AT89S53

21

.

Notes:

1. “h” = weakly pulled “High” internally.

2. Chip Erase and Serial Programming Fuse require a 10 ms PROG pulse. Chip Erase needs to be performed first before

reprogramming any byte with a content other than FFH.

3. P3.4 is pulled Low during programming to indicate RDY/BSY.

4. “X” = don’t care

Flash Parallel Programming Modes

Mode

RST

PSEN

ALE/PROG

EA/V

PP

P2.6

P2.7

P3.6

P3.7

Data I/O

P0.7:0

Address

P2.5:0 P1.7:0

Serial Prog. Modes

H

h

(1)

h

(1)

x

Chip Erase

H

L

12V

H

L

L

L

X

X

Write (12K bytes) Memory

H

L

12V

L

H

H

H

DIN

ADDR

Read (12K bytes) Memory

H

L

H

12V

L

L

H

H

DOUT

ADDR

Write Lock Bits:

H

L

12V

H

L

H

L

DIN

X

Bit - 1

P0.7 = 0

X

Bit - 2

P0.6 = 0

X

Bit - 3

P0.5 = 0

X

Read Lock Bits:

H

L

H

12V

H

H

L

L

DOUT

X

Bit - 1

@P0.2

X

Bit - 2

@P0.1

X

Bit - 3

@P0.0

X

Read Atmel Code

H

L

H

12V

L

L

L

L

DOUT

30H

Read Device Code

H

L

H

12V

L

L

L

L

DOUT

31H

Serial Prog. Enable

H

L

12V

L

H

L

H

P0.0 = 0

X

Serial Prog. Disable

H

L

12V

L

H

L

H

P0.0 = 1

X

Read Serial Prog. Fuse

H

L

H

12V

H

H

L

H

@P0.0

X

(2)

(2)

(2)

Instruction Set

Notes:

1. DATA polling is used to indicate the end of a write cycle which typically takes less than 10 ms at 2.7V.

2. “x” = don’t care.

Instruction

Input Format

Operation

Byte 1

Byte 2

Byte 3

Programming Enable

1010 1100

0101 0011

xxxx xxxx

Enable serial programming interface after RST goes

high.

Chip Erase

1010 1100

xxxx x100

xxxx xxxx

Chip erase the 12K memory array.

Read Code Memory

low addr

xxxx xxxx

Read data from Code memory array at the selected

address. The 6 MSBs of the first byte are the high order

address bits. The low order address bits are in the

second byte. Data are available at pin MISO during the

third byte.

Write Code Memory

low addr

data in

Write data to Code memory location at selected

address. The address bits are the 6 MSBs of the first

byte together with the second byte.

Write Lock Bits

1010 1100

xxxx xxxx

Write lock bits.

Set LB1, LB2 or LB3 = “0” to program lock bits.

01

10

x x111