SH7760 Datasheet, PDF (641/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

(4) Serial Data Transmission (Synchronous Mode)
Figure 17.17 shows a sample flowchart for serial transmission.
Use the following procedure for serial data transmission after enabling the SCIF for
transmission.
Initialization
[1]
Start of transmission
Read TDFE bit in SCFSR
[2]
No
TDFE = 1?
Yes
Write transmit data to SCFTDR
and clear TDFE bit and
TEND bit in SCFSR to 0
All data transmitted?
Yes
No
[3]
Read TEND flag in SCFSR
No
TEND = 1?
Yes
Clear TE bit in SCSCR to 0
[1] SCIF initialization:
See sample SCIF initialization
flowchart in figure 17.16.
[2] SCIF status check and transmit data
write:
Read SCFSR and check that the
TDFE flag is set to 1, then write
transmit data to SCFTDR, and clear
the TDFE flag to 0. The transition of
the TDFE flag from 0 to 1 can also be
identified by a TXI interrupt.
[3] Serial transmission continuation
procedeure:
To continue serial transmission, read
1 from the TDFE flag to confirm that
writing is possible, them write data to
SCFTDR, and then clear the TDFE
flag to 0.
End of transmission
Figure 17.17 Sample Serial Transmission Flowchart
In serial transmission, the SCIF operates as described below.
1. When data is written into SCFTDR, the SCIF transfers the data from SCFTDR to SCTSR and
starts transmitting. Confirm that the TDFE flag in SCFSR is set to 1 before writing transmit
data to SCFTDR. The number of data bytes that can be written is at least 128 (transmit trigger
setting).
2. When data is transferred from SCFTDR to SCTSR and transmission is started, consecutive
transmit operations are performed until there is no transmit data left in SCFTDR. When the
number of transmit data bytes in SCFTDR falls to or below the transmit trigger number set in
SCFCR, the TDFE flag is set. If the TIE bit in SCSCR is set to 1 at this time, a transmit-FIFO-
data-empty interrupt (TXI) request is generated.
Rev. 1.0, 02/03, page 591 of 1294