C517A_99 Datasheet, PDF (16/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Introduction
C517A
Table 1-1
Pin Definitions and Functions (cont’d)
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HWPD
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36
60
P5.0 - P5.7 44 - 37
68 - 61
OWE
45
69
*) I = Input
O = Output
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I
Hardware Power Down
A low level on this pin for the duration of one
machine cycle while the oscillator is running
resets the C517A. A low level for a longer
period will force the part into hardware
power down mode with the pins floating.
There is no internal pullup resistor
connected to this pin.
I/O Port 5
is a quasi-bidirectional I/O port with internal
pull-up resistors. Port 5 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 5 pins
being externally pulled low will source
current (I_IL, in the DC characteristics)
because of the internal pull-up resistors.
This port also serves the alternate function
"Concurrent Compare" and "Set/Reset
Compare". The secondary functions are
assigned to the port 5 pins as follows:
CCM0 to CCM7 P5.0 to P5.7 :
concurrent compare or
Set/Reset lines
I
Oscillator Watchdog Enable
A high level on this pin enables the oscillator
watchdog. When left unconnected this pin is
pulled high by a weak internal pull-up
resisitor. The logic level at OWE should not
be changed during normal operation. When
held at low level the oscillator watchdog
function is turned off. During hardware
power down the pullup resistor is switched
off.
Semiconductor Group
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