AT80C51RA2 データシートの表示（PDF） - Atmel Corporation
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AT80C51RA2 Datasheet PDF : 86 Pages
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Mnemonic
VSS
Vss1
VCC
P0.0-P0.7
P1.0-P1.7
P2.0-P2.7
P3.0-P3.7
Pin Number
DIL LCC VQFP 1.4
20
22
16
1
39
40
44
38
39-32 43-36
37-30
1-8
2-9
40-44
1-3
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
21-28 24-31
40
41
42
43
44
45
46
47
18-25
10-17 11,
13-19
5,
7-13
10
11
5
11
13
7
Type
I
I
I
I/O
I/O
I/O
I
I
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
O
Name And Function
Ground: 0V reference
Optional Ground: Contact the Sales Office for ground connection.
Power Supply: This is the power supply voltage for normal, idle and power-down
operation
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.
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:
T2 (P1.0): Timer/Counter 2 external count input/Clockout
T2EX (P1.1): Timer/Counter 2 Reload/Capture/Direction Control
ECI (P1.2): External Clock for the PCA
CEX0 (P1.3): Capture/Compare External I/O for PCA module 0
CEX1 (P1.4): Capture/Compare External I/O for PCA module 1
CEX0 (P1.5): Capture/Compare External I/O for PCA module 2
CEX0 (P1.6): Capture/Compare External I/O for PCA module 3
CEX0 (P1.7): Capture/Compare External I/O for PCA module 4
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 (P2.0 to P2.5) receive
the high order address bits during EPROM programming and verification:
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 pins (P3.4 to P3.5) receive the high order address
bits during EPROM programming and verification.
Port 3 also serves the special features of the 80C51 family, as listed below.
RXD (P3.0): Serial input port
TXD (P3.1): Serial output port
8 AT/TS8xC51Rx2
4188F–8051–01/08
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