BQ27621-G1_16 Datasheet, PDF (12/26 Pages) Texas Instruments – System-Side Fuel Gauge With Dynamic Voltage Correlation

bq27621-G1
SLUSBB3E – DECEMBER 2013 – REVISED JANUARY 2016
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Host generated
Gauge generated
S ADDR[6:0] 0 A CMD [7:0] A DATA [7:0] A P
S ADDR[6:0] 1 A DATA [7:0]
(a) 1-byte write
(b) quick read
S ADDR[6:0] 0 A CMD [7:0] A Sr ADDR[6:0] 1 A DATA [7:0] N P
(c) 1- byte read
NP
S ADDR[6:0] 0 A
CMD [7:0]
A Sr ADDR[6:0] 1 A
(d) incremental read
DATA [7:0]
A ...
DATA [7:0]
NP
S ADDR[6:0] 0 A CMD[7:0] A DATA [7:0] A DATA [7:0]
(e) incremental write
(S = Start , Sr = Repeated Start , A = Acknowledge , N = No Acknowledge , and P = Stop).
Figure 5. I²C Format
A ... A P
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 whenever data is acknowledged by the fuel gauge or the
I²C master. The quick writes function in the same manner and are a convenient means of sending multiple bytes
to consecutive command locations (such as two-byte commands that require two bytes of data).
The following command sequences are not supported:
Figure 6. Attempt To Write a Read-only Address (Nack After Data Sent By Master)
Figure 7. Attempt To Read an Address Above 0x6B (Nack Command)
8.5.3.2 I²C Time Out
The I²C engine releases both SDA and SCL if the I²C bus is held low for 2 seconds. If the fuel gauge is holding
the lines, releasing them frees them for the master to drive the lines.
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