Figure 16.20 Sample Serial Transmission Flowchart - Renesas H8S/2158 User Manual

Section 16 Serial Communication Interface (SCI, IrDA, and CRC)
Initialization
Start transmission
Read TDRE flag in SSR
TDRE = 1
Write transmit data to TDR and
clear TDRE flag in SSR to 0
All data transmitted?
Read TEND flag in SSR
TEND = 1
Clear TE bit in SCR to 0
<End>

Figure 16.20 Sample Serial Transmission Flowchart

Rev. 3.00 Jan 25, 2006 page 440 of 872
REJ09B0286-0300
[1]
[2]
No
Yes
No
[3]
Yes
No
Yes
[1] SCI initialization:
The TxD pin is automatically
designated as the transmit data output
pin.
[2] 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.
[3] 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.