Specifications

5
AT83SND2CMP3
7524D–MP3–07/07
Signals All the AT83SND2CMP3 signals are detailed by functionality in following tables.
Table 1. Ports Signal Description
Table 2. Clock Signal Description
Table 3. Timer 0 and Timer 1 Signal Description
Signal
Name Type Description
Alternate
Function
P0.7:0 I/O
Port 0
P0 is an 8-bit open-drain bidirectional I/O port. Port 0 pins that have 1s
written to them float and can be used as high impedance inputs. To
avoid any parasitic current consumption, floating P0 inputs must be
polarized to V
DD
or V
SS
.
AD7:0
P2.7:0 I/O
Port 2
P2 is an 8-bit bidirectional I/O port with internal pull-ups.
A15:8
P3.7:0 I/O
Port 3
P3 is an 8-bit bidirectional I/O port with internal pull-ups.
RXD
TXD
INT0
INT1
T0
T1
WR
RD
P4.3:0 I/O
Port 4
P4 is an 8-bit bidirectional I/O port with internal pull-ups.
Signal
Name Type Description
Alternate
Function
X1 I
Input to the on-chip inverting oscillator amplifier
To use the internal oscillator, a crystal/resonator circuit is connected to
this pin. If an external oscillator is used, its output is connected to this
pin. X1 is the clock source for internal timing.
-
X2 O
Output of the on-chip inverting oscillator amplifier
To use the internal oscillator, a crystal/resonator circuit is connected to
this pin. If an external oscillator is used, leave X2 unconnected.
-
FILT I
PLL Low Pass Filter input
FILT receives the RC network of the PLL low pass filter.
-
Signal
Name Type Description
Alternate
Function
INT0 I
Timer 0 Gate Input
INT0 serves as external run control for timer 0, when selected by
GATE0 bit in TCON register.
External Interrupt 0
INT0 input sets IE0 in the TCON register. If bit IT0 in this register is set,
bit IE0 is set by a falling edge on INT0#. If bit IT0 is cleared, bit IE0 is
set by a low level on INT0#.
P3.2