bq2011K
logic-low state for a period, tSTRH,B. The next section is the
actual data transmission, where the data should be valid by
a period, tDSU, after the negative edge used to start commu-
nication. The data should be held for a period, tDV, to allow
the host or bq2011K to sample the data bit.
The W/R bit of the command register is used to select
whether the received command is for a read or a write
function.
The W/R values are:
CMDR Bits
The final section is used to stop the transmission by return-
ing the DQ pin to a logic-high state by at least a period,
7
6
-
5
4
3
2
1
0
t
SSU, after the negative edge used to start communication.
The final logic-high state should be held until a period, tSV
W/R
-
-
-
-
-
-
,
to allow time to ensure that the bit transmission was
stopped properly. The timings for data and break communi-
cation are given in the serial communication timing specifi-
cation and illustration sections.
Where W/R is:
0
The bq2011K outputs the requested regis-
ter contents specified by the address por-
tion of CMDR.
Communication with the bq2011K is always performed
with the least-significant bit being transmitted first.
Figure 3 shows an example of a communication se-
quence to read the bq2011K NAC register.
1
The following eight bits should be written
to the register specified by the address por-
tion of CMDR.
bq2011K Registers
The bq2011K command and status registers are listed in
Table 5 and described below.
The lower seven-bit field of CMDR contains the address
portion of the register to be accessed. Attempts to write
to invalid addresses are ignored.
Command Register (CMDR)
CMDR Bits
The write-only CMDR register is accessed when eight
valid command bits have been received by the bq2011K.
The CMDR register contains two fields:
7
6
5
4
3
2
1
0
AD0
(LSB)
-
AD6 AD5 AD4 AD3 AD2 AD1
ꢀ
W/R bit
Primary Status Flags Register (FLGS1)
ꢀ
Command address
The read-only FLGS1 register (address=01h) contains
the primary bq2011K flags.
Written by Host to bq2011K Received by Host to bq2011K
CMDR = 03h
NAC = 65h
LSB
MSB LSB
0 0
MSB
Break 1 1 0
0
0
0
1 0 1 0 0 1 1 0
DQ
TD201103.eps
Figure 3. Typical Communication With the bq2011K
9
TI [ TEXAS INSTRUMENTS ]
