
450
(1) STS Instruction Wait State: The serial interface enters the STS instruction wait state on a
system reset (items 00 and 10 in figure 20-4).
The STS instruction wait state is the state in which the serial interface internal state is initialized.
In this state, the serial interface will not operate even if a transfer clock is applied. When an STS
instruction is executed ( 01 or 11 ) the serial interface switches to the transfer clock wait state.
(2) Transfer Clock Wait State: The transfer clock wait state is the period between the execution
of an STS instruction and the first transfer clock falling edge.
When the transfer clock is applied ( 02 or 12 ) with the serial interface in the transfer clock wait
state, the OC counter is incremented, the SRL/U pair shift operation starts, and the serial interface
switches to the transfer state. However, when transfer clock continuous output mode is selected in
internal clock mode, the serial interface does not switch to the transfer state, but rather it switches
to the transfer clock continuous output state ( 17 ).
If SMR is written when the serial interface is in the transfer clock wait state, the serial interface
switches to the STS instruction wait state ( 04 or 14 ).
(3) Transfer State: Transfer state is the period between the first transfer clock falling edge and
the eighth transfer clock rising edge.
If either an STS instruction is executed or eight transfer clock cycles are applied, OC is cleared to
000 and the serial interface state switches. If an STS instruction was executed ( 05 or 15 ), the
serial interface switches to the transfer clock wait state. If eight transfer clock cycles were applied,
the serial interface transfers to either the transfer clock wait state ( 03 ) if it was in external clock
mode, or the STS instruction wait state ( 13 ) if it was in internal clock mode.
In internal clock mode, the transfer clock stops after eight clock cycles.
If SMR is written in the transfer state ( 06 or 16 ), the serial interface is initialized and it switches
to the STS instruction wait state.
When a transition from transfer state to any other state occurs, OC is cleared to 000 and IFS is set
to 1.
(4) Transfer Clock Continuous Output State (Internal Clock Mode Only): Transfer clock
continuous output state is a state in which no data transfer is performed but the transfer clock is
output continuously from the
SCK pin. When the PMRA PMRA1 and PMRA0 bits are set to 00
and the serial interface is in the transfer clock wait state, if the transfer clock is applied ( 17 ), the
serial interface switches to the transfer clock continuous output state. If SMR is written in the
transfer clock continuous output state ( 18 ), the serial interface is initialized and it switches to the
STS instruction wait state.