Datasheet

Section 15 Serial Communication Interface (SCI, IrDA)
Page 944 of 1408 R01UH0309EJ0500 Rev. 5.00
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
15.10.7 Operation in Case of Mode Transition
(1) Transmission
Operation should be stopped (by clearing TE, TIE, and TEIE to 0) before setting the module stop
state or making a transition to software standby mode. TSR, TDR, and SSR are reset. The output
pin states in the module stop state or software standby mode depend on the port settings, and
become high-level output after the relevant mode is cleared. If a transition is made during
transmission, the data being transmitted will be undefined.
When transmitting without changing the transmit mode after the relevant mode is cleared,
transmission can be started by setting TE to 1 again, and performing the following sequence: SSR
read → TDR write → TDRE clearance. To transmit with a different transmit mode after clearing
the relevant mode, the procedure must be started again from initialization.
Figure 15.36 shows a sample flowchart for mode transition during transmission. Port pin states
during mode transition are shown in figures 15.37 and 15.38.
Operation should also be stopped (by clearing TE, TIE, and TEIE to 0) before making a transition
from transmission by DTC transfer to module stop state setting or software standby mode
transition. To perform transmission with the DTC after the relevant mode is cleared, setting TE
and TIE to 1 will set the TXI flag and start DTC transmission.
(2) Reception
Receive operation should be stopped (by clearing RE to 0) before setting the module stop state or
making a transition to software standby mode. RSR, RDR, and SSR are reset. If a transition is
made during reception, the data being received will be invalid.
To continue receiving without changing the reception mode after the relevant mode is cleared, set
RE to 1 before starting reception. To receive with a different receive mode, the procedure must be
started again from initialization.