Renesas Hitachi H8S/2191, Hardware Manual

Page: 515 / 1065

Rev. 2.0, 11/00, page 488 of 1037
(b) Serial Data Transmission (Clock Synchronous Mode)
Figure 23.16 shows a sample flowchart for serial transmission.
The following procedure should be used for serial data transmission.
No
< End >
[1]
Yes
Initialization
Start transmission
Read TDRE flag in SSR1 [2]
Write transmit data to TDR1 and
clear TDRE flag in SSR1 to 0
No
Yes
No
Yes
Read TEND flag in SSR1
[3]
Clear TE bit in
SCR1 to 0
TDRE=1
All data transmitted?
TEND=1
SCI1 initialization:
The SO1 pin is automatically designated as
the transmit data output pin.
SCI1 status check and transmit data write:
Read SSR1 and check that the TDRE flag
is set to 1, then write transmit data to TDR1
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 TDR1,
and then clear the TDRE flag to 0.
[1]
[2]
[3]
Figure 23.16 Sample Serial Transmission Flowchart