C505-2RM SIEMENS [Siemens Semiconductor Group], C505-2RM Datasheet - Page 9

• Manufacturer Part Number: C505-2RM
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Table 3
Pin Definitions and Functions (cont’d)
Symbol
RESET
P3.0-P3.7
*) I = Input
Semiconductor Group
O = Output
Pin Number
4
5, 7-13
5
7
8
9
10
11
12
13
*)
I
I/O
I/O
Function
RESET
A high level on this pin for one machine cycle while the
oscillator is running resets the device. An internal diffused
resistor to
external capacitor to
Port 3
is an 8-bit quasi-bidirectional port with internal pull-up
arrangement. Port 3 pins that have 1’s written to them are
pulled high by the internal pull-up transistors and in that
state can be used as inputs. As inputs, port 3 pins being
externally pulled low will source current (
characteristics) because of the internal pullup transistors.
The output latch corresponding to a secondary function
must be programmed to a one (1) for that function to operate
(except for TxD and WR). The secondary functions are
assigned to the pins of port 3 as follows:
P3.0 / RxD
P3.1 / TxD
P3.2 / INT0
P3.3 / INT1
P3.4 / T0
P3.5 / T1
P3.6 / WR
P3.7 / RD
9
V
SS
permits power-on reset using only an
Receiver data input (asynch.) or data
input/output (synch.) of serial interface
Transmitter data output (asynch.) or
clock output (synch.) of serial interface
External interrupt 0 input / timer 0 gate
control input
External interrupt 1 input / timer 1 gate
control input
Timer 0 counter input
Timer 1 counter input
WR control output; latches the data
byte from port 0 into the external data
memory
RD control output; enables the external
data memory
V
CC
.
C505A / C505CA
C505 / C505C
I
IL
, in the DC
1997-12-01