HD64F2168 Datasheet, PDF (442/874 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer

Initialization
[1]
Start 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
No
[3]
[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.
However, the TDRE flag is checked
and cleared automatically when the
DTC is initiated by a transmit data
empty interrupt (TXI) request and
writes data to TDR.
No
TEND = 1
Yes
Clear TE bit in SCR to 0
<End>
Figure 14.20 Sample Serial Transmission Flowchart
Rev. 3.00, 03/04, page 402 of 830