SH7760 Datasheet, PDF (632/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

(4) Serial Data Transmission (Asynchronous Mode)
Figure 17.9 shows a sample flowchart for serial transmission.
Use the following procedure for serial data transmission after enabling the SCIF for
transmission.
Start of transmission
Read TDFE bit in SCFSR
No
TDFE = 1?
Yes
Write transmit data in SCFTDR,
[1]
and clear TDFE bit and
TEND bit in SCFSR to 0
All data transmitted?
Yes
No
[2]
Read TEND bit in SCFSR
TEND = 1?
Yes
Break output?
Yes
Clear SPB2DT to 0 and
set SPB2IO to 1
No
No
[3]
Clear TE bit in SCSCR to 0
[1] 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 and TEND flags to 0.
The number of transmit data bytes
that can be written is 128 - (transmit
trigger set number).
[2] Serial transmission continuation
procedure:
To continue serial transmission, read
1 from the TDFE flag to confirm that
writing is possible, then write data to
SCFTDR, and then clear the TDFE
flag to 0.
[3] Break output at the end of serial
transmission:
To output a break in serial
transmission, clear the SPB2DT bit to
0 and set the SPB2IO bit to 1 in
SCSPTR, then clear the TE bit in
SCSCR to 0.
In [1] and [2], it is possible to
ascertain the number of data bytes
that can be written from the number
of transmit data bytes in SCFTDR
indicated by SCTFDR.
End of transmission
Figure 17.9 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).
Rev. 1.0, 02/03, page 582 of 1294