AT89C51RD2 Atmel Corporation, AT89C51RD2 Datasheet - Page 11

• Manufacturer Part Number: AT89C51RD2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RD2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 32
• Spi: 1
• Uart: 1
• Sram (kbytes): 2
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

Table 4-1.
4235K–8051–05/08
V
V
P0.0 - P0.7
P1.0 - P1.7
Mnemonic
SS
CC
Pin Description
PLCC44 VQFP44
43 - 36
2 - 9
22
44
2
3
4
5
6
7
8
37 - 30
40 - 44
1 - 3
16
38
40
41
42
43
44
1
2
Pin Number
PLCC68
9,6, 5, 3
15, 14,
12, 11,
19, 21,
22, 23,
25, 27,
28, 29
51
17
19
21
22
23
25
27
28
6, 5, 3, 2,
VQFP64
61,60,59
10, 12,
13, 14,
16, 18,
19, 20
64,
40
10
12
13
14
16
18
19
8
Type
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
I
I
I
I
Name and Function
Ground: 0V reference
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 must be polarized to V
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 AT89C51RD2/ED2 Port 1 include:
P1.0: Input/Output
T2 (P1.0): Timer/Counter 2 external count input/Clockout
P1.1: Input/Output
T2EX: Timer/Counter 2 Reload/Capture/Direction Control
SS: SPI Slave Select
P1.2: Input/Output
ECI: External Clock for the PCA
P1.3: Input/Output
CEX0: Capture/Compare External I/O for PCA module 0
P1.4: Input/Output
CEX1: Capture/Compare External I/O for PCA module 1
P1.5: Input/Output
CEX2: Capture/Compare External I/O for PCA module 2
MISO: SPI Master Input Slave Output line
When SPI is in master mode, MISO receives data from the slave
peripheral. When SPI is in slave mode, MISO outputs data to the master
controller.
P1.6: Input/Output
CEX3: Capture/Compare External I/O for PCA module 3
SCK: SPI Serial Clock
CC
AT89C51RD2/ED2
or V
SS
in order to prevent any parasitic
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