Datasheet

Section 15 Serial Communication Interface (SCI and IrDA)
Rev. 3.00 Mar 21, 2006 page 389 of 788
REJ09B0300-0300
No
<End>
[1]
Yes
Initialization
Start 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
[1] 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.
[2] SCI status check and transmit
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.
[3] Serial transmission 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.
However, the TDRE flag is
checked and cleared
automatically when the DTC is
initiated by a transmit data empty
interrupt (TXI) request and writes
data to TDR.
[4] Break output at the end of serial
transmission:
To output a break in serial
transmission, set port DDR to 1,
clear DR to 0, and then clear the
TE bit in SCR to 0.
Figure 15.11 Sample Multiprocessor Serial Transmission Flowchart