T89C51RD2 ATMEL Corporation, T89C51RD2 Datasheet - Page 9

• Manufacturer Part Number: T89C51RD2
• Description: 0 to 40MHz Flash Programmable 8-bit Microcontroller
• Manufacturer: ATMEL Corporation

5.1. Pin Description for 64/68 pin Packages
Port 4 and Port 5 are 8-bit bidirectional I/O ports with internal pull-ups. Pins that have 1 written to them are pulled
high by the internal pull ups and can be used as inputs.
As inputs, pins that are externally pulled low will source current because of the internal pull-ups.
Refer to the previous pin description for other pins.
Rev. F - 15 February, 2001
VSS
VCC
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
RESET
ALE/PROG
PSEN
EA
XTAL1
XTAL2
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
P5.0
P5.1
P5.2
P5.3
P5.4
P5.5
P5.6
P5.7
PLCC68
51, 18
17
15
14
12
11
19
21
22
23
25
27
28
29
54
55
56
58
59
61
64
65
34
39
40
41
42
43
45
47
30
68
67
49
48
20
24
26
44
46
50
53
57
60
62
63
10
13
16
9
6
5
3
2
7
8
VQFP64 1.4
SQUARE
9/40
64
61
60
59
10
12
13
14
16
18
19
20
43
44
45
47
48
50
53
54
25
28
29
30
31
32
34
36
21
56
55
58
38
37
11
15
17
33
35
39
42
46
49
51
52
62
63
8
6
5
3
2
1
4
7
T89C51RD2
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