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CCS/EM1402EVM: Not able to balance through EM1402EVM for 8S config

Vishal Mali88
Prodigy 40 points
Part Number: EM1402EVM
Other Parts Discussed in Thread: BQ76PL455A, BQ76PL455A-Q1

Tool/software: Code Composer Studio

Hi, I have recently bought EM1402EVM and trying to balance 8 cells in series(18650), boards are not stacked, just one board.I am newbie in this. I am connecting it through hercules launchpad. I have gone through users guide to do connections, just confused about 16S cable where to connect(I have shorted all remaining balancing cables after 8 to 8th cable). and another thing Do I have to change all values in Example code for 8 cells? Thanks in advance.

  • 0
    TI__Genius 11480 points
    Hi Vishal,

    I will answer your second question first: Yes, you must change the example code for 8 cells. That means, with the PL455 you must change the NCHAN to 8 cells, the CHANNELS register, etc. When writing the API for the SPI commands to the EMB1428, you must also consider that you are only using 8 cells. Please note that the bq76pl455a example code does not include the info for the active balancing chipset.... only passive balancing through the EQ pins of the pl455.

    For the cable, where is your confusion? If you have all higher sense lines connected to the top most cell, it should be ok.
  • 0 in reply to David Wiest Jr
    Prodigy 40 points

    Hi, 

    About cable, I was not sure where to connect 16S (I have connected BAT16 to last cell though).

    and I searched for the same problem statements in ti forum, and I think I have missed few steps in connections like

    I went through schematic, U2's 38 and 39 pins are connected to R8 and R9 and further connection goes to SCI1_RX and SCI1_TX resp. So Can I connect J4-1 and J4-2 to SCI1_RX and TX? 

  • 0 in reply to David Wiest Jr
    Prodigy 40 points
    Hi David,
    I have made all the necessary modification to launchpad and as well as code, I have connected all the 8 connection for emulating 2nd uart port between EVM and Launchpad mentioned in www.ti.com/lit/ug/tidubi0/tidubi0.pdf .
    Then debugged the code in CCS, still not able to balance cells.

    One more thing, can this setup be used using BQ76PL455A-Q1 gui, I tried but I got "Unable to open COM port error".

    Thanks in advance,
    Vishal M
  • 0 in reply to Vishal Mali88
    TI__Genius 11480 points
    Hi Vishal,

    Thanks for all of the information...

    To answer your first post, yes you must physically remove (unsolder) R8 and R9 from the TMS570 and then make the other connections.

    You should be able to use the bq76pl455A-Q1 gui, as it is used in this document. If it is not opening, that means that the PC has not established a connection through the MCU.

    I think, if you are following the TIDM, then the GUI needs to be communicating for balancing to work.
  • 0 in reply to David Wiest Jr
    Prodigy 40 points
    Hi David,
    I was trying to balance 16S cells this time. So I assume there is no need to change code. All connections are done perfectly. But I still have no luck with GUI(same error, Unable to open COM port).
    So I just kept CCS debugger running for an hour, the result I have got is as follows:
    1) All cells are started to drop their voltage. ( They kept discharging without sending charge to external battery source)
    2) And BQ76PL455A-Q1 and balancing ICs(EMB....) started to heat.

    Since I dont have any means to debug code (to know flow of execution) I am not able to get the exact problem here.

    So GUI would be the lots of help, how can I resolve this "Unable to open COM port error" ? And is there any other means to debug the code?
    Thanks.
  • 0 in reply to Vishal Mali88
    TI__Genius 11480 points
    Hi Vishal,

    could you doulble check which FTDI driver you are using, and that it matches your operating system? I have seen this cause problems with the GUI before.

    Could i ask you to check the wiring on your cable harness to the cells? It sounds like something is connected in such a way that it is causing the IC's to consume a significant amount of current. That could also explain why the GUI can't open - if it isn't talking with the pl455 because it is damaged, etc, then the GUI doesn't launch (one of my chief complaints about our GUI)