C509-L_97 Datasheet, PDF (13/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Introduction
C509-L
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
P9.0 - P9.7
XTAL2
XTAL1
*) I = Input
O = Output
Pin Number
74-77,
5-2
12
13
I/O*) Function
I/O Port 9
is an 8-bit bidirectional I/O port with internal pullup resi-
stors. Port 9 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 9 pins being externally
pulled low will source current (I _IL, in the DC characteri-
stics) because of the internal pullup resistors.
Port 9 can also be switched into a bidirectional mode, in
which CMOS levels are provided. In this bidirectional
mode, each port 1 pin can be programmed individually
as input or output.
Port 9 also serves alternate compare functions. The out-
put 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 9 as follows :
P9.0-P9.7 CC10-CC17 Compare/capture channel 0-7
output/input
– XTAL2
is the input to the inverting oscillator amplifier and input
to the internal clock generator circuits.
When supplying the C509-L with an external clock
source, XTAL2 should be driven, while XTAL1 is left
unconnected. A duty cycle of 0.45 to 0.55 of the clock
signal is required. Minimum and maximum high and low
times as well as rise/fall times specified in the AC
characteristics must be observed.
– XTAL1
Output of the inverting oscillator amplifier. This pin is
used for the oscillator operation with crystal or ceramic
resonartor
Semiconductor Group
1-6
1997-10-01