STEVAL-BMS114TX no signs of life

[dennis3]

Hello,

I am looking for an IC to monitor cell voltages of a 12s lipo battery.

I found the L99BM114 IC. To get started, I bought the STEVAL-BMS114TX.

Currently, I have connected 12 resistors in series to my lab supply with 48v. In between these resistors, I soldered cables and connected them to the Connector 7 (P1). On Connector 5 (CN1) I connected an STM32 Development MCU. With that MCU, I try to communicate via SPI. On Connector 2 (CN3) I connected my MCU: GND to GND, VIO to 3V3 and VDD to 5V. 

My Problem is that I don't get any sings of life from that board via SPI. The Cellcoltages measured at the PCB are correct. I also tried to pull pin20 (SPIEN) of the IC to VCOM, but this doesn't help. Can you give me a point where I can start?

Kind regards and thanks in advance

Dennis

[ahsrabrifat]

Are you sure that VCOM is active and present at the time you're pulling SPIEN high?

Try probing the SPIEN pin and VCOM with a scope or meter to verify both are high (typically VCOM ~3.3V).

[Max VIZZINI]

Hi,

It is not trivial to help you debug considering that there could be some issue in both the HW and the SW.

In particular, for the software, it is important that you go through the initialization process and addressing process before being able to communicate with the board.

We have running examples on SPC58 microcontroller. You can look at the source code inside AutoDevKit and try to mimic the same steps with STM32.

You can refer to the following User Manual: 

https://www.st.com/resource/en/user_manual/um3185-getting-started-with-autodevkit-battery-management-system-bms-evaluation-boards-stmicroelectronics.pdf

at paragraph 1.3 there is the description of the AEK-POW-BMSWTX that is equivalent to the board you are using.

The demo code is present in AutoDevKit Studio www.st.com/autodevkitsw 

After download and installation, you should select the Chorus 4M microcontroller and import the BMS Chain examples.

Finally, we have a board much closer to the system you are trying to build.

You can refer to AEK-POW-BMSLV https://www.st.com/en/evaluation-tools/aek-pow-bmslv.html 

Last point: even if you are using only 12 cells, you need to connect in series all the 14-cell monitoring and balancing pins of the IC otherwise the voltage reading will not be correct.

I have attached a quick start guide.

Best Regards,

AutoDevKit Team

[dennis3]

Thank you for your reply.

I connected SPIEN to VCOM via a two connected measuring lines (before power up of the board)

My problem is VCOM is at 0V. And I don't get why.
VBAT: Is at 48V (to GND)

TP1: Is at 48V (to GND)

VREG: Is at 0V (to GND) (LED D2 is off)

NPNDRV (EXTDRV)(Gate on Q1): Is at 0V

This means the IC is in Sleep, Silent Balancing, OFF phase of Cyclic Wakeup like mentioned in the Datasheet on page 53. 

Do you know why my IC is in Sleepmode? I checked if a "GPIO Signal" is possible, but default GPIO_7 is not configured as wakeup pin (GPIO_WUP_EN) Do you know how to get it out of sleep mode?

Thank you very much in advance! 

[dennis3]

Thank you very much. I think my IC is in sleep mode (my description is one reply above yours). I am currently looking for a way to get it out of sleep mode.

Furthermore, I connected cell measure pin 13 and 14 to my 12th cell, there should be no problem.

Thank you for the given software information, I will work on this.

[Max VIZZINI]

Hi,

Few comments trying to help...

- SPIEN should be connected to GND and should not go to VCOM because the board contains the transceiver, and the internal transceiver mode should not be activated. In addition, when you forced the SPIEN pin to VCOM, did you disconnect the resistor bringing the pin to GND? If not, you are forcing the VCOM to GND.

- There is a given time around 120sec that the IC wait to establish the SPI communication with the MCU. if this does not happen in time, the device will go in sleep mode.

- When you connect the VBAT (aka the cells), do you see the LED D2 on? If yes, then you can check the VCOM voltage,  and you should be able to communicate with the MCU. If the LED does not turn on there could be a damage in the board, particularly if you see the 48V on TP1 pin.

Best Regards,

AutoDevKit Team