SLUUC54C February 2020 – March 2024 BQ27Z558 , BQ27Z561 , BQ27Z561-R2
The gauge supports the standard I2C read, incremental read, one-byte write, quick read, and functions. The 7-bit device address (ADDR) is the most significant 7 bits of the hex address and is fixed as 1010101, or 0x55. The 8-bit device address is therefore 0xAA or 0xAB for write or read, respectively.
(S = Start, Sr = Repeated Start, A = Acknowledge, N = No Acknowledge, and P = Stop)
The quick read returns data at the address indicated by the address pointer. The address pointer, a register internal to the I2C communication engine, increments when data is acknowledged by the fuel gauge or the I2C master. Quick writes function in the same way and are a convenient means of sending multiple bytes to consecutive command locations (such as two-byte commands that require two bytes of data).
Attempt to write a read-only address (NACK after data sent by master):
Attempt to read an address above 0x7F (NACK command):
Attempt at incremental writes (NACK all extra data bytes sent):
Incremental read at the maximum allowed read address: