UPD78F1502AGK-GAK-AX Datasheet, PDF (633/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 15 SERIAL INTERFACE IICA
15.5.16 Communication operations
The following shows three operation procedures with the flowchart.
(1) Master operation in single master system
The flowchart when using the 78K0R/Lx3 microcontrollers 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 I²C bus multimaster system, whether the bus is released or used cannot be judged by the I²C 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/Lx3 microcontrollers take 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/Lx3 microcontrollers loose in arbitration and are 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/Lx3 microcontrollers are used as the I²C 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
INTIICA interrupt occurrence (communication waiting). When an INTIICA 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.
R01UH0004EJ0501 Rev.5.01
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Jun 20, 2011