RL78/G13 CHAPTER 13 SERIAL INTERFACE IICA
R01UH0146EJ0100 Rev.1.00 728
Sep 22, 2011
13.5.7 Canceling wait
The I
2
C usually cancels a wait state by the following processing.
• Writing data to the IICA shift register 0 (IICA0)
• Setting bit 5 (WREL0) of IICA control register 00 (IICCTL00) (canceling wait)
• Setting bit 1 (STT0) of the IICCTL00 register (generating start condition)
Note
• Setting bit 0 (SPT0) of the IICCTL00 register (generating stop condition)
Note
Note Master only
When the above wait canceling processing is executed, the I
2
C cancels the wait state and communication is resumed.
To cancel a wait state and transmit data (including addresses), write the data to the IICA0 register.
To receive data after canceling a wait state, or to complete data transmission, set bit 5 (WREL0) of the IICCTL00
register to 1.
To generate a restart condition after canceling a wait state, set bit 1 (STT0) of the IICCTL00 register to 1.
To generate a stop condition after canceling a wait state, set bit 0 (SPT0) of the IICCTL00 register to 1.
Execute the canceling processing only once for one wait state.
If, for example, data is written to the IICA0 register after canceling a wait state by setting the WREL0 bit to 1, an
incorrect value may be output to SDAA0 line because the timing for changing the SDAA0 line conflicts with the timing for
writing the IICA0 register.
In addition to the above, communication is stopped if the IICE0 bit is cleared to 0 when communication has been
aborted, so that the wait state can be canceled.
If the I
2
C bus has deadlocked due to noise, processing is saved from communication by setting bit 6 (LREL0) of the
IICCTL00 register, so that the wait state can be canceled.
Caution If a processing to cancel a wait state is executed when WUP0 = 1, the wait state will not be canceled.
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