r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 902

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

Section 15 Serial Communication Interface (SCI, IrDA)
Rev. 1.00 Sep. 19, 2008 Page 872 of 1342
REJ09B0467-0100
Clear DR to 0 and set DDR to 1
Write transmit data to TDR and
Figure 15.11 Sample Multiprocessor Serial Transmission Flowchart
Read TDRE flag in SSR
Read TEND flag in SSR
Clear TE bit in SCR to 0
set MPBT bit in SSR
Clear TDRE flag to 0
Start of transmission
All data transmitted?
Break output?
Initialization
TDRE = 1?
TEND = 1?
<End>
Yes
Yes
Yes
Yes
No
No
No
No
[1]
[2]
[3]
[4]
[1]
[2]
[3]
[4]
SCI initialization:
The TxD pin is automatically
designated as the transmit data
output pin.
After the TE bit is set to 1,
a frame of 1s is output, and
transmission is enabled.
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. Set the
MPBT bit in SSR to 0 or 1.
Finally, 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. 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.
Break output at the end of serial
transmission:
To output a break in serial
transmission, set the port DDR to
1, clear DR to 0, then clear the
TE bit in SCR to 0.