C509-L_97 Datasheet, PDF (16/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Introduction
C509-L
Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
OWE
P6.0 - P6.7
*) I = Input
O = Output
Pin Number
45
46-50,
54-56
46
47
48
49
I/O*) Function
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 pullup resistor. 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.
I/O Port 6
is an 8-bit bidirectional I/O port with internal pullup
resistors. Port 6 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 6 pins being
externally pulled low will source current (I _IL, in the DC
characteristics) because of the internal pullup resistors.
Port 6 can also be switched into a bidirectional mode, in
which CMOS levels are provided. In this bidirectional
mode, each port 6 pin can be programmed individually
as input or output.
Port 6 also contains the external A/D converter control
pin, the receive and transmission lines for the serial
port 1, and the write-FLASH control signal. 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 6 as follows :
P6.0 ADST External A/D converter start pin
P6.1 R×D1 Receiver data input of serial interface 1
P6.2 T×D1 Transmitter data output of serial
interface 1
P6.3 WRF The WRF (write Flash) signal is active
when the programming mode is
selected. In this mode WRF becomes
active when executing external data
memory write (MOVX) instructions.
Semiconductor Group
1-9
1997-10-01