Rainbow Electronics T89C51RD2 - Manual (Page 85)

85 Rev. F - 15 February, 2001
T89C51RD2
9.5.15. Clock Waveforms
Valid in normal clock mode. In X2 mode XTAL2 must be changed to XTAL2/2.
This diagram indicates when signals are clocked internally. The time it takes the signals to propagate to the pins,
however, ranges from 25 to 125 ns. This propagation delay is dependent on variables such as temperature and pin
loading. Propagation also varies from output to output and component. Typically though (T
A
=25
°
C fully loaded)
RD and WR propagation delays are approximately 50ns. The other signals are typically 85 ns. Propagation delays
are incorporated in the AC specifications.
DATA PCL OUT DATA PCL OUT DATA PCL OUT
SAMPLED SAMPLED SAMPLED
STATE4 STATE5 STATE6 STATE1 STATE2 STATE3 STATE4 STATE5
P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2
FLOAT FLOAT FLOAT
THESE SIGNALS ARE NOT ACTIVATED DURING THE
EXECUTION OF A MOVX INSTRUCTION
INDICATES ADDRESS TRANSITIONS
EXTERNAL PROGRAM MEMORY FETCH
FLOAT
DATA
SAMPLED
DPL OR Rt OUT
INDICATES DPH OR P2 SFR TO PCH TRANSITION
PCL OUT (IF PROGRAM
MEMORY IS EXTERNAL)
PCL OUT (EVEN IF PROGRAM
MEMORY IS INTERNAL)
PCL OUT (IF PROGRAM
MEMORY IS EXTERNAL)
OLD DATA NEW DATA
P0 PINS SAMPLED
P1, P2, P3 PINS SAMPLED P1, P2, P3 PINS SAMPLED
P0 PINS SAMPLED
RXD SAMPLED
INTERNAL
CLOCK
XTAL2
ALE
PSEN
P0
P2 (EXT)
READ CYCLE
WRITE CYCLE
RD
P0
P2
WR
PORT OPERATION
MOV PORT SRC
MOV DEST P0
MOV DEST PORT (P1. P2. P3)
(INCLUDES INTO. INT1. TO T1)
SERIAL PORT SHIFT CLOCK
TXD (MODE 0)
DATA OUT
DPL OR Rt OUT
INDICATES DPH OR P2 SFR TO PCH TRANSITION
P0
P2
RXD SAMPLED