CMS32L051 User Manual |Chapter 14 Serial interface IICA
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14.5.14 Communicate with reservation
(1) Cases where the communication reservation function is allowed (bit0(IICRSVn) = 0 for IICA flag
register n (IICFn))
To perform the next master communication without joining the bus, you can send a start condition when
the bus is released by making a communication appointment. At this time, do not join the bus includes the
following two states:
When the arbitration result is neither a master nor a slave
(LRELn) of the IICA control register n0 (IICCTLn0). 1, the bus is released after exiting communication).
If bit1 (STTn) of the IICCTLn0 register is set to 1 without joining the bus, a start condition is
automatically generated after the bus is released (stop condition detected) and enters a waiting state.
Put bit4 (SPIEn) of the IICCTLn0 register to 1 after the release of the bus (stop condition detected) is
detected by the resulting interrupt request signal (INTIICAn), if given The IICA shift register n (IICAn) writes
the address and automatically begins communication as the master device. The data written to the IICAn
register is invalid until a stop condition is detected.
When stTn is set to "1", it is decided whether to run as a start condition or as a communication
appointment depending on the bus state.
Generate start conditions
bus is not in the released state (standby)... Communicate with an appointment
After setting the STTn bit to "1" and the wait time has elapsed, the MSTSn bit (bit 7 of the IICA status
register n (IICSn)) is used to confirm whether or not to operate as a communication reservation.
The wait time calculated by the following calculation must be ensured by software:
Note 1. IICWLn: IICA low width setting register n
IICWHn : IICA high level width setting register n
t
F
: Falling time for SDAAn signal and SCLAn signal
f
MCK
: IICA operates at the clock frequency
2. n=0
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