H8SX1544 Datasheet, PDF (541/974 Pages) Renesas Technology Corp – Renesas 32-Bit CISC Microcomputer H8SX Family/H8SX/1500 Series

Section 12 Serial Communication Interface (SCI)
12.9.8 SCI Operations during Mode Transitions
(1) Transmission
Before making the transition to module stop mode or software standby mode, stop the transmit
operations (TE = TIE = TEIE = 0). TSR, TDR, and SSR are reset. The states of the output pins
during module stop mode or software standby mode depend on the port settings, and the pins
output a high-level signal after mode cancellation. If the transition is made during data
transmission, the data being transmitted will be undefined.
To transmit data in the same transmission mode after mode cancellation, set the TE bit to 1, read
SSR, write to TDR, clear TDRE in this order, and then start transmission. To transmit data in a
different transmission mode, initialize the SCI first.
Figure 12.34 shows a sample flowchart for mode transition during transmission. Figures 12.35 and
12.36 show the port pin states during mode transition.
(2) Reception
Before making the transition to module stop mode or software standby mode, stop the receive
operations (RE = 0). RSR, RDR, and SSR are reset. If transition is made during data reception, the
data being received will be invalid.
To receive data in the same reception mode after mode cancellation, set the RE bit to 1, and then
start reception. To receive data in a different reception mode, initialize the SCI first.
Rev.2.00 Oct. 16, 2007 Page 487 of 916
REJ09B0381-0200