Renesas H8S Series Hardware Manual page 535

• Serial data transmission (clocked synchronous mode)
Figure 14-16 shows a sample flowchart for serial transmission.
The following procedure should be used for serial data transmission.
Read TDRE flag in SSR
Write transmit data to TDR and
clear TDRE flag in SSR to 0
Read TEND flag in SSR
Clear TE bit in SCR to 0
Initialization
Start transmission
TDRE= 1
Yes
All data transmitted?
Yes
TEND= 1
Yes
<End>
Figure 14-16 Sample Serial Transmission Flowchart
[1] SCI initialization:
[1]
The TxD pin is automatically
designated as the transmit data output
pin.
[2] SCI status check and transmit data
[2]
write:
Read SSR and check that the TDRE
No
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
No
[3]
TDRE flag to 0.
Checking and clearing of the TDRE
flag is automatic when the DMAC or
DTC is activated by a transmit data
empty interrupt (TXI) request and data
is written to TDR.
No
Rev.6.00 Oct.28.2004 page 507 of 1016
REJ09B0138-0600H