33 GMT

It looks like the 33772B always return zero data with valid CRC in response to invalid frame. In my case the byte order in the frame was incorrect. Hope it helps someone else who might run into the same issue.

Paul.