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BQ76PL455EVM: UART communication

Rohan Patwardhan
Intellectual 260 points
Part Number: BQ76PL455EVM

Dear all,

We have been trying to establish communication with BQ76PL455 EVM and microcontroller but to no avail. We tried to check UART communication on putty terminal but to no avail. We have matched the baud rate to 250k as it is the default. The hex command we are sending is 89 00 00 0A 00 DA 83. 

Regards,
Rohan

  • 0
    TI__Genius 11480 points

    Rohan,

    Can you confirm a few things for me...

    1) Cells or >12V supply/resistor ladder is connected

    2) A wakeup pulse is being applied  and the pl455 is waking up (LED should  turn on)

    3) MCU UART logic levels are the same as the pl455 VIO logic levels

    4) Proper pull up resistors are applied on TX/RX

  • 0 in reply to David Wiest Jr
    Intellectual 260 points

    Hi David,

    There are 16 cells connected to EVM module. 

    We are using the UART to USB cable provided by TI to view in UART terminal. Thus when plugged into PC LED is on.

    Regards,
    Rohan

  • 0 in reply to Rohan Patwardhan
    Intellectual 260 points
    Hi David,
    We arr uaing an STM32 microcontroller. The baud rate has been configured to 250k. Vcc of bq evm and stm32 is 3.3V. when stm32 board is powered up using pc D22 automatically lights up, however we have still added a wake up function in our code. We are however not using pull ups on rx and tx. Is there something we are doing wrong
    Regards
    Rohan
  • 0 in reply to Rohan Patwardhan
    Intellectual 260 points
    Hi David,
    We are using STM32 microcontroller. Connections are-
    Wake up to gpio
    Vcc to 3.3V gnd to gnd
    Rx of stm to tx of evm
    Tx of stm to rx of evm
    The d22 led lights up as soon as stm controller receives power from pc.
    We have not pulled up rx or tx. Is there something we are doing wrong?
    Regards,
    Rohan
  • 0 in reply to Rohan Patwardhan
    TI__Genius 11480 points

    Rohan,

    If you do not have pull up resistors on TX/RX, you should add those. Communication will not  be reliable without them.

    If you have further problems, we'll need to  put a scope  on the  TX/RX lines to make sure they look ok, and  a logic analyzer to make sure the right data is being sent. Otherwise debugging  will be  very challenging.