T89C51RD2-DDBI-L View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

T89C51RD2-DDBI-L

0 to 40 MHz Flash Programmable 8-bit Microcontroller

Atmel Corporation 

T89C51RD2

9.5.15. Clock Waveforms

Valid in normal clock mode. In X2 mode XTAL2 must be changed to XTAL2/2.

INTERNAL

CLOCK

XTAL2

STATE4

P1 P2

STATE5

P1 P2

STATE6

P1 P2

STATE1

P1 P2

STATE2

P1 P2

STATE3

P1 P2

STATE4

P1 P2

STATE5

P1 P2

ALE

EXTERNAL PROGRAM MEMORY FETCH

PSEN

THESE SIGNALS ARE NOT ACTIVATED DURING THE

EXECUTION OF A MOVX INSTRUCTION

P0

P2 (EXT)

DATA

SAMPLED

FLOAT

PCL OUT

DATA

SAMPLED

FLOAT

PCL OUT

INDICATES ADDRESS TRANSITIONS

DATA

SAMPLED

FLOAT

PCL OUT

READ CYCLE

RD

P0

P2

DPL OR Rt OUT

DATA

SAMPLED

FLOAT

INDICATES DPH OR P2 SFR TO PCH TRANSITION

PCL OUT (IF PROGRAM

MEMORY IS EXTERNAL)

WRITE CYCLE

WR

P0

P2

DPL OR Rt OUT

PCL OUT (EVEN IF PROGRAM

MEMORY IS INTERNAL)

DATA OUT

INDICATES DPH OR P2 SFR TO PCH TRANSITION

PCL OUT (IF PROGRAM

MEMORY IS EXTERNAL)

PORT OPERATION

MOV PORT SRC

OLD DATA NEW DATA

MOV DEST P0

P0 PINS SAMPLED

MOV DEST PORT (P1. P2. P3)

(INCLUDES INTO. INT1. TO T1)

P1, P2, P3 PINS SAMPLED

SERIAL PORT SHIFT CLOCK

TXD (MODE 0)

RXD SAMPLED

P0 PINS SAMPLED

P1, P2, P3 PINS SAMPLED

RXD SAMPLED

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 (TA=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.

85

Rev. F - 15 February, 2001

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