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BQ34110: I2C communication troubleshooting (EV2400 vs Custom Board)

Lao Hu
Intellectual 790 points
Part Number: BQ34110
Other Parts Discussed in Thread: BQSTUDIO, , EV2400

Hello,

A custom board (based on BQ34110 EVM) is designed and working with EV2400 as expected. Below a simplified diagram showing the signals SCL [yellow] and SDA [blue] during the communication with bqStudio/EV2400.

In other test, the EV2400 is disconnected from the board and the MCU perform as master. In this case, the BQ34110 doesn't show the ACK. Below a simplified diagram including the scope signals in two different I2C implementations: software (or bit-banging) and hardware. 

  • The MCU is powered by 3.4V
  • The pull-up resistor were adjusted and tested with 10K, 3K and 1.5K
  • The board was power off and on during the testing (in case the bq34110 is on halt state, as reported in other situations/post)
  • Below the schematic around the BQ34110
  • The EV2400 is connected to connector J13
  • The MCU is connected to the signals: BAT_INT_SDA and  BAT_INT_SCL 
  • The software I2C implementation was developed in order to simulated similar waveform as the EV2400, specifically, the start and delay after.

Despite the development and tests carried out, the communication still does not work.

Any suggestion is appreciated.

Thanks

  • 0
    TI__Mastermind 42535 points

    Hi Lao,

    This is going to take us a few days to analyze. Your pullup config seems correct. Please allow us until 2019 07 11 to get back to you.

  • 0 in reply to Batt
    Intellectual 790 points

    Hi Batt,

    Just for your information, the custom board have two BQ34110 connected to different I2C buses. In both the situation is similar, not ACK. I noted one IC REG25 is 2.7V and the other is 2.15V. That give you some clue?

    In other hand, I just connected another small board (custom board #2) including only the BQ34110, as show the diagram below.

    Both BQ34110 are connected in the same bus with the microcontroller as mater. In this test case, the new IC is showing ACK (using HW I2C implementation). The schematic of the custom board #2 below:

    I will try to replace the IC in the Custom Board to check functionality. However, it still seem odd that the EV2400 is connecting successfully and the micro controller is missing ACK from the BQ.

    Thanks for any update regarding the revision of this situation.

  • 0 in reply to Lao Hu
    Intellectual 790 points

    Hi Batt,

    By comparing the signals (all the pins) of both cards, the CE pin is low when the micro controller is programmed.

    After disconnect or handling the CE pin, the BQ34110 shows the ACK.

    With this change, the voltage in the REG25 pin (including 1uF capacitor) is the same in both IC and equal to 2.85V. 

    According with the specs, the REG25 voltage range is 2.3V to 2.7V. Any suggestion regarding this voltage is appreciated.

    Thanks

    Julio