C509-L_97 Datasheet, PDF (17/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Introduction
C509-L
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
P8.0 - P8.6
RO
P4.0 – P4.7
PE / SWD
*) I = Input
O = Output
Pin Number
57-60,
51-53
61
64-66,
68-72
67
I/O*) Function
I
Port 8
is a 7-bit unidirectional input port. Port pins can be used
for digital input if voltage levels meet the specified input
high/low voltages, and for the higher 7-bit of the
multiplexed analog inputs of the A/D converter
simultaneously.
P8.0 - P8.6 AIN8 - AIN14 Analog input 8 - 14
O Reset Output
This pin outputs the internally synchronized reset
request signal. This signal may be generated by an
external hardware reset, a watchdog timer reset or an
oscillator watchdog reset. The RO output is active low.
I/O Port 4
is an 8-bit bidirectional I/O port with internal pull-up
resistors. Port 4 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 4 pins being
externally pulled low will source current (I _IL, in the DC
characteristics) because of the internal pull-up resistors.
Port 4 also erves as alternate compare functions. The
output latch corresponding to a secondary functionmust
be programmed to a one (1) for that function to operate.
The secondary functions are assigned to the pins of port
4 as follows :
P4.0 - P4.7 CM0 - CM7 Compare channel 0 - 7
I
Power Saving Modes Enable / Start Watchdog Timer
A low level on this pin allows the software to enter the
power down mode, idle and slow down mode. If the low
level is also seen during reset, the watchdog timer
function is off on default.
Usage of the software controlled power saving modes is
blocked, when this pin is held on high level. A high level
during reset performs an automatic start of the watchdog
timer immediately after reset.
When left unconnected this pin is pulled high by a weak
internal pullup resistor. During hardware power down the
pullup resistor is switched off.
Semiconductor Group
1-10
1997-10-01