14

AT89LS51

3053A–8051–05/02

Power-off sequence (if needed):

Set XTAL1 to “L” (if a crystal is not used).

Set RST to “L”.

Data Polling: The Data Polling feature is also available in the serial mode. In this mode, dur-

ing a write cycle an attempted read of the last byte written will result in the complement of the

MSB of the serial output byte on MISO.

Serial

Programming

Instruction Set

The Instruction Set for Serial Programming follows a 4-byte protocol and is shown in Table 8.

Programming

Interface –

Parallel Mode

Every code byte in the Flash array can be programmed by using the appropriate combination

of control signals. The write operation cycle is self-timed and once initiated, will automatically

time itself to completion.

Most major worldwide programming vendors offer support for the Atmel microcontroller series.

Please contact your local programming vendor for the appropriate software revision.

Notes:

1. Each PROG pulse is 200 ns - 500 ns for Chip Erase.

2. Each PROG pulse is 200 ns - 500 ns for Write Code Data.

3. Each PROG pulse is 200 ns - 500 ns for Write Lock Bits.

4. RDY/BSY signal is output on P3.0 during programming.

5. X = don’t care.

Table 7. Flash Programming Modes

Mode

RST

PSEN

ALE/

PROG

EA/

P2.6

P2.7

P3.3

P3.6

P3.7

P0.7-0

Data

P2.3-0

P1.7-0

Address

WriteCodeData

5V

H

L

(2)

12V

L

HHHH

A11-8

A7-0

Read Code Data

5V

H

L

H

H

L

L

L

H

H

A11-8

A7-0

Write Lock Bit 1

5V

H

L

(3)

12V

H

HHHH

X

X

X

Write Lock Bit 2

5V

H

L

(3)

12V

H

H

H

L

L

X

X

X

Write Lock Bit 3

5V

H

L

(3)

12V

H

L

H

H

L

X

X

X

Read Lock Bits

1, 2, 3

5V

H

L

H

H

H

H

L

H

L

P0.2,

P0.3,

P0.4

XX

Chip Erase

5V

H

L

(1)

12V

H

L

H

L

L

X

X

X

Read Atmel ID

5V

H

L

H

H

LLLLL

1EH

0000

00H

Read Device ID

5V

H

L

H

H

LLLLL

61H

0001

00H

Read Device ID

5V

H

L

H

H

LLLLL

06H

0010

00H