Datasheet

DS89C430/DS89C450 Ultra-High-Speed Flash Microcontrollers
10 of 46
Figure 4. Serial Port Timing
t
XLXL
t
XHDV
t
XHDX
t
XHQX
t
QVXH
TRANSMIT
RECEIVE
ALE
WRITE TO SBUF
PSEN
RXD DATA OUT
TXD CLOCK
TXD CLOCK
R1
TI
WRITE TO SCON
TO CLEAR RI
RXD DATA IN
D0 DI D3 D4D2 D5 D6 D7
D7D6D5D4D3D2DID0
RXD DATA IN
TXD CLOCK
R
E
C
E
I
V
E
T
R
A
N
S
M
I
T
D0 DI D6 D7
WRITE TO SCON
TO CLEAR RI
R1
D0 DI D6 D7
1/(XTAL FREQ/12)
ALE
PSEN
WRITE TO SBUF
RXD DATA OUT
TXD CLOCK
TI
TXD CLOCK
SERIAL PORT (SYNCHRONOUS MODE)
SM2 = 0 TDX CLOCK = XTAL FREQ/12
SERIAL PORT (SYNCHRONOUS MODE)
SM2 = 1 TDX CLOCK = XTAL FREQ/4