BQ28550-R1 Datasheet, PDF (18/42 Pages) Texas Instruments – Single Cell Li-Ion Battery Gas Gauge

Not Recommended for New Designs
bq28550-R1
SLUSAS4A – OCTOBER 2012 – REVISED SEPTEMBER 2014
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Feature Description (continued)
Acknowledge Bits: An Acknowledge bit (A) is required after each data transfer byte to ensure correct
communications. This occurs when the receiving device pulls the SDA low before the rising edge of the
acknowledge-related clock pulse (ninth pulse), and keeps it low until the SCL returns low. There is also a No-
Acknowledge bit (N), which occurs when the receiver releases the SDA line (high) before the rising edge of
acknowledge-related clock pulse, and maintains the SDA line high until SCL returns low. The Acknowledge bit
indicates if a successful data transfer has occurred between the master and slave device. Monitoring this bit also
indicates an unsuccessful data transfer due to the receiving device being busy or as system fault occurrence.
Communication Format
A START command immediately followed by a STOP command is an illegal format.
MSB
S
Slave Address
R/W
A
Data
A
P
S = START Command
R/W = Read from slave device ("1") or Write to slave device ("0")
A = Acknowledge bit
P = STOP Command
Slave Address = 7-bit address field for register address
DATA = 8-bit data field
PEC = Packet Error Checking
Slave to Master
Master to Slave
Communication Format for Multi-Word with Packet Error Checking (PEC)
Table 2. Write Byte with PEC
1
7
1
1
8
1
8
1
8
1
1
S
Slave Address
W
A
Command
A
Data Byte
A
PEC
A
P
Code
Table 3. Write Word with PEC
1
7
1
1
8
1
8
1
8
1
8
1
1
S
Slave
W
A
Command
A
Data Byte
A
Data Byte
A
PEC
A
P
Address
Code
Low
High
Table 4. Read Byte with PEC
1
7
1
1
8
1
1
7
1
1
8
1
8
1
1
S
Slave
W
A
Command
A
S
Slave
R
A
Data Byte
A
PEC
A
P
Address
Code
Address
Table 5. Read Word with PEC
1
7
1
1
8
1
1
7
1
1
8
1
8
1
8
1
1
S
Slave Address W A Command A
S
Slave
R
A
Data
A
Data
A
PEC
A
P
Code
Address
Byte
Byte
Low
High
18
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