H8S68 Datasheet, PDF (684/1044 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip MicrocomputerH8S Family/H8S/2300 Series

Section 14 Serial Communication Interface (SCI, IrDA)
14.10.7 Operation in Case of Mode Transition
• Transmission
Operation should be stopped (by clearing TE, TIE, and TEIE to 0) before making a module
stop mode or software standby mode transition. TSR, TDR, and SSR are reset. The output pin
states in module stop mode 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 14.36 shows a sample flowchart for mode transition during transmission. Port pin states
during mode transition are shown in figures 14.37 and 14.38.
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 mode 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.
• Reception
Receive operation should be stopped (by clearing RE to 0) before making a module stop mode
or software standby mode transition. 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.
Rev.6.00 Mar. 18, 2009 Page 624 of 980
REJ09B0050-0600