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Initialize
Start transmitting
Read TDRE flag in SSR
TDRE = 1
Yes
Write transmit data in TDR
and set MPBT bit in SSR
Clear TDRE flag to 0
All data transmitted?
Yes
Read TEND flag in SSR
TEND = 1
Yes
Output break signal?
Yes
Clear DR bit to 0 and set DDR to 1
Clear TE bit to 0 in SCR
<End>
Figure 13.10 Sample Flowchart for Transmitting Multiprocessor Serial Data
(1)
SCI initialization:
(1)
the transmit data output function of the TxD pin
is selected automatically.
(2)
SCI status check and transmit data write:
read SSR, check that the TDRE flag is 1, then
write transmit data in TDR. Also set the MPBT
(2)
flag to 0 or 1 in SSR. Finally, clear the TDRE
flag to 0.
(3)
To continue transmitting serial data:
No
after checking that the TDRE flag is 1,
indicating that data can be written, write data
in TDR, then clear the TDRE flag to 0. When
the DMAC is activated by a transmit-data-
empty interrupt request (TXI) to write data in
TDR, the TDRE flag is checked and cleared
automatically.
(4)
To output a break signal at the end of serial
transmission:
set the DDR bit to 1 and clear the DR bit to 0
No
(DDR and DR are I/O port registers), then
(3)
clear the TE bit to 0 in SCR.
No
No
(4)
469
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