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BQ77PL900EVM-001: BQ77PL900 Evaluation Software Can't Connect to EVM

Alex Mazur1
Prodigy 95 points
Part Number: BQ77PL900EVM-001
Other Parts Discussed in Thread: BQ77PL900, EV2400, BQ76930EVM, BQ76930

Hello,

I am having issues with getting the BQ77PL900 EVM to connect to the evaluation software. I am using the EV2400, which should work with the BQ77PL900 (this is stated in the EVM user guide). However, when I run the evaluation software, I get an error message stating that there is an I2C communication error. I have verified that my PC can connect to the EV2400 because I am able to run the firmware update tool. I have also made sure to install the support components for the EV2400 before connecting the hardware to my computer.

Any help to resolve this would be appreciated.

Regards,

Alex

  • 0
    TI__Genius 10830 points

    Hi Alex,
    Thank you for your interest in BQ77PL900. 
    One of our engineers will come back to you once we are back at the office.

  • 0 in reply to David Hien
    TI__Guru 54715 points

    Hi Alex,

    The BQ77PL900EVM-001 is an older product as you might have noticed and systems have evolved over time.  As noted in the EVM user guide http://www.ti.com/lit/sluu324 operation of the evaluation software needs:

    1. The BQ77PL900 evaluation software
    2. EV2400
    3. Support components (drivers), but they must be updated with the EVSW such as the one noted in section 5.3 of the EVM user guide.

    If you don't have the EV2400 attached or have the updated support components you see a USB error box:

    But you mention I2C error.  If the software is finding the adapter but not the IC it shows the register screen scanning the registers with an I2C error shown in the right top such as this.

    In this case check that the 4 pin cable is connected to the I2C connector.  Check that the EVM has power, cell voltages should be simulated as needed and check that VREG1 and VREG2 are present, you might confirm the PACK+ voltage is above about 8V.  Be sure there is a VL selection (shunt is in place) at J10.  Check that the I2C signals reach the EVM, they are available on J13.

    One of these should fix the issue.

  • 0 in reply to WM5295
    Prodigy 95 points

    I have confirmed that the issue is with the I2C communication between the EVM2400 and the BQ77PL900EVM. The I2C data lines are pulled up to 3.3V, and I do not see any data being sent/received. I confirmed that the EVM2400 is connected to my PC.

    I have the the BQ77PL900 configured as follows:

    1) 7 Cell configuration (CNF2 = 0, CNF1 = 1, CNF0 = 1). I made sure the short 10P, 9P, 8P, and 7P together. I am using 7 resistors and a power supply (set to 27.4V) to simulate a battery. The voltage drop across each resistor is approximately 4V.

    2) 3.3V logic level is selected

    3) Pre-charge FET is not being used.

    4) VREG1 = 5V, VREG2 = 3.3V

    5) Pack voltage is at 27.4V; I have tried using a different power supply across PACK+ and PACK- to wake up the IC, as suggested by the user guide.

    I still get "I2C Comm Status: Error". Would moving to the BQ76930EVM help to solve this issue? I am considering that as an option since the BQ77PL900 is an older and outdated chip, but I am concerned that I will run into the same issue I am seeing now.

    Thank you for your help thus far, I look forward to hearing back from you soon.

    Regards,

    Alex

  • 0 in reply to Alex Mazur1
    TI__Guru 54715 points

    Hi Alex,

    Did you install the EVSW noted in the BQ77PL900EVM-001 user guide?  Also be sure you are connected to the I2C connector of the EV2400.

    The BQ76930 will support 7 cells, it is a slightly different function in that it can not operate stand alone and must always have a MCU for configuration, enabling FETs and fault recovery.  The BQ77PL900 may be preferred for some applications. 

    The BQ76930 evaluation software uses different drivers.  Since it also talks to I2C you can set the address and talk to the BQ77PL900 using the PRO window or single register portion at the top of the window.  Certainly you do not get the decoded structure of the BQ77PL900 GUI but you can confirm that you can talk to the device.  Remember that the address is shifted when it appears on the bus, there is often a confusion of the 7 bit and 8 bit addresses.