NCP1850 Datasheet, PDF (20/30 Pages) ON Semiconductor – Fully Integrated Li-Ion Switching Battery Charger

NCP1850
I²C description
NCP1850 can support a subset of I²C protocol, below are detailed introduction for I²C programming.
FROM MCU to NCPxxxx
FROM NCPxxxx to MCU
START
IC ADRESS
1 ACK
DATA 1
ACK
DATA n
/ACK STOP ^{READ OUT FROM PART}
START
1 à READ
IC ADRESS
0 ACK
0 à WRITE
DATA 1
ACK
DATA n
/ACK
ACK
STOP
WRITE INSIDE PART
If PART down not Acknowledge, the /NACK will be followed b a STOP or Sr
If PART Acknowledges, the ACK can be followed by another data or Stop or Sr
Figure 11. General Protocol Description
The first byte transmitted is the Chip address (with LSB bit sets to 1 for a read operation, or sets to 0 for a Write operation).
Then the following data will be:
− In case of a Write operation, the register address (@REG) we want to write in followed by the data we will write in the
chip. The writing process is incremental. So the first data will be written in @REG, the second one in @REG + 1 .
The data are optional.
− In case of read operation, the NCP1850 will output the data out from the last register that has been accessed by the last
write operation. Like writing process, reading process is an incremental process.
Read Out from Part
The Master will first make a “Pseudo Write” transaction with no data to set the internal address register. Then, a stop then start
or a Repeated Start will initiate the read transaction from the register address the initial write transaction has set:
FROM MCU to NCPxxxx
FROM NCPxxxx to MCU
START
IC ADRESS
0 ACK
STETS INTERNAL
REGISTER POINTER
REGISTER ADRESS
ACK STOP
0 à WRITE
START
IC ADRESS
1 à READ
1 ACK
DATA 1
REGISTER ADRESS
VALUE
ACK
n REGISTERS READ
Figure 12. Read Out from Part
DATA n
REGISTER ADRESS + (n − 1)
VALUE
/ACK
STOP
The first WRITE sequence will set the internal pointer on the register we want access to. Then the read transaction will start
at the address the write transaction has initiated.
Write in Part:
Write operation will be achieved by only one transaction. After chip address, the MCU first data will be the internal register
we want access to, then following data will be the data we want to write in Reg, Reg + 1, Reg + 2, ., Reg +n.
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