RL78/G1H CHAPTER 15 SERIAL INTERFACE IICA
R01UH0575EJ0120 Rev. 1.20 Page 462 of 920
Dec 22, 2016
15.5.13 Wakeup function
The I
2
C bus slave function is a function that generates an interrupt request signal (INTIICAn) when a local
address and extension code have been received.
This function makes processing more efficient by preventing unnecessary INTIICAn signal from occurring when
addresses do not match.
When a start condition is detected, wakeup standby mode is set. This wakeup standby mode is in effect while
addresses are transmitted due to the possibility that an arbitration loss may change the master device (which has
generated a start condition) to a slave device.
To use the wakeup function in the STOP mode, set the WUPn bit to 1. Addresses can be received regardless of
the operation clock. An interrupt request signal (INTIICAn) is also generated when a local address and extension
code have been received. Operation returns to normal operation by using an instruction to clear (0) the WUPn bit
after this interrupt has been generated.
Figure 15 - 28 shows the flow for setting WUPn = 1 and Figure 15 - 29 shows the flow for setting WUPn = 0 upon
an address match.
Figure 15 - 28 Flow When Setting WUPn = 1
Remark n = 0, 1
WUPn = 1
MSTSn = STDn = EXCn = COIn = 0?
No
Yes
Wait
STOP instruction execution
Wait for 3 fMCK clocks.
START
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