HD6412240 RENESAS [Renesas Technology Corp], HD6412240 Datasheet - Page 498

• Manufacturer Part Number: HD6412240
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2200 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 12 Serial Communication Interface (SCI)
Serial data transmission (clocked synchronous mode): Figure 12.16 shows a sample flowchart
for serial transmission.
The following procedure should be used for serial data transmission.
Rev.3.00 Mar. 26, 2007 Page 456 of 772
REJ09B0355-0300
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?
Start transmission
Initialization
TDRE = 1?
TEND = 1?
<End>
Figure 12.16 Sample Serial Transmission Flowchart
Yes
Yes
Yes
No
No
No
[3]
[2]
[1]
[1] SCI initialization:
[2] SCI status check and transmit data
[3] Serial transmission continuation
Note: * The case, in which the DTC
The TxD pin is automatically
designated as the transmit data output
pin.
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.
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.
Checking and clearing of the TDRE
flag is automatic when the DTC * is
activated by a transmit data empty
interrupt (TXI) request, and data is
written to TDR.
automatically clears the TDRE
flag, occurs only when DISEL in
DTC is 0 with the transfer
counter not being 0. Therefore,
the TDRE flag should be cleared
by CPU when DISEL is 1, or
when DISEL is 0 with the
transfer counter being 0.