BQ78350-R1: Communication issue with bq969x0

kim seongcheon

Prodigy 160 points

Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76930, , BQ78350, BQSTUDIO, TIDA-00792

Hi, I'm kim

there is Communication issue with bq76930.

I use bq76930000. 2.5 regout, crc mode disable.

I can check the status of bq76930 with I2C. on PC.

I want to communicate with bq78350-r1 via SMB on PC.

Communicating with ev2300.

But i can't.

I check regout and sda and scl signals in attach.

Also, a circuit diagram is attached.

Please help me to solve this problem.

TI_PL07_rev190627.pdf Comm issue with BQ78350.pdf

over 5 years ago

0 Matt Sunna over 5 years ago

TI__Guru* 81034 points

Hi Kim,

Do you have pull-up resistors for your I2C lines and your SMBus lines? I didn't see these on the schematic.

Best regards,

Matt

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

Prodigy 160 points

Hi, matt

Thanks for your reply. There are 10k ohm each line. You can find pull-up resistors in schematic.(R30,R31)

2pin Headers will be shorted by jumper.

Kim

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

TI__Guru* 81034 points

How about for the SMBus pins?

Thanks,

Matt

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

Prodigy 160 points

there are R50 and R52.

these are pull-up resistors for SMBus

thanks,

Kim

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

TI__Guru* 81034 points

R50 and R52 are 1M pull-down resistors, right?

Regards,

Matt

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

Prodigy 160 points

Yes, they are.

I set pull-up resistors for SMBus line up. But it didn't work.

there is no signal at SMBus line.

I think bq76930 and bq78350 are in communication with each other.
But there is no communication output from bq78350 to smb line.

Regards,

Kim

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

TI__Guru* 81034 points

Hi Kim,

What value did you place for the pull-up resistors and what voltage did you connect the resistors to?

Matt

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

Prodigy 160 points

Hi, Matt

I connect with regout which is 2.5v.

I placed 10k ohm resistors for pull-up.

Regard

Kim

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

TI__Guru* 81034 points

Okay, that's good. Is your MCU sending commands on the SMBus lines? The BQ78350-R1 will not drive the SMBus lines - it will only respond to host commands. The BQ78350-R1 does drive the I2C communication with the BQ769x0.

Matt

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

Prodigy 160 points

I think bq76930 and bq78350-r1 communicate with each other.

I can see through I2C communication signal.

But, there isn't no signal in SMBus line.

I don't have a MCU.

I planed this schematic for EVM.

I want to communicate with PC via ev2300 for monitering bq76930.

Kim

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

TI__Guru* 81034 points

Hi Kim,

If you have the PC and the EV2300 connected to the SMBus, you should see communication from BQStudio when you execute commands or if you write to or read from the Data Memory screen. If you have the pull-up resistors and you still do not see any activity, then I recommend trying a different PC, maybe update/reinstall BQStudio, or verify your EV2300 is working with a different board (TI EVM).

I assume you are using BQStudio on your PC?

Best regards,

Matt

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

TI__Guru* 81034 points

Hi Kim,

I haven't heard from you in a while. Have you been able to resolve this issue?

Thanks,

Matt

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

Prodigy 160 points

Hi, Matt

I tried several methods for while.

However, I did not solve the problem.

So, I will design a new one by referring to TIDA-00792.

Thank you for the answers.

KIM

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BQ78350-R1: Communication issue with bq969x0