UPD78F1502AGK-GAK-AX Datasheet, PDF (625/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 15 SERIAL INTERFACE IICA
15.5.13 Wakeup function
The I²C bus slave function is a function that generates an interrupt request signal (INTIICA) when a local address and
extension code have been received.
This function makes processing more efficient by preventing unnecessary INTIICA 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.
However, when a stop condition is detected, bit 4 (SPIE) of IICA control register 0 (IICCTL0) is set regardless of the
wakeup function, and this determines whether interrupt requests are enabled or disabled.
To use the wakeup function in the STOP mode, set WUP to 1. Addresses can be received regardless of the operation
clock. An interrupt request signal (INTIICA) 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 WUP bit after this interrupt has
been generated.
Figure 15-22 shows the flow for setting WUP = 1 and Figure 15-23 shows the flow for setting WUP = 0 upon an
address match.
Figure 15-22. Flow When Setting WUP = 1
START
No
MSTS = STD = EXC = COI =0?
Yes
WUP = 1
Wait
Waits for 3 clocks.
STOP instruction execution
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Jun 20, 2011