AT8xC51SND2C
Table 7.
UART Signal Description
Signal
Name
RXD
Type
I/O
Description
Receive Serial Data
RXD sends and receives data in serial I/O mode 0 and receives data in
serial I/O modes 1, 2 and 3.
Transmit Serial Data
TXD outputs the shift clock in serial I/O mode 0 and transmits data in
serial I/O modes 1, 2 and 3.
Alternate
Function
P3.0
TXD
O
P3.1
Table 8.
SPI Controller Signal Description
Signal
Name
MISO
Type
I/O
Description
SPI Master Input Slave Output Data Line
When in master mode, MISO receives data from the slave peripheral.
When in slave mode, MISO outputs data to the master controller.
SPI Master Output Slave Input Data Line
When in master mode, MOSI outputs data to the slave peripheral.
When in slave mode, MOSI receives data from the master controller.
SPI Clock Line
When in master mode, SCK outputs clock to the slave peripheral. When
in slave mode, SCK receives clock from the master controller.
SPI Slave Select Line
When in controlled slave mode, SS enables the slave mode.
Alternate
Function
P4.0
MOSI
I/O
P4.1
SCK
I/O
P4.2
SS
I
P4.3
Table 9.
TWI Controller Signal Description
Signal
Name
Type
Description
TWI Serial Clock
When TWI controller is in master mode, SCL outputs the serial clock to
the slave peripherals. When TWI controller is in slave mode, SCL
receives clock from the master controller.
TWI Serial Data
SDA is the bidirectional Two Wire data line.
Alternate
Function
SCL
I/O
-
SDA
I/O
-
Table 10.
Keypad Interface Signal Description
Signal
Name
KIN0
Type
I
Description
Keypad Input Line
Holding this pin high or low for 24 oscillator periods triggers a keypad
interrupt.
Alternate
Function
-
7
4341D–MP3–04/05
ATMEL [ ATMEL CORPORATION ]
