BQ27441-G1: Setting Capacity and Displaying Correct Values

Hello Ashish, 

How are you attempting to write the battery capacity, can you provide me with the steps you have taken? Are you using bqStudio to read and write to the gauge? Can you provide me with the gg file for this? 

Regards, 

Jonny. 

Hi,

Currently i am interfacing this IC with our embedded Linux board, i have took reference from the Spark-fun library but changed all the low level interface according to my Linux board. This spark-fun library follows all step which are mention in bq27441-TRM page no 14.

Note : I am not using bqStudio.

below is the steps i wrote for fuel gauge setting.

void config_gauge()
{
  if (itporFlag())
  {
    setCapacity((uint16_t)bmsconfig.designCapacity);
    delay(2000);
    setDesignEnergy(bmsconfig.designCapacity * 3.7f);
    delay(2000);
    setTerminateVoltage(bmsconfig.terminalVoltage);
    delay(2000);
    setTaperRate(bmsconfig.designCapacity / (.01 * 100));

    printf("MY Desired Full Design_capacity: %d mAh\n", bmsconfig.designCapacity);
    printf("MYFull Design_capacity: %d mAh\n", capacity(DESIGN));
  }
}

And bellow is the low level code.

int16_t i2cReadBytes(uint8_t subAddress, uint8_t *dest, uint8_t count)
{
	int16_t timeout = BQ72441_I2C_TIMEOUT;
	I2cSendData(BQ72441_I2C_ADDRESS, &subAddress, 1);

	I2cReadData(BQ72441_I2C_ADDRESS, dest, count);

	return timeout;
}

void I2cSendData(uint8_t addr, uint8_t *data, uint8_t len)
{
	if (ioctl(deviceDescriptor, I2C_SLAVE, addr))
		syslog(LOG_USER | LOG_INFO, "I2cSendData_device : IOCTL Problem \n");

	write(deviceDescriptor, data, len);

}

/* This function reads data from the I2C device*/
void I2cReadData(uint8_t addr, uint8_t *data, uint8_t len)
{
	if (ioctl(deviceDescriptor, I2C_SLAVE, addr))
		syslog(LOG_USER | LOG_INFO, "I2cReadData_device : IOCTL Problem \n");

	read(deviceDescriptor, data, len);
}

// // Write a specified number of bytes over I2C to a given subAddress
uint16_t i2cWriteBytes(uint8_t subAddress, uint8_t *src, uint8_t count)
{
	uint8_t buf[3];
	buf[0] = subAddress;
	buf[1] = src[0];
	buf[2] = src[1];

	I2cSendData1(BQ72441_I2C_ADDRESS, buf, 3);
	delay(1); //in ms

	return true;
}

Hello Ashish, 

Please ensure that you are sending the SET_CFGUPDATE subcommand before attempting to change each parameter in the gauge. If you do not do this, then the gauge will not allow you to write new values. 

Regards, 

Jonny. 

Hi Jonny,

I've ensured that the SET_CFGUPDATE sub command is properly configured before attempting to modify each parameter.Additionally, I've verified whether it successfully updates the state or not.

Below is the code for your reference. Please review:

_Bool setCapacity(uint16_t capacity)
{
	// Write to STATE subclass (82) of BQ27441 extended memory.
	// Offset 0x0A (10)
	// Design capacity is a 2-byte piece of data - MSB first
	// Unit: mAh
	uint8_t capMSB = capacity >> 8;
	uint8_t capLSB = capacity & 0x00FF;
	uint8_t capacityData[2] = {capMSB, capLSB};
	return writeExtendedData(BQ27441_ID_STATE, 10, capacityData, 2);
}

_Bool writeExtendedData(uint8_t classID, uint8_t offset, uint8_t *data, uint8_t len)
{
	if (len > 32)
		return false;

	if (!_userConfigControl)
		enterConfig(false);
	printf("in write extended data\n");
	if (!blockDataControl())	  // // enable block data memory control
		return false;			  // Return false if enable fails
	if (!blockDataClass(classID)) // Write class ID using DataBlockClass()
		return false;

	blockDataOffset(offset / 32); // Write 32-bit block offset (usually 0)
	computeBlockChecksum();		  // Compute checksum going in
	uint8_t oldCsum = blockDataChecksum();
	printf("after checksum data\n");
	//  Write data bytes:
	for (int i = 0; i < len; i++)
	{
		// Write to offset, mod 32 if offset is greater than 32
		// The blockDataOffset above sets the 32-bit block
		writeBlockData((offset % 32) + i, data[i]);
	}
	printf("wroteblock data\n");
	// Write new checksum using BlockDataChecksum (0x60)
	uint8_t newCsum = computeBlockChecksum(); // Compute the new checksum
	writeBlockChecksum(newCsum);

	if (!_userConfigControl)
		exitConfig(true);

	return true;
}
_Bool enterConfig(_Bool userControl)
{
	if (userControl)
		_userConfigControl = true;

	if (sealed())
	{
		_sealFlag = true;
		printf("doing unseal\n");
		unseal(); // Must be unsealed before making changes
	}
	printf("Now in execute control word\n");
	if (executeControlWord(BQ27441_CONTROL_SET_CFGUPDATE))
	{
		int16_t timeout = BQ72441_I2C_TIMEOUT;
		while ((timeout--) && (!(flags() & BQ27441_FLAG_CFGUPMODE)))
		{
			printf("in while loop\n");
			delay1(1);
		}

		if (timeout > 0)
			return true;
	}
	printf("timeout occured\n");
	return false;
}