Renesas SH7781 - Manual (Page 1108)

21. Serial Communication Interface with FIFO (SCIF)
Rev.1.00 Jan. 10, 2008 Page 1078 of 1658
REJ09B0261-0100
(4) Serial Data Transmission (Asynchronous Mode)
Figure 21.9 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 flag in SCFSR
TDFE = 1?
Write transmit data in SCFTDR,
and clear TDFE and TEND bits
in SCFSR to 0
All data transmitted?
Read TEND bit in SCFSR
TEND = 1?
Break output?
Clear SPB2DT to 0 and
set SPB2IO to 1
Clear TE bit in SCSCR to 0
End of transmission
No
Yes
No
Yes
No
Yes
No
Yes
[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 64 - (transmit
trigger setting count).
[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.
[1]
[2]
[3]
Figure 21.9 Sample Serial Transmission Flowchart