ds2251t Maxim Integrated Products, Inc., ds2251t Datasheet - Page 4

• Manufacturer Part Number: ds2251t
• Description: Ds2251t 128k Soft Microcontroller Module
• Manufacturer: Maxim Integrated Products, Inc.

PIN ASSIGNMENT
PIN DESCRIPTION
PIN
10
11
12
13
14
15
16
17
18
39–32
21–28
1
2
3
4
5
6
7
8
9
PIN
1–8
10
11
12
13
14
P3.0/RXD
P3.1/TXD
P3.2/
P3.3/
P3.6/
P3.7/
P3.4/T0
P3.5/T1
XTAL1
NAME
RST
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P0.0–P0.7. General-purpose I/O Port 0. This port is open-drain and cannot 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.
P1.0–P1.7. General-purpose I/O Port 1.
P2.0–P2.7. General-purpose I/O Port 2. Also serves as the MSB of the Expanded Address
bus.
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.
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.
P3.2/
Interrupt 0.
P3.3/
Interrupt 1.
P3.4/T0. General-purpose I/O port pin 3.4. Also serves as the Timer 0 input.
INT0
INT1
WR
RD
INT0
INT1
. General-purpose I/O port pin 3.3. Also serves as the active low External
. General-purpose I/O port pin 3.2. Also serves as the active low External
PIN
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
XTAL2
NAME
PROG
GND
PSEN
ALE
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P0.7
P0.6
P0.5
P0.4
P0.3
4 of 22
DESCRIPTION
PIN
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
NAME
BA10
BA11
BA12
BA13
BA0
BA1
BA2
BA3
BA4
BA5
BA6
BA7
BA8
BA9
P0.2
P0.1
P0.0
V
CC
PIN
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
NAME
BA15
SQW
R/
VRST
INTA
INTB
BD0
BD1
BD2
BD3
BD4
BD5
BD6
BD7
INTP
PE3
PE4
PF
W