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BQ27Z561-R2: Communications problems with bq27z561-R2 and EV2300

Part Number: BQ27Z561-R2
Other Parts Discussed in Thread: BQSTUDIO, , BQ34Z100, BQ27Z561, EV2400

Hello,

I am experiencing difficulty while trying to communicate with an bq27z561-R2 with bqStudio (or battery management studio?) and an EV2300 using I²C.

It appears that every other access returns a value, but doesn't have a valid I²C stop condition. This causes the next access to fail. This is visible in bqStudio as well: Every second value is shown, but the others are not, and the program displays a lot of NACKs. The device detection on starting the software fails as well, and I selected the device manually. However, in bqStudio I can hit the buttons for e.g. FirmwareRev and valid values are displayed...

I tried with a couple of EV2300 with firmware 3.1m, to no avail. I also tried reading out battery packs with different ICs (bq27742, bq34z100) with the same PC, bqStudio, and EV2300. This worked as expected.

The datasheets for these different ICs don't give me a clue about different I²C requirements, but I may have missed something.

Also, I tried to set the bq27z561 to slow (100kHz) I²C mode. Yes, DF writing / reading appeared to work, although the bqStudio still indicated intermediate NACKs. This setting didn't change anything, though.

I will try to add some oscilloscope screenshots today.

Thanks in advance for any help!

  • Hello Jorg,

    Since the EV2300 is an older device and not supported I would recommend you use the EV2400, the firmware for the EV2400 will be more up to date than the EV2300 which may have bugs when communicating with newer gauges.

    Sincerely,

    Wyatt Keller