NCP6915
http://onsemi.com
14
I
2
C Compatible Interface
NCP6915 can support a subset of I
2
C protocol, below are
detailed introduction for I
2
C programming.
I
2
C Communication Description
ON Semiconductor communication protocol is a subset
of I
2
C protocol.
Figure 16. 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 NCP6915 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:
Figure 17. Read Out from Part
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.
