Datasheet

Section 12 Serial Communication Interface (SCI)
Rev.7.00 Feb. 14, 2007 page 475 of 1108
REJ09B0089-0700
No
<End>
[1]
Yes
Initialization
Start of transmission
Read TDRE flag in SSR[2]
Write transmit data to TDR and
set MPBT bit in SSR
No
Yes
No
Yes
Read TEND flag in SSR
[3]
No
Yes
[4]
Clear DR to 0 and set DDR to 1
Clear TE bit in SCR to 0
TDRE = 1?
All data transmitted?
TEND = 1?
Break output?
Clear TDRE flag to 0
SCI initialization:
The TxD pin is automatically
designated as the transmit data
output pin.
After the TE bit is set to 1,
a frame of 1s is output, and
transmission is enabled.
SCI status check and transm
it
data write:
Read SSR and check that the
TDRE flag is set to 1, then write
transmit data to TDR. Set the
MPBT bit in SSR to 0 or 1.
Finally, clear the TDRE flag to 0.
Serial transm
ission 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 fla
g 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.
Break output at the end of serial
transmi
ssion:
To output a break in serial
transmission, set the port DDR to
1, clear DR to 0, then clear the
TE bit in SCR to 0.
[1]
[2]
[3]
[4]
Figure 12.10 Sample Multiprocessor Serial Transmission Flowchart