Rev. 1.0, 07/01, page 198 of 372
No
Yes
Start transmission
Read TDRE flag in SSR[1]
Write transmit data to TDR
Yes
No
No
Yes
Read TEND flag in SSR
[2]
No
Yes
[3]
Clear PDR to 0 and
set PCR to 1
Clear TE bit in SCR3 to 0
TDRE = 1
All data transmitted?
TEND = 1
Break output?
[1] 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. Checking and
clearing of the TDRE flag is
automatic.
[2] To continue serial transmission,
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.
[3] To output a break at the end of
serial transmission, after setting
PCR to 1 and clearing PDR to 0,
clear TxD in PMR1 to 0, then clear
the TE bit in VSCR3 to 0.
End
Figure 14-6 Sample Serial Transmission Data Flowchart (Asynchronous Mode)