RL78/G15 CHAPTER 13 SERIAL INTERFACE IICA
R01UH0959EJ0110 Rev.1.10 Page 554 of 765
Mar 7, 2023
13.5.16 Communication operations
The following describes three operation procedures as flows.
1) Master operation in single master system
The flow when the device is used as a master in the single master system is described.
This flow is broadly divided into the initial settings and communication processing. Execute the initial settings at startup. If
communication with the slave is required, make necessary preparation for communication and then execute
communication processing.
2) Master operation in multi-master system
In the I
2
C bus multi-master system, whether the bus is released or used cannot be judged only by the I
2
C bus
specifications at the stage when a device participates in communications. Here, when the data and clock are at the high
level for a certain period (1 frame), the device participates in communications in the bus released state.
This flow is broadly divided into the initial settings, communication waiting, and communication processing. The
processing when the device loses in arbitration and is specified as a slave is omitted here, and only the processing as a
master is shown. Execute the initial settings at startup to participate in communications. Then, wait for a communication
request as a master or wait for specification as a slave. The actual communication is performed in the communication
processing, and it supports transmission/reception with the slave and the arbitration with other masters.
3) Slave operation
An example when the device is used as a slave of the I
2
C bus is explained below.
When used as a 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 state is
judged and the result is passed to the main processing as a flag.
By checking each flag, the required communication processing is performed.
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