bq40z60 bring-up in custom hardware

user4401865

Other Parts Discussed in Thread: BQSTUDIO, BQ40Z50

One of my project, is a Li-ion battery based product (2-cells), and I would like to use a battery management IC to solve the charging process management, and the cell balancing.

The questions I came up are the following:

Is the BMS IC make any output when not configured?
What is the process of the board bringing-up on a new design, using this IC on custom PCB?

So the detailed situation is the following:

- I built the reference design, everything looks fine.

- I started to solder the parts, only the NTC-s, and the precharge parts are missing. (the missing of precharge part is designed)

- When I apply the batteries, nothing happens (there is 7.2V on BAT pin) the gate of the DSG , and the CHG fets are low, so I didn't get any output on the pack+.

- But i still not tried to connect the device with SMBus, because I thought, there will be some output power, and my MCU works from this power source (of course regulated), and that's where I would like to configure from.

- Is the bqstudio can connect to any serial device to config the BMS? I do not have a I2C->USB device, but I can manage to connect the I2C via UART->USB and an external MCU's I2C perif.

Any answer would be appreciated.

over 8 years ago

0 ThomasCosby over 8 years ago

TI__Guru 73830 points

The problem could be that that the device is pre-configured for 3S. I would apply 12V from VAC to PACK- until you can communicate to the device and reconfigure it to 2S.

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

Thanks for the fast answer!
Unfortunately I've tried to apply 10V from VAC to PACK- with an external supply, but still nothing happened, there was no output. Is there any chance that the device will reject to give output, until it "thinks", that the 2+ and the 3+ is shorted?
And could you tell me, what are the methods to connect the device to the bqstudio? I still not find any proper description about this.

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

I would use resistor divider cell simulator and setup the EVM for 4S. (You can check the EVM User's Guide for guidance.) Connect 16V to the resistor string and press the WAKE-UP button. See if this helps in getting the gauge to wake-up and communicate.

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

The main problem, that I do not own an EVM, and the PCB is wired to 2 cells, the 3, and 4 is tied to 2+.

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

I see. I will try to find a workaround for you tomorrow.

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

I am very pleased!

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

Zoltan,

I connected cells to Cells 1 and 2 on the EVM and shorted across Cells 3 and 4 at the connector. I verified that the gauge would not power-up. I then applied 12V to the charger (VAC to PGND) on the EVM and the gauge powered up and I was able to reconfigure it to support 2S. The gauge would then power-up without the charger voltage applied.

I would check to make sure that voltage is at the ACP pin on your device when you apply the charger voltage.

Tom

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

I just tried the solution You suggested, but unfortunately the same happens, nothing.When I apply the charger with 12V, ACP and the VCC has voltage in it, but none of the FET-s opened. Is the device should power-up, and should supply power to the external components, if the ACP and VCC pins are high? If it is, I'll replace the BMS IC with another one. Thanks in advance!

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

The FETs can remain open in the scenario that I suggested. The charger voltage will provide power to wake-up the device and allow you to change the series cell configuration. the device may be defective.

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

In that case, I have to config the BMS with an MCU (STM32F4), and I would like to ask you to send me the necessary messages, which I have to send on I2C bus, if you can. Thanks in advance!

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

Now I managed to communicate with the BMS IC on SMBus, with an MCU. I've managed to figure out, that I have to write DA config register, on 0x495d, I have to modify the value from 0x12 to 0x11. I am afraid to brick the device, if I do not use the correct way of doing this. I think the following sequence will do the magic, am I correct?

i2c_start(slave);
i2c_write(slave, 0b00010110); //BMS address to write
i2c_write(slave, 0x44); //command 0x44
i2c_write(slave, 0x03);         //byte count

i2c_write(slave, 0x5d); //data LSB (0x495d)
i2c_write(slave, 0x49); //data MSB
i2c_write(slave, 0x11); //0x11 the value I need
i2c_stop(slave);

If not, please write to me, that how I can write 0x11 to DA_Config register.

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

We are not able to provide support with communicating with the device using 3rd party tools, although the commands will be the same as those presented in the TRM. You should not attempt to configure and run the optimization cycle using 3rd party tools or a uC. You should find a way to tap into the SMBus and use bqStudio and your life will be a lot easier. You can use the uC after development has been completed.

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

I see. The only question I still have, that how can you attach something (not EVM) to the bqstudio? I aint found any options where I can modify the connection device location, or anything like that. Is a well configured COM port can do the task?

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

You will need to use the EV2300 to interface between the gauge and your PC. the EV2300 should have a four wire interface cable and you can cut the connector from one end and solder wires to the SMBus in your module. You will need to disable your uC, because the EV2300 does not support SMBus arbitration.

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

That is the procedure to update SMBus and MAC commands. We have an applications brief on the bq40z50 website that covers data memory programming.

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

The EV2300 is arrived. bqstudio is attached, everything looks cool. CC, NR bits, chemistry are configured, but all of my fets are low. I can toggle dsg fet by chg_fet_toggle button, and when I do it, there is output as expected. How the hell can I "start" the BMS?

0 user4401865 over 8 years ago in reply to user4401865

Intellectual 290 points

Is there any documents which describe step-by-step, that what is the minimal config, which has to be made, to get output from the BMS? I mean, the calibration is not neccessary, but the cell count setting is.

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

The EVM User's Guide is supposed to provide enough information to get started. You should be able to send the FET_EN command and turn the FETs on. You can set the NR bit to 1 to make sure that SYSPRES is not inhibiting the FETs. Some faults will also inhibit them.

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

Can You help me to diagnose the problem? I can toggle the fets manually, but automatically nothing happens. Do I need to seal the device to start working?

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

Zoltan,
The Registers screenshot does not provide any clues as to why the FETs are disabled. The FET_EN flag is set, the PRES flag is set and there are no fault conditions flagged. Could you export an srec file and I will check your configuration on my bench setup to see if this issue is repeatable? You can export an srec from the Firmware screen in bqStudio.
Tom

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

2015.07.02_BMS.srec.zip

I've attached the .srec. Thanks in advance!

0 ThomasCosby over 8 years ago in reply to user4401865

TI__Guru 73830 points

Zoltan,

The device has a hidden register that can disable the FETs and it had been overwritten. I am not sure how it got over written, but you mentioned that you had been writing to the flash, so maybe it was written by mistake. I fixed that register and also made a few other parameter changes in the attached srec file to support a 2S configuration.

I changed the:

Term Voltage from 9000 to 6000

Sleep Current from 0 to 10

Minimum Voltage Output from 6294 to 4214

Voltage Resolution from 25 to 16

Tom

2015.07.02_BMS modifiedTI.srec

0 user4401865 over 8 years ago in reply to ThomasCosby

Intellectual 290 points

Thank You very much, now It's working fine. But how it is possible to write a hidden register? There is an auth module, why hidden registers are writeable by default?
But I'm sure, I owe you a beer.

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bq40z60 bring-up in custom hardware