H8S2628_10 Datasheet, PDF (419/658 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2600 Series

Section 14 Serial Communication Interface (SCI)
14.9.5 SCI Operations during Mode Transitions
Transmission
Before making the transition to module stop, software standby, watch, sub-active, or sub-sleep
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 is cancelled and then the TE is set to 1 again. 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 14.33 shows a sample flowchart for mode transition during transmission. Figures 14.34 and
14.35 show the pin states during transmission.
Before making the transition from the transmission mode using DTC transfer to module stop,
software standby, watch, sub-active, or sub-sleep 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. 4.00 Mar. 16, 2010 Page 371 of 606
REJ09B0155-0400