BQ76940: BQ76940 SDA cannot respond to register signals.

GeneralReturnType BqIf_SetDeviceByte(uByte addr,uByte data)
{
uByte i = 0;
uByte wr_crc;
uByte calc_crc_data[3];

__DI();// Off interrupt

calc_crc_data[0] = BQ76940_WR;
calc_crc_data[1] = addr;
calc_crc_data[2] = data;

wr_crc = crc8_check(calc_crc_data, 3)// calculate CRC

// write 3 times until write ok
for(i = 0; i < 3; i++)
{
BqIf_IICStart();//
BqIf_WriteByte(BQ76940_WR); 
if(BQIF_ERR_OK != BqIf_IICAckDevice())
{
BqIf_IICStop();
continue;
}
BqIf_WriteByte(addr);
if(BQIF_ERR_OK != BqIf_IICAckDevice())
{
BqIf_IICStop();
continue;
}
BqIf_WriteByte(data);
if(BQIF_ERR_OK != BqIf_IICAckDevice())
{
BqIf_IICStop();
continue;
}
BqIf_WriteByte(wr_crc);
if(BQIF_ERR_OK != BqIf_IICAckDevice())
{
BqIf_IICStop();
continue;
}
BqIf_IICStop();
break;
}
__EI();
if(i >= 3)
{
return BQIF_ERR_WR;
}
return BQIF_ERR_OK;

}

When reading, the read instruction has ACK feedback, but I originally wanted to read the 0x05 address. SDA was changed by BQ low, and there was no ACK response. If the write is correct, the timing should not be wrong, as shown in the figure below and Code, code is a simple test code, only send read instructions and register addresses

__DI();
BqIf_IICStart();
BqIf_WriteByte(0x11);

if(BQIF_ERR_OK != BqIf_IICAckDevice())
{

}

BqIf_WriteByte(0x05);

if(BQIF_ERR_OK != BqIf_IICAckDevice())
{
BqIf_IICStop();
}
else
{
BqIf_IICStop();
}

__EI();

The timing diagram is as follows

Waiting for your reply.

Thanks

Star