C515C Datasheet, PDF (12/69 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

C515C
Table 1
Pin Definitions and Functions (cont’d)
Symbol
HWPD
P4.0-P4.7
PE/SWD
*) I = Input
O = Output
Pin Number
P-MQFP-80
69
72-74, 76-80
72
73
74
76
77
78
79
80
75
I/O*) Function
I
Hardware Power Down
A low level on this pin for the duration of one machine
cycle while the oscillator is running resets the C515C.
A low level for a longer period will force the part to power
down mode with the pins floating.
I/O Port 4
is an 8-bit quasi-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.
P4 also contains the external A/D converter control pin,
the SSC pins, the CAN controller input/output lines, and
the external interrupt 8 input. The output latch
corresponding to a secondary functionmust be
programmed to a one (1) for that function to operate.
The alternate functions are assigned to port 4 as follows:
P4.0 ADST External A/D converter start pin
P4.1 SCLK SSC Master Clock Output /
SSC Slave Clock Input
P4.2 SRI
SSC Receive Input
P4.3 STO SSC Transmit Output
P4.4 SLS Slave Select Input
P4.5 INT8 External interrupt 8 input
P4.6 TXDC Transmitter output of the CAN controller
P4.7 RXDC Receiver input of the CAN controller
I
Power saving mode enable / Start watchdog timer
A low level on this pin allows the software to enter the
power down, idle and slow down mode. In case the low
level is also seen during reset, the watchdog timer
function is off on default.
Use 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 pull-up resistor.
Semiconductor Group
12
1997-07-01