BQ76972: Data Memory Access function issue

Ashley Ma

Part Number: BQ76972

Tool/software:

Customer: HUIZHOU EVE

Issue:

About the Data Memory Access function of BQ76972, when using the 0x9239 command and the 0x0001 command to read data, has encountered an anomaly in data retrieval, and I would like to confirm this.

Customer question:

For the readback of 4 bytes of data 0x93 0x92 0x12 0x00, there are two issues: one is that the command is incorrect (it should be 0x01 0x00), and the other is that the CRC field is not present.

Detailed description of the issue:

First, enter CFG MODE, and use the 0x9239 Comn Type command to configure the communication mode to 0x12, which corresponds to IIC Fast with CRC mode, and then exit CFG MODE.

Then the code uses the mode with CRC to read the data corresponding to 0x9239 and 0x0001.

The 0x0001 command fails to read the device number.

After capturing the IIC bus data, it was observed that when 0x0001 was sent to 0x3E, it carried a CRC field, and 76972 responded with an ACK, indicating that 76972 successfully received the 0x0001 command and that the CRC for 76972 was enabled. As shown in the figure below:

Subsequently, the code performs a readback of 0x0001 at 0x3E. At this point, the code reads 4 bytes from 0x3E (CRC is enabled) and finds that the previous few reads returned four 0xFF values, while the subsequent reads consistently returned the 4 bytes 0x93 0x

92 0x12 0x00. As shown in the figure below:

The readback of the 0x9239 command is the same in data and phenomenon as the readback of the 0x0001 command.