CHAPTER 16 SERIAL INTERFACE IICA
User’s Manual U19780EJ2V0UD
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16.5.16 Communication operations
The following shows three operation procedures with the flowchart.
(1) Master operation in single master system
The flowchart when using the 78K0R/IE3 as the master in a single master system is shown below.
This flowchart is broadly divided into the initial settings and communication processing. Execute the initial
settings at startup. If communication with the slave is required, prepare the communication and then execute
communication processing.
(2) Master operation in multimaster system
In the I
2
C bus multimaster system, whether the bus is released or used cannot be judged by the I
2
C bus
specifications when the bus takes part in a communication. Here, when data and clock are at a high level for a
certain period (1 frame), the 78K0R/IE3 takes part in a communication with bus released state.
This flowchart is broadly divided into the initial settings, communication waiting, and communication processing.
The processing when the 78K0R/IE3 looses in arbitration and is specified as the slave is omitted here, and
only the processing as the master is shown. Execute the initial settings at startup to take part in a
communication. Then, wait for the communication request as the master or wait for the specification as the
slave. The actual communication is performed in the communication processing, and it supports the
transmission/reception with the slave and the arbitration with other masters.
(3) Slave operation
An example of when the 78K0R/IE3 is used as the I
2
C bus slave is shown below.
When used as the slave, operation is started by an interrupt. Execute the initial settings at startup, then wait
for the INTIICA0 interrupt occurrence (communication waiting). When an INTIICA0 interrupt occurs, the
communication status is judged and its result is passed as a flag over to the main processing.
By checking the flags, necessary communication processing is performed.