6
4431E–8051–04/06
AT/TS8xC54/8X2
Table 5-1.
Pin Description for 40/44 pin packages
MNEMONIC
PIN NUMBER
TYPE
Name And Function
DIL
LCC
VQFP 1.4
VSS
20
22
16
I
Ground: 0V reference
Vss1
1
39
I
Optional Ground: Contact the Sales Office for ground connection.
VCC
40
44
38
I
Power Supply: This is the power supply voltage for normal, idle and power-down
operation
P0.0-P0.7
39-32
43-36
37-30
I/O
Port 0: Port 0 is an open-drain, bidirectional I/O port. Port 0 pins that have 1s written to
them float and can be used as high impedance inputs. Port 0 pins must be polarized to
Vcc or Vss in order to prevent any parasitic current consumption. Port 0 is also the
multiplexed low-order address and data bus during access to external program and
data memory. In this application, it uses strong internal pull-up when emitting 1s. Port 0
also inputs the code bytes during EPROM programming. External pull-ups are required
during program verification during which P0 outputs the code bytes.
P1.0-P1.7
1-8
2-9
40-44
1-3
I/O
Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. Port 1 pins that
have 1s written to them are pulled high by the internal pull-ups and can be used as
inputs. As inputs, Port 1 pins that are externally pulled low will source current because
of the internal pull-ups. Port 1 also receives the low-order address byte during memory
programming and verification.
Alternate functions for Port 1 include:
12
40
I/O
T2 (P1.0): Timer/Counter 2 external count input/Clockout
23
41
I
T2EX (P1.1): Timer/Counter 2 Reload/Capture/Direction Control
P2.0-P2.7
21-28
24-31
18-25
I/O
Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 pins that
have 1s written to them are pulled high by the internal pull-ups and can be used as
inputs. As inputs, Port 2 pins that are externally pulled low will source current because
of the internal pull-ups. Port 2 emits the high-order address byte during fetches from
external program memory and during accesses to external data memory that use 16-
bit addresses (MOVX @DPTR).In this application, it uses strong internal pull-ups
emitting 1s. During accesses to external data memory that use 8-bit addresses (MOVX
@Ri), port 2 emits the contents of the P2 SFR. Some Port 2 pins receive the high order
address bits during EPROM programming and verification:
P2.0 to P2.5 for A8 to A13
P3.0-P3.7
10-17
11,
13-19
5,
7-13
I/O
Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that
have 1s written to them are pulled high by the internal pull-ups and can be used as
inputs. As inputs, Port 3 pins that are externally pulled low will source current because
of the internal pull-ups. Some Port 3 pin P3.4 receive the high order address bits during
EPROM programming and verification for TS8xC58X2 devices.
Port 3 also serves the special features of the 80C51 family, as listed below.
10
11
5
I
RXD (P3.0): Serial input port
11
13
7
O
TXD (P3.1): Serial output port
12
14
8
I
INT0 (P3.2): External interrupt 0
13
15
9
I
INT1 (P3.3): External interrupt 1
14
16
10
I
T0 (P3.4): Timer 0 external input
15
17
11
I
T1 (P3.5): Timer 1 external input
16
18
12
O
WR (P3.6): External data memory write strobe
17
19
13
O
RD (P3.7): External data memory read strobe
P3.4 also receives A14 during TS87C58X2 EPROM Programming.
Reset
9
10
4
I
Reset: A high on this pin for two machine cycles while the oscillator is running, resets
the device. An internal diffused resistor to VSS permits a power-on reset using only an
external capacitor to VCC.