Hi David,

Thanks for your response. I am new to this aspect of battery management so it's taking me some time to understand it. I will return to this thread later. For now, I am having some issues just sending hex commands using the GUI. I will start a new thread regarding this.

Best Regards,

Muthu

Hi David,

I have a good understanding of Hex commands now and I can communicate effectively with the board using the GUI. Now I'm trying to do the same with an Arduino Mega. I have connected the 5V, GND, TX1, RX1 pins to the correct pins on the EVM. The EVM is connected to a string of 13 li-ion cells in series.

The Hex message I want to send is: 81 00 22 20 28 84 , which according to the SLVA617A document is a request for the voltage and temp aux measurements.

I put together a simple Arduino code (attached) but I'm getting no response on the serial monitor.

1) When using a microcontroller, you are basically sending a request to the EVM and displaying the response from the EVM board. Do you have to send a WAKEUP signal on the WAKE pin first?

2) Is there further documentation about the example code? The SLVA635 document only mentions how to open the code on CCS. I have done this, but how do I get started with this? I cannot find an intro guide or any explanation in any of the folders of the example code on CCS.

Best Regards,

Krishna

byte message[] = {0x81, 0x00, 0x22, 0x20, 0x28, 0x84};

void setup() {
  Serial.begin(9600);            // to the laptop
  Serial1.begin(250000);     // to the EVM board   
}

void loop() {
 
  Serial1.write(message,sizeof(message));        // send message to  EVM board
       while(Serial1.available() > 0){                            // if there's a response from the EVM board.....
       Serial.print(Serial1.read());                                // ......display it on the arduino serial monitor
    }
  delay(5000);
}

Hi David,

I now understand how to turn the EVM board on using the Arduino Mega. I have the WAKEUP, nFault, TX, RX, 5V and GND pins of the EVM board connected to the relevant pins on the Arduino. When I read from the EVM using Serial1.read() on the Arduino, I receive the response "-1" or "FFFFFFFF" if I type Serial1.read(), HEX.

Even if I send any HEX commands to the board, and then read from the board, I get the same response. Do I need to import the libraries from the CCS example code into my Arduino shell? I have not been able to find a clear introductory documentation to the example code.

My main objective here is to be able to sample cell voltages and temperatures when I input the request. Otherwise, I want the board to tell me if there is a UV, OV or high TEMP fault, so that the Arduino can then act to cut out the connection to the charger or load.

Best Regards,

Krishna

Hi David,

Thank you for your help. I have a better understanding of the system now. I can send messages from the Arduino Mega to the board and receive a response.

I can send the message:

94 00 03 1F FF FF 00 E7 DD ...(select 13 cells and 8 AUX temp sensors)

...81 00 02 20 28 84 (request cell and AUX values)

to receive a string of HEX values for the voltages of my 13 cells and the 8 temperature sensors. I have my TX/RX ports connected to the Serial comms (RX3/TX3 respectively) on my Arduino Mega. The WAKEUP and nFAULT pins are connected to two different digital pins on the Mega.

How do I read error messages? Is the nFAULT pin supposed to turn HIGH when a fault is detected? I am sending the following message:

92 00 90 66 66 12 7A               (setting the OVERVOLTAGE fault to 2 V as a test)

All my cells are currently at 3 V. But nFAULT is not turning HIGH and the BQ's TX pin is not transmitting a OV fault message (how would this look like as a HEX string?)

Best Regards,

Krishna 

Hi David,

Could I please get some help regarding error messages (detailed in my previous message)? 

This is the last thing I need to configure. Then I can use the Arduino to turn various switches off to prevent overcharge/overdischarge.

Regards,

Krishna

Both your examples in the last message show (no fault). Can you clarify this?

Do you mean:

Fault_N (no fault) is true, pin output is a logical 1 or 5V

Fault_N (fault detected) is false, pin output is a logical 0 or 0V. 

Hi Muthu,

You are correct. 

The (no Fault) was meant  to  just be a clarification for what the Fault_N pin represents. I apologize for  the poor wording.

You're interpretation is correct, though.

Hi David,

Thank you for your patience so far, I think I'm almost there. I am still not able to get the right response from the nFAULT pin. This is the message I'm sending:

{0x91, 0x00, 0x3D, 0x00, 0x3C, 0x6C,                     //  2.2.1   Configure the initial sampling delay

 0x91, 0x00, 0x3E, 0xBC, 0x3D, 0x2D,                    //  2.2.2   Configure voltage and internal sample period

 0x91, 0x00, 0x07, 0x00, 0x2E, 0xCC,                     //  2.2.3   Configure oversampling rate

 0x91, 0x00, 0x51, 0x38, 0x10, 0xBE,                      //  2.2.4   Clear and check faults - system status register fault flags

 0x92, 0x00, 0x52, 0xFF, 0xC0, 0x59, 0xAC,              //          Clear and check faults - summary flags

 0x94, 0x00, 0x03, 0x1F, 0xFF, 0xFF, 0x00, 0xE7, 0xDD,  //  2.2.5   Select number of cells and channels on a single module

 0x92, 0x00, 0x90, 0x66, 0x66, 0x12, 0x7A};                       //  2.2.6   Set OV to 2 V

 0x81, 0x00, 0x02, 0x20, 0x28, 0x84};                   //          Request voltage and aux temp data

I set the OV limit to 2 V as a test. All my cells are at 3.5 V.

According to our previous conversation, the nFAULT pin should be HIGH by default. But after I send this message, nFAULT should turn LOW as there is an OV fault.

However, nFAULT is on LOW the whole time. This seems to be the default setting. What am I missing?

Regards,

Krishna