p2125vps20 Renesas Electronics Corporation., p2125vps20 Datasheet - Page 390

• Manufacturer Part Number: p2125vps20
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 15 Serial Communication Interface (SCI)
Rev. 1.00 Sep. 21, 2006 Page 352 of 658
REJ09B0310-0100
Write transmit data to TDR and
clear TDRE flag in SSR to 0
Read TDRE flag in SSR
Read TEND flag in SSR
Clear TE bit in SCR to 0
All data transmitted?
End of transmission
Start transmission
Initialization
TDRE = 1
TEND = 1
Figure 15.17 Sample Serial Transmission Flowchart
Yes
Yes
Yes
No
No
No
[1]
[2]
[3]
[4]
[1]
[2]
[3]
Note: The SMR, SCR, SCMR, and BRR
SCI initialization:
The TxD pin is automatically designated as
the transmit data output pin.
SCI status check and transmit data write:
Read SSR and check that the TDRE flag is
set to 1, then write transmit data to TDR
and clear the TDRE flag to 0.
Serial transmission continuation procedure:
To continue serial transmission, be sure to
read 1 from the TDRE flag to confirm that
writing is possible, then write data to TDR,
and then clear the TDRE flag to 0.
However, the TDRE flag is checked and
cleared automatically when the DTC is
initiated by a transmit data empty interrupt
(TXI) request and writes data to TDR.
registers should not be written to
during the period from the start to the
end of transmission. This does not
apply to the processing at step [4].