Sci Operations During Mode Transitions - Renesas H8S Family Hardware Manual

Section 13 Serial Communication Interface (SCI)

SCI Operations during Mode Transitions

Transmission: Before making the transition to module stop or software standby mode, stop all

transmit operations (TE = TIE = TEIE = 0). TSR, TDR, and SSR are reset. The states of the output

pins during each 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 TE 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 13.34 shows a sample flowchart for mode transition during transmission. Figures 13.35 and

13.36 show the pin states during transmission.

Before making the transition from the transmission mode using DTC transfer to module stop or

software standby mode, stop all transmit operations (TE = TIE = TEIE = 0). Setting TE and TIE to

1 after mode cancellation generates a TXI interrupt request to start transmission using the DTC.

Rev. 1.00 Mar. 12, 2008 Page 491 of 1178

REJ09B0403-0100