HD6417705 Datasheet, PDF (463/739 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

When the clock source, etc., is changed, the TE and RE bits must be cleared to 0 before making
the change using the following procedure. When the TE bit is cleared to 0, the transmit shift
register (SCTSR) is initialized. Note that clearing the TE and RE bits to 0 does not change the
contents of SCSSR, SCFTDR, or SCFRDR. The TE bit should be cleared to 0 after all transmit
data has been sent and the TEND bit in SCSSR has been set to 1. The TE bit should not be cleared
to 0 during transmission; if attempted, the TxD pin will go to the high-impedance state. Before
setting TE to 1 again to start transmission, the TFRST bit in SCFCR should first be set to 1 to reset
SCFTDR.
Rev. 2.00, 09/03, page 417 of 690