Hitachi H8S/2378, H8S/2378R Series Hardware Manual page 747

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. 1.0, 09/01, page 703 of 904