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Transmitting and Receiving Data
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Transmitting Multiprocessor Serial Data: Figure 13-10 shows a sample flowchart for
transmitting multiprocessor serial data and indicates the procedure to follow.
Initialize
Start transmitting
Read TDRE flag in SSR
TDRE = 1?
Write transmit data in
TDR and set MPBT bit in SSR
Clear TDRE flag to 0
All data transmitted?
Read TEND flag in SSR
TEND = 1?
Output break signal?
Clear DR bit to 0, set DDR bit to 1
Clear TE bit to 0 in SCR
Figure 13-10 Sample Flowchart for Transmitting Multiprocessor Serial Data
No
Yes
No
Yes
No
Yes
No
Yes
End
1
1.
SCI initialization: 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
2
data in TDR. Also set the MPBT flag to
0 or 1 in SSR. Finally, clear the TDRE
flag to 0.
3.
To continue transmitting serial data:
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
3
1 and clear the DR bit to 0 (DDR and
DR are I/O port registers), then clear
the TE bit to 0 in SCR.
4
477
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