Signal
Name
Alternate
Function
Type Description
OCLK
DCLK
DDAT
DSEL
Port 4
P4.6:0
I/O
P4 is a 7-bit bidirectional I/O port with internal pull-ups.
NFCE1/SMLCK
NFCE2/SMINS
NFCE3/SMCE
LRD/LDE
SDR
LCS
SCS
Port 5
P5.3:0
I/O
P5 is a 4-bit bidirectional I/O port with internal pull-ups.
LA0/LRS
SA0
LWR/LRW
SWR
Table 3. Timer 0 and Timer 1 Signal Description
Signal
Name
Alternate
Function
Type Description
Timer 0 Gate Input
INT0 serves as external run control for timer 0, when selected by
GATE0 bit in TCON register.
P3.2
RTS
SCK
INT0
I
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.
Timer 1 Gate Input
INT1 serves as external run control for timer 1, when selected by
GATE1 bit in TCON register.
P3.3
CTS
SS
INT1
T0
I
I
External Interrupt 1
INT1 input sets IE1 in the TCON register. If bit IT1 in this register is set,
bit IE1 is set by a falling edge on INT1. If bit IT1 is cleared, bit IE1 is set
by a low level on INT1.
Timer 0 External Clock Input
When timer 0 operates as a counter, a falling edge on the T0 pin
increments the count.
P3.4
8
AT85C51SND3Bx
7632A–MP3–03/06
ATMEL [ ATMEL ]
