AT89C51CC01 Atmel Corporation, AT89C51CC01 Datasheet - Page 4

• Manufacturer Part Number: AT89C51CC01
• Manufacturer: Atmel Corporation

Specifications of AT89C51CC01

• Flash (kbytes): 32 Kbytes
• Max. Operating Frequency: 40 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Uart: 1
• Can: 1
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 62.5
• Sram (kbytes): 1.25
• Eeprom (bytes): 2048
• Self Program Memory: API
• Operating Voltage (vcc): 3.0 to 5.5
• Timers: 4
• Isp: UART/CAN
• Watchdog: Yes

I/O Configurations
Port 1, Port 3 and Port 4
Port 0 and Port 2
4
A/T89C51CC01
Each Port SFR operates via type-D latches, as illustrated in Figure 1 for Ports 3 and 4. A
CPU "write to latch" signal initiates transfer of internal bus data into the type-D latch. A
CPU "read latch" signal transfers the latched Q output onto the internal bus. Similarly, a
"read pin" signal transfers the logical level of the Port pin. Some Port data instructions
activate the "read latch" signal while others activate the "read pin" signal. Latch instruc-
tions are referred to as Read-Modify-Write instructions. Each I/O line may be
independently programmed as input or output.
Figure 1 shows the structure of Ports 1 and 3, which have internal pull-ups. An external
source can pull the pin low. Each Port pin can be configured either for general-purpose
I/O or for its alternate input output function.
To use a pin for general-purpose output, set or clear the corresponding bit in the Px reg-
ister (x = 1,3 or 4). To use a pin for general-purpose input, set the bit in the Px register.
This turns off the output FET drive.
To configure a pin for its alternate function, set the bit in the Px register. When the latch
is set, the "alternate output function" signal controls the output level (see Figure 1). The
operation of Ports 1, 3 and 4 is discussed further in the "quasi-Bidirectional Port Opera-
tion" section.
Figure 1. Port 1, Port 3 and Port 4 Structure
Note:
Ports 0 and 2 are used for general-purpose I/O or as the external address/data bus. Port
0, shown in Figure 3, differs from the other Ports in not having internal pull-ups. Figure 3
shows the structure of Port 2. An external source can pull a Port 2 pin low.
To use a pin for general-purpose output, set or clear the corresponding bit in the Px reg-
ister (x = 0 or 2). To use a pin for general-purpose input, set the bit in the Px register to
turn off the output driver FET.
READ
LATCH
INTERNAL
BUS
WRITE
TO
LATCH
The internal pull-up can be disabled on P1 when analog function is selected.
READ
PIN
D
CL
LATCH
P1.X
P3.X
P4.X
Q
ALTERNATE
OUTPUT
FUNCTION
ALTERNATE
INPUT
FUNCTION
VCC
INTERNAL
PULL-UP (1)
4129N–CAN–03/08
P1.x
P3.x
P4.x