NEC PD78214 - Manual (Page 309)

280
µ
PD78214 Sub-Series
10.6.6 Busy Signal (BUSY) and Ready Signal (READY)
The busy signal informs the master device that the slave device is preparing for data transmission or reception.
The ready signal informs the master device that the slave device is ready for data transmission or reception.
Fig. 10-21 Busy Signal and Ready Signal
SCK
SB0
8 9
ACK BUSY READY
In SBI mode, the slave device drives the SB0 line low to inform the master device that the slave is busy.
The busy signal is output after the acknowledge signal is output by the master or slave device. The busy signal
is set or released in synchronization with the falling edge of SCK. When the busy signal is released, the master
device automatically terminates the output of the SCK serial clock.
The master device can start the next transfer when the busy signal is released and the ready signal is set.
10.6.7 Signals
Figs. 10-22 to 10-26 show the signals in SBI mode and the flag operations of the SBIC. Table 10-2 lists the SBI
signals.
Fig. 10-22 Operation of RELT, CMDT, RELD, and CMDD
SIO
SCK
SB0
RELT
CMDT
RELD
CMDD
Transfer start request