Datasheet

Section 12 Serial Communication Interface
Rev.7.00 Dec. 24, 2008 Page 423 of 698
REJ09B0074-0700
No
<End>
[1]
Yes
Initialization
Start transmission
Read TDRE flag in SSR [2]
Write transmit data to TDR and
clear TDRE flag in SSR to 0
No
Yes
No
Yes
Read TEND flag in SSR
[3]
Clear TE bit in SCR to 0
TDRE = 1
All data transmitted?
TEND = 1
[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.
Checking and clearing of the TDRE flag is
automatic when the DMAC is activated by a
transmit data empty interrupt (TXI) request
and data is written to TDR.
Figure 12.20 Sample Serial Data Transmission Flowchart