Datasheet

Section 15 Serial Communication Interface (SCI, IrDA)
Rev.7.00 Mar. 18, 2009 page 736 of 1136
REJ09B0109-0700
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 transmi
t
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 transmiss
ion 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
DMAC or DTC is activated by a
transmit-data-empty interrupt
(TXI) request, and data is written
to TDR.
Break output at the end of seria
l
transmission:
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 15.11 Sample Multiprocessor Serial Transmission Flowchart