HD6432633 Datasheet, PDF (784/1453 Pages) Renesas Technology Corp – Series of Microcomputers (MCUs: microcomputer units)

• Serial data transmission (asynchronous mode)
Figure 16-5 shows a sample flowchart for serial transmission.
The following procedure should be used for serial data transmission.
Initialization
Start transmission
Read TDRE flag in SSR
TDRE=1
Yes
Write transmit data to TDR
and clear TDRE flag in SSR to 0
All data transmitted?
Yes
Read TEND flag in SSR
TEND= 1
Yes
Break output?
Yes
Clear DR to 0 and
set DDR to 1
Clear TE bit in SCR to 0
[1] ^{[1] SCI initialization:}
The TxD pin is automatically
designated as the transmit data
output pin.
After the TE bit is set to 1, a frame
[2]
of 1s is output, and transmission is
enabled.
No
[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:
No
To continue serial transmission,
read 1 from the TDRE flag to
confirm that writing is possible,
then write data to TDR, and then
[3]
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
No
data empty interrupt (TXI) request,
and date is written to TDR.
[4] Break output at the end of serial
transmission:
No
[4]
To output a break in serial
transmission, set DDR for the port
corresponding to the TxD pin to 1,
clear DR to 0, then clear the TE bit
in SCR to 0.
Note: * DMAC and DTC functions are
not available in the H8S/2695.
<End>
Figure 16-5 Sample Serial Transmission Flowchart
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