DS2252T

4 of 15

PIN ASSIGNMENT

1

P1.0

11

P1.5

21

P3.1 TXD

31

12

P0.4

22

ALE

32

P2.4

3

P1.1

13

P1.6

23

33

4

P0.0

14

P0.5

24

PROG

34

P2.3

5

P1.2

15

P1.7

25

35

XTAL2

6

P0.1

16

P0.6

26

P2.7

36

P2.2

7

P1.3

17

RST

27

P3.4 T0

37

XTAL1

8

P0.2

18

P0.7

28

P2.6

38

P2.1

9

P1.4

19

P3.0 RXD

29

P3.5 T1

39

GND

10

P0.3

20

SDI

30

P2.5

40

P2.0

PIN DESCRIPTION

PIN

DESCRIPTION

4, 6, 8, 10,

12, 14, 16,

18

P0.0 - P0.7. General purpose I/O Port 0. This port is open-drain and can not drive a logic

1. It requires external pullups. Port 0 is also the multiplexed Expanded Address/Data bus.

When used in this mode, it does not require pullups.

1, 3, 5, 7,

9, 11, 13,

15

P1.0 - P1.7. General purpose I/O Port 1.

40, 38, 36,

34, 32, 30,

28, 26

P2.0 - P2.7. General purpose I/O Port 2. Also serves as the MSB of the Expanded

Address bus.

19

P3.0 RXD. General purpose I/O port pin 3.0. Also serves as the receive signal for the on

board UART. This pin should NOT be connected directly to a PC COM port.

21

P3.1 TXD. General purpose I/O port pin 3.1. Also serves as the transmit signal for the on

board UART. This pin should NOT be connected directly to a PC COM port.

23

Clock.

25

Interrupt 1.

27

P3.4 T0. General purpose I/O port pin 3.4. Also serves as the Timer 0 input.

29

P3.5 T1. General purpose I/O port pin 3.5. Also serves as the Timer 1 input.

31

operation.

33

operation.

17

RST - Active high reset input. A logic 1 applied to this pin will activate a reset state. This

pin is pulled down internally, can be left unconnected if not used. An RC power-on reset

circuit is not needed and is NOT recommended.