D12320VF25V Datasheet, PDF (518/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 12 Serial Communication Interface (SCI)
Serial data transmission (synchronous mode): Figure 12.16 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 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 12.16 Sample Serial Transmission Flowchart
Rev.7.00 Feb. 14, 2007 page 484 of 1108
REJ09B0089-0700