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Transmitting and Receiving Data
Transmitting Multiprocessor Serial Data: Figure 11-10 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
End
Figure 11-10 Sample Flowchart for Transmitting Multiprocessor Serial Data
No
Yes
No
Yes
No
Yes
No
Yes
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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.
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 (DDR and
DR are I/O port registers), then clear
the TE bit to 0 in SCR.
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4
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