H8S2339 Datasheet, PDF (678/1244 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series

Section 14 Serial Communication Interface (SCI)
Serial data transmission (synchronous mode): Figure 14.16 shows a sample flowchart for serial
transmission.
The following procedure should be used for serial data transmission.
Initialization
[1]
Start of transmission
Read TDRE flag in SSR
[2]
No
TDRE = 1?
Yes
Write transmit data to TDR and
clear TDRE flag in SSR to 0
All data transmitted?
Yes
Read TEND flag in SSR
TEND = 1?
Yes
No
[3]
No
[1] SCI initialization:
The TxD pin is automatically
designated as the transmit data output
pin.
[2] SCI status check and transmit data
write:
Read SSR and check that the TDRE
flag is set to 1, then write transmit data
to TDR and clear the TDRE flag to 0.
[3] Serial transmission continuation
procedure:
To continue serial transmission, be
sure to read 1 from the TDRE flag to
confirm that writing is possible, then
write data to TDR, and then clear the
TDRE flag to 0.
Checking and clearing of the TDRE
flag is automatic when the DMAC or
DTC is activated by a transmit-data-
empty interrupt (TXI) request and data
is written to TDR.
Clear TE bit in SCR to 0
<End>
Figure 14.16 Sample Serial Transmission Flowchart
Rev.4.00 Sep. 07, 2007 Page 648 of 1210
REJ09B0245-0400