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BQ40Z50: SBS ManufacturerAccess()通信疑问

Part Number: BQ40Z50
Other Parts Discussed in Thread: EV2400

  我这边尝试去用SMBUS和BQ40Z50通信,但发现有部分通信格式和TRM描述不符合。例如读取芯片的chem-id,根据BQ40Z50-R5 TRM page 111的描述,

host应该是发送

0x16(器件地址)+0x44(寄存器地址)+06+00(CHEM_ID对应的命令)+CRC

回读的值应该是0x16(器件地址)+0x44(寄存器地址)+0X17(器件地址+读)+06+00(CHEM_ID对应的命令)+0x10+0x12(CHEM-ID)=CRC。

  实际逻辑分析仪抓取EV2400和BQ40Z50通信时发现,实际host发送的是

 0x16(器件地址)+0x44(寄存器地址)+0x02+06+00(CHEM_ID对应的命令)+CRC

回读的值是

0x16(器件地址)+0x44(寄存器地址)+0X17(器件地址+读)+0x04+06+00(CHEM_ID对应的命令)+0x10+0x12(CHEM-ID)=CRC。

请问这里多的0x02和0x04是什么,是指后续的数据长度吗?