BQ76952EVM: powering up BQ76952evm using a microcontroller

Hi,

Today and tomorrow (Nov. 28-29) are U.S. holidays. The team will be back in office on Monday, and will get back to you then.

Thank you for your patience.

Regards,

Max Verboncoeur

Hello Criton,

Thank you for your patience.

What is the DC Power Supply Voltage you are supplying? Can you double check the REG1 pin with a multimeter to make sure it’s outputting 3.3V? Also, can you check the voltage at TP10/REG18 as well?

Best Regards,
Alexis

Hi Alexis,

Many thanks for getting in touch. My setup is as shown in the attached figure below. The MCU is esp32 from which I connect the 3V3 pin to REG1 pin on the BQ76952 EVAL board and GND pin of the ESP to VSS on the eval board. ESP is connected to my PC. My DC power supply is set to 30V which is connected to the cell 16 and VSS of the eval board. 

TP10 gives me 1.8V when switch on the DC power supply which is set to 30V. REG 1 is 0V.

Many thanks,
Criton


 

Hello Criton,

I think your image didn’t get attached. Do you mind sending it again?

If REG18/TP10 is reading 1.8V, that means the part is ON, or it would read 0V. The pin REG1 is not seeing 3.3V from the MCU. Can you double check if the MCU is outputting 3.3V? 

Best Regards,
Alexis

Hi Alexis,

Thank you for getting in touch. The MCU is outputting 3.3V. I just checked it. Correct me if I am wrong if the BQ76952evm receives the power from esp it should light up the LEDs on the evm board right?. I dont see it.

The image is same as the one in the User guide.

Hi Alexis Many thanks for getting back. Does that mean you cannot power the BQ76952 eval using a Microcontroller? Also the shunts are for I2C right?

Kind regards,
Criton

Hello Criton,

Can you clarify what you mean when you say, ‘power the BQ76952 EVM with a microcontroller’? Are you asking if a MCU can power the entire evaluation board? If you want to externally supply REGIN to power the LDOs (REG1/REG2), that is possible. 

The shunts are for I2C.

Best Regards,
Alexis

Hi Alexis,

Alexis_H said:

Can you clarify what you mean when you say, ‘power the BQ76952 EVM with a microcontroller’? Are you asking if a MCU can power the entire evaluation board?

YES.

Kind regards,
Criton

Hello Criton,

We have received your request and will work to answer it as soon as possible. 

Our normal support team is OOO and will be returning 12/10 to help with any ongoing inquiry. 

We appreciate your patience and understanding.

Best, 

-Luis Torres 

Hi Alexis,

Many thanks for getting in touch.

I think the way I explained the issue is not quite understandable. The question is; I have connected my 16 cells on the BQ76952 to a DC supply with 60V and 2.5 A and when I connect BQ76952evm to the PC directly the evm turns on and on opening the BQstudio it shows the I2C adress as 0x10. 

I tried to read the I2C address of the bq76952evm using esp32 by connecting to SDA and SCL pins at J17 on the evm and uploaded a code to the ESP which detects the I2C devices connected to it. However it did not detect any I2C device connected to it. However when I connected the esp32 to the SDA and SCL pins and powered the BQ76952 EVM using the usb port on the evm it detected two I2C devices connected to esp32 at 0x08 and 0x48 (without connecting the shunts for pull ups). Now when I connected the pull-up shunts it gives me a bunch of I2C device. Could you please explain what I might be doing wrong.

I have attached the code snippet that I use to detect the I2C address.

Many thanks and Seasons' greetings,
Criton

 

#include <Wire.h>


void setup()
{
  Wire.begin();

  Serial.begin(9600);
  while (!Serial);             
  Serial.println("\nI2C Scanner");
}


void loop()
{
  byte error, address;
  int nDevices;

  Serial.println("Scanning...");

  nDevices = 0;
  for(address = 1; address < 127; address++ ) 
  {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0)
    {
      Serial.print("I2C device found at address 0x");
      if (address<16) 
        Serial.print("0");
      Serial.print(address,HEX);
      Serial.println("  !");

      nDevices++;
    }
    else if (error==4) 
    {
      Serial.print("Unknow error at address 0x");
      if (address<16) 
        Serial.print("0");
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");

  delay(5000);           // wait 5 seconds for next scan
}

Hello Criton,

Thanks for clarifying what you are asking for. The default address of the bq769x2 family is explained here. Something to keep in mind as well is the bq76952 initially powers up by default in 400kHz I2C mode.  

There is a chance your code is not correctly detecting for I2C addresses. Is your address in HEX?

Also, have you tried communicating directly with the address given (without trying to detect for it first) to see if that works? 

Do you also mind sharing a logic analyzer file at the SDA/SCL pins when it’s at J17 of the EVM without the USB port connected? This will also show if the host is trying to communicate correctly as well.

Another useful resource is the sample code we have.

Best Regards,
Alexis

Hi Alexis,

Many thanks for your response.

Alexis_H said:

There is a chance your code is not correctly detecting for I2C addresses. Is your address in HEX?

Now I can confirm that the I2C address that it was giving is correct as the 0X10 is the 8 bit address where the least significant bit is the read/write bit. The 7-bit addressing corresponds to 0x08 which the serial monitor was printing out.

Alexis_H said:

Do you also mind sharing a logic analyzer file at the SDA/SCL pins when it’s at J17 of the EVM without the USB port connected? This will also show if the host is trying to communicate correctly as well.

Do you mean to have the BQ76952evm connected to the battery pack (supplied by the DC power supply 60V) ? If that's the case there is no signal on the scope. I can only see the BQ76952evm work when it is connected to USB port.

Many thanks and Seasons greetings,
Criton

Hello Criton,

Glad that was able to help.

Please try using a logic analyzer at TP39 and TP40 and using a logic analyzer at the J17 connectors in this scenario:
1. The EVM is connected to the 'battery pack' (supplied by the DC power supply)
2. Without the connection to the USB port
3. With the shunts connected to J15 and J18
4. MCU connected to J17 SCL/SDA lines

Could you share a picture of this setup as well?

Also, is the MCU connected to the same GND as the EVM?

Best Regards,
Alexis