HD643303x Hitachi, HD643303x Datasheet - Page 359

• Manufacturer Part Number: HD643303x
• Description: Hitachi Microcomputer
• Manufacturer: Hitachi

Transmitting Serial Data (Asynchronous Mode): Figure 11-5 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 11-5 Sample Flowchart for Transmitting Serial Data
Yes
Yes
Yes
Yes
No
No
No
No
1
2
3
4
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.
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.
344