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RL78/G1A CHAPTER 13 SERIAL INTERFACE IICA
13.5.13 Wakeup function
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The I
2
C bus slave function is a function that generates an interrupt request signal (INTIICA0) when a local address and
extension code have been received.
This function makes processing more efficient by preventing unnecessary INTIICA0 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 WUP0 bit to 1. Addresses can be received regardless of the
operation clock. An interrupt request signal (INTIICA0) 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 WUP0 bit after this interrupt
has been generated.
Figure 13-22 shows the flow for setting WUP0 = 1 and Figure 13-23 shows the flow for setting WUP0 = 0 upon an
address match.
Figure 13-22. Flow When Setting WUP0 = 1
Waits for 3 clocks of f
MCK
.
Yes
No
START
WUP0 = 1
Wait
STOP instruction execution
MSTS0 = STD0 = EXC0 = COI0 =0?
R01UH0305EJ0200 Rev.2.00 601
Jul 04, 2013