C509-L_97 Datasheet, PDF (15/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Introduction
C509-L
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
P0.0 – P0.7
HWPD
P5.0 - P5.7
*) I = Input
O = Output
Pin Number
26, 27,
30-35
36
44-37
I/O*) Function
I/O Port 0
is an 8-bit open-drain bidirectional I/O port. Port 0 pins
that have 1s written to them float, and in that state can be
used as high-impendance inputs. Port 0 is also the
multiplexed low-order address and data bus during
accesses to external program or data memory. In this
operating mode it uses strong internal pullup resistors
when issuing 1 s.
P0.0 - P0.7 AD0-AD7 Address/data lines 0 - 7
I
Hardware Power Down
A low level on this pin for the duration of one machine
cycle while the oscillator is running resets the C509-L.
A low level for a longer period will force the part to power
down mode with the pins floating. There is no internal
pullup resistor connected to this pin.
I/O Port 5
is an 8-bit bidirectional I/O port with internal pullup
resistors. Port 5 pins that have 1's written to them are
pulled high by the internal pullup resistors, and in that
state can be used as inputs. As inputs, port 5 pins being
externally pulled low will source current (I _IL, in the DC
characteristics) because of the internal pullup resistors.
Port 5 can also be switched into a bidirectional mode, in
which CMOS levels are provided. In this bidirectional
mode, each port 5 pin can be programmed individually
as input or output.
Port 5 also serves as alternate function for “Concurrent
Compare” and "Set/Reset compare” functions. 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
5 as follows :
P5.0 - P5.7 CCM0-CCM7 Concurrent Compare
or Set/Reset lines 0 - 7
Semiconductor Group
1-8
1997-10-01