t89c51rd2-slscl ATMEL Corporation, t89c51rd2-slscl Datasheet - Page 94

• Manufacturer Part Number: t89c51rd2-slscl
• Description: 0 To 40 Mhz Flash Programmable 8-bit Microcontroller
• Manufacturer: ATMEL Corporation

Clock Waveforms
94
EXTERNAL PROGRAM MEMORY FETCH
READ CYCLE
WRITE CYCLE
PORT OPERATION
SERIAL PORT SHIFT CLOCK
MOV PORT SRC
INTERNAL
T89C51RD2
MOV DEST PORT (P1. P2. P3)
(INCLUDES INTO. INT1. TO T1)
MOV DEST P0
P2 (EXT)
TXD (MODE 0)
CLOCK
XTAL2
PSEN
ALE
WR
RD
P0
P0
P2
P0
P2
SAMPLED
DATA
STATE4
P1
FLOAT
P2
STATE5
P1
PCL OUT
INDICATES ADDRESS TRANSITIONS
DPL OR Rt OUT
DPL OR Rt OUT
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
WR propagation delays are approximately 50ns. The other signals are typically 85 ns.
Propagation delays are incorporated in the AC specifications.
P0 PINS SAMPLED
P2
P1, P2, P3 PINS SAMPLED
RXD SAMPLED
INDICATES DPH OR P2 SFR TO PCH TRANSITION
INDICATES DPH OR P2 SFR TO PCH TRANSITION
STATE6
P1
OLD DATA NEW DATA
P2
FLOAT
SAMPLED
DATA
STATE1
P1
P2
STATE2
P1
PCL OUT
THESE SIGNALS ARE NOT ACTIVATED DURING THE
EXECUTION OF A MOVX INSTRUCTION
DATA OUT
FLOAT
P2
SAMPLED
DATA
STATE3
P1
P2
FLOAT
P1, P2, P3 PINS SAMPLED
P0 PINS SAMPLED
SAMPLED
DATA
STATE4
P1
PCL OUT (EVEN IF PROGRAM
MEMORY IS INTERNAL)
P2
MEMORY IS EXTERNAL)
RXD SAMPLED
PCL OUT (IF PROGRAM
PCL OUT (IF PROGRAM
MEMORY IS EXTERNAL)
A
STATE5
P1
PCL OUT
=25°C fully loaded) RD and
P2
4243G–8051–05/03