AT89C51ID2-SLSIM Atmel, AT89C51ID2-SLSIM Datasheet - Page 12

• Manufacturer Part Number: AT89C51ID2-SLSIM
• Description: C51ID2 64KF TWI 32KHZ PLCC44 3-5.5V IND.
• Manufacturer: Atmel

Table 15. Pin Description (Continued)
4289C–8051–11/05
XTALA1
XTALA2
XTALB1
XTALB2
P2.0 - P2.7
P3.0 - P3.7
P4.0 - P4.7
P5.0 - P5.7
PI2.0 - PI2.1
Mnemonic
PLCC44
24 - 31
13 - 19
34, 12
11,
21
20
13
14
15
16
17
18
19
34
11
2
1
-
-
Pin Number
VQFP44
18 - 25
7 - 13
28, 6
15
14
40
39
10
12
13
28
11
5,
5
7
8
9
-
-
Type
I/O
I/O
I/O
I/O
I/O
I/O
O
O
O
O
O
I
I
I
I
I
I
I
Name and Function
MOSI: SPI Master Output Slave Input line
When SPI is in master mode, MOSI outputs data to the slave peripheral. When SPI is in
slave mode, MOSI receives data from the master controller.
Crystal A 1: Input to the inverting oscillator amplifier and input to the internal clock genera-
tor circuits.
Crystal A 2: Output from the inverting oscillator amplifier
Crystal B 1: (Sub Clock) Input to the inverting oscillator amplifier and input to the internal
clock generator circuits.
Crystal B 2: (Sub Clock) Output from the inverting oscillator amplifier
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.
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. 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
INT0 (P3.2): External interrupt 0
INT1 (P3.3): External interrupt 1
T0 (P3.4): Timer 0 external input
T1 (P3.5): Timer 1 external input
WR (P3.6): External data memory write strobe
RD (P3.7): External data memory read strobe
Port 4: Port 4 is an 8-bit bidirectional I/O port with internal pull-ups. Port 5 pins that have 1s
written to them are pulled high by the internal pull-ups and can be used as inputs. As
inputs, Port 4 pins that are externally pulled low will source current because of the internal
pull-ups.
Port 5: Port 5 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 5 pins that are externally pulled low will source current because of the internal
pull-ups.
Port I2: Port I2 is an open drain. It can be used as inputs (must be polarized to Vcc with
external resistor to prevent any parasitic current consumption).
SCL (PI2.0): 2-wire Serial Clock
SCL output the serial clock to slave peripherals
SCL input the serial clock from master
AT89C51ID2
12