BQ76920: The battery voltage can be read, but the configuration register can not be read, may I ask if the chip can only read data register.

?? ?

Part Number: BQ76920

As shown in the figure，SYS_CTRL1 register can be written correctly, but it cannot be read correctly. The data register can read the battery voltage normally. Therefore, whether the bit configuration register cannot be read or needs to be unprotected when reading.

2 个月前

0 Eirwen 2 个月前

TI__Genius 9335 points

You should be able to read from 0x04 with no problems. Do you have an EVM to test on? Have you looked at our example code for reference?

0 ?? ? 2 个月前回复 Eirwen

Prodigy 10 points

Thank you for your answer. Could you please provide the address or source file of the code? I can't find it on the official website

0 Eirwen 2 个月前回复 ?? ?

TI__Genius 9335 points

You can find it in the device's product page:

0 G_Zhao 2 个月前回复 Eirwen

Prodigy 20 points

hello, im his colleague，i can describe this problem to you deeply.
we dont use TI CPU like msp430 but another chip.
This is our IIC transfomation function

rt_uint8_t
BQ76920_ReadOneByte (rt_uint16_t ADDR)
{
  rt_uint8_t temp = 0;
  BQI2C_Start ();
  BQI2C_SendByte (0x10);
  BQI2C_ReceiveAck ();
  BQI2C_SendByte (ADDR);
  BQI2C_ReceiveAck ();
  BQI2C_Start ();
  BQI2C_SendByte (0x11);
  BQI2C_ReceiveAck ();
  temp = BQI2C_ReceiveByte ();
  BQI2C_SendAck (1);
  BQI2C_Stop ();
  return temp;
}

We are going to use this in our status detecting functions

unsigned char BMS_sta, DSG_STA, CHG_STA, DSG_STA_FLAG, CHG_STA_FLAG;
void
BMS_STA (void)
{
  BMS_sta = BQ76920_ReadOneByte (SYS_CTRL2);
  DSG_STA = BMS_sta & 0x02;
  CHG_STA = BMS_sta & 0x01;
}

But we found that when BQ76920_ReadOneByte is working, the register address can be sent normally, but the register value received by the function is 0x00, thats the problem.

By the way, our WriteOneByte function can work normally, heres the code.

void
BQ76920_WriteOneByte (rt_uint16_t ADDR, rt_uint16_t DataToWrite)
{
  BQI2C_Start ();
  BQI2C_SendByte (0x10);
  BQI2C_ReceiveAck ();
  BQI2C_SendByte (ADDR);
  BQI2C_ReceiveAck ();
  BQI2C_SendByte (DataToWrite); 
  BQI2C_ReceiveAck ();
  BQI2C_Stop ();
  rt_thread_mdelay (10);
}

We need help, and if you want some other information please reply, thank you:

0 Eirwen 2 个月前回复 G_Zhao

TI__Genius 9335 points

Are they sending CRC? This device requires CRC to communicate properly. The TI sample code should serve as an example for their own code, as it implements the CRC function in it.

0 G_Zhao 2 个月前回复 Eirwen

Prodigy 20 points

First in this type CRC is optional, and we try to send CRC but the problem still exists.

0 Eirwen 2 个月前回复 G_Zhao

TI__Genius 9335 points

CRC is not optional in this device when writing. You require CRC to write.

See Question 6.5 Can I use the CRC part without CRC? of the bq76920, bq76930, bq76940 AFE FAQ.

I would advice that you test using an EVM to ensure it all works properly. The sample code should function as an example to implement in your own code.

电源管理

电源管理论坛

BQ76920: The battery voltage can be read, but the configuration register can not be read, may I ask if the chip can only read data register.