HD6433044 Hitachi Semiconductor, HD6433044 Datasheet - Page 481

• Manufacturer Part Number: HD6433044
• Description: (HD64 Series) Hitachi Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

Transmitting Serial Data (Asynchronous Mode): Figure 13-5 shows a sample flowchart for
transmitting serial data and indicates the procedure to follow.
Read TDRE flag in SSR
Read TEND flag in SSR
Clear TE bit to 0 in SCR
in TDR and clear TDRE
Write transmit data
Clear DR bit to 0,
Start transmitting
set DDR bit to 1
flag to 0 in SSR
Output break
transmitted?
TDRE = 1?
TEND = 1?
Initialize
All data
signal?
End
Figure 13-5 Sample Flowchart for Transmitting Serial Data
Yes
Yes
Yes
Yes
No
No
No
No
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2
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1.
2.
3.
4.
SCI initialization: the transmit data output function
of the TxD pin is selected automatically.
SCI status check and transmit data write: read SSR,
check that the TDRE flag is 1, then write transmit data
in TDR and clear the TDRE flag to 0.
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.
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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