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BQ76PL455EVM: Issue with Hardware connection using TTL-UART connector

Part Number: BQ76PL455EVM
Other Parts Discussed in Thread: MAX232

Hi,

I am using the TI development board. It was working fine few hours back until i tried connecting a different hardware to talk using UART port.

So the board is powered from the cells. I am simulating 14 cells using resistors. Input Voltage is 52V supply and 0.08 A current which creates 3.7 V of reading across each resistor. But as soon as i connect the USB to laptop ,the LED on the board turns green but the input voltgae drops down to 30V. I tried using different laptops but results were same. I am now not able to open the GUI provided by TI( error says cannto open COM port).  I am thinking that maybe i blew up the board connecting a RS232 cable to the TI board( i was trying to mimic the TTL-UART connector provided by TI).

I wanted to know if there are any clamps on Rx and Tx of UART on TI board. 

Also , is the board reparable considering this situation?

  • Hi Avesh,

    Did you connect VSENSE15, VSENSE16 and TOP to the 14th cell as well?

    It sounds like you have shorted something to GND, and your power supply is limiting the current.

    I would ask to make sure BOTH actuators of the switch are set to "Single", and that the metal pins of the FTDI cable are facing up when plugged into the UART header.

    Take a multi meter and look around for voltages that are incorrect or blown FETs/Diodes, or even shorts.

    The EVM schematic is located here: www.ti.com/.../TIDA-00717 .it should be helpful for debugging.

    EDIT: Yes, it is most likely repairable if you  are  handy with a soldering iron/heat gun. Components can always be replaced.  If you blew a trace  on the board, then you are in trouble.

  • Hello,

    Thank you for your response. First of all  I cannot open the TI GUI.  COM port cannot be connected.

    So i made a connector usign USB-RS232 conveter, max 232 converter and a serial port utility software to send signals. I verified the UART communication by connecting the command and feedback bits to a scope. It worked fine. Then i checked the following things:

    1) check all the voltage readings across the diodes. Yes, i shorted the one which i was not using. Moreover i know it is right because it worked before.

    2) Check the voltage level of wake-up signal, Vcc ,Rx,Tx and ground w.r.t the TI ground. They were all zero. Checked the same signals with 5V signal supplied externally( coming from Max232 converter) and wake-up connected to ground, I can see the yellow LED turned ON, Vcc reads 5 V, Rx and Tx pins both read 5 v. However, the supply voltage goes from 52 to 40 volts. and the current max-out to the set current value of 0.084 Amps. Now if i connect the serial port to laptop , the voltage and current remains 40 and 0.084.  If i increase the set current to 0.090, the voltage increases to 44 v from 40 v.

    3) I also tried sending a command to TI board using a USB-RS232 converter, max 232 converter and a serial communication utility software( verified before). I can see a command on RX pin of TI board, but there is nothing on Tx pin. ( voltage drops to ground on Rx pin when message is received).

    I am not sure what is going on. However if it is repairable, is there a way i can get it repaired at TI?