SAB80C517A-N18 Siemens Semiconductor Group, SAB80C517A-N18 Datasheet - Page 10

• Manufacturer Part Number: SAB80C517A-N18
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: Siemens Semiconductor Group

Pin Definitions and Functions (cont’d)
Symbol
P3.0 - P3.7 21 - 28
*
Semiconductor Group
I = Input
O = Output
P-LCC-84
Pin Number
P-MQFP-100-2
90 - 97
I/O
I/O
9
*)
Function
Port 3
is a bidirectional I/O port with internal pull-
up resistors. Port 3 pins that have 1 s
written to them are pulled high by the
internal pull-up resistors, and in that state
can be used as inputs. As inputs, port 3
pins being externally pulled low will source
current ( I
because of the internal pull-up resistors.
Port 3 also contains the interrupt, timer,
serial port 0 and external memory strobe
pins that are used by various options. The
output latch corresponding to a secondary
function must be programmed to a one (1)
for that function to operate.
The secondary functions are assigned to
the pins of port 3, as follows:
– R D0 (P3.0): receiver data input
– T D0 (P3.1): transmitter data output
– INT0 (P3.2):
– T0 (P3.4):
– T1 (P3.5):
– WR (P3.6):
– RD (P3.7):
– INT1 (P3.3):
(asynchronous) or data input/output
(synchronous) of serial interface
(asynchronous) or clock output
(synchronous) of serial interface 0
gate control
gate control
latches the data byte from port 0 into the
external data memory
enables the external data memory to
port 0
IL,
SAB 80C517A/83C517A-5
in the DC characteristics)
interrupt 0 input/timer 0
interrupt 1 input/timer 1
counter 0 input
counter 1 input
the write control signal
the read control signal
1994-05-01