Pin Configurations
TQFP
PDIP
(T2) P1.0
(T2 EX) P1.1
P1.2
1
2
3
4
5
6
7
8
9
40 VCC
39 P0.0 (AD0)
38 P0.1 (AD1)
37 P0.2 (AD2)
36 P0.3 (AD3)
35 P0.4 (AD4)
34 P0.5 (AD5)
33 P0.6 (AD6)
32 P0.7 (AD7)
31 EA/VPP
P1.3
(SS) P1.4
(MOSI) P1.5
(MISO) P1.6
(SCK) P1.7
RST
(MOSI) P1.5
(MISO) P1.6
(SCK) P1.7
RST
1
2
3
4
5
6
7
8
9
33 P0.4 (AD4)
32 P0.5 (AD5)
31 P0.6 (AD6)
30 P0.7 (AD7)
29 EA/VPP
(RXD) P3.0 10
(TXD) P3.1 11
(INT0) P3.2 12
(INT1) P3.3 13
(T0) P3.4 14
(T1) P3.5 15
(WR) P3.6 16
(RD) P3.7 17
XTAL2 18
(RXD) P3.0
NC
30 ALE/PROG
29 PSEN
28 NC
(TXD) P3.1
(INT0) P3.2
(INT1) P3.3
27 ALE/PROG
26 PSEN
28 P2.7 (A15)
27 P2.6 (A14)
26 P2.5 (A13)
25 P2.4 (A12)
24 P2.3 (A11)
23 P2.2 (A10)
22 P2.1 (A9)
21 P2.0 (A8)
25 P2.7 (A15)
24 P2.6 (A14)
23 P2.5 (A13)
(T0) P3.4 10
(T1) P3.5 11
XTAL1 19
GND 20
PLCC
(MOSI) P1.5
(MISO) P1.6
(SCK) P1.7
7
8
9
39 P0.4 (AD4)
38 P0.5 (AD5)
37 P0.6 (AD6)
36 P0.7 (AD7)
35 EA/VPP
34 NC
RST 10
(RXD) P3.0 11
NC 12
(TXD) P3.1 13
(INT0) P3.2 14
(INT1) P3.3 15
(T0) P3.4 16
(T1) P3.5 17
33 ALE/PROG
32 PSEN
31 P2.7 (A15)
30 P2.6 (A14)
29 P2.5 (A13)
Pin Description
VCC
Supply voltage.
Ground.
GND
Port 0
Port 0 is an 8-bit open drain bi-didirectional I/O port. As an output port, each pin can
sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-
impedance inputs.
Port 0 can also be configured to be the multiplexed low-order address/data bus during
accesses to external program and data memory. In this mode, P0 has internal pull-ups.
Port 0 also receives the code bytes during Flash programming and outputs the code
bytes during program verification. External pull-ups are required during program
verification.
Port 1
Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output buffers
can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high
by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are exter-
nally being pulled low will source current (IIL) because of the internal pull-ups.
2
AT89S8252
0401G–MICRO–3/06
ATMEL [ ATMEL ]
