C515C Datasheet, PDF (10/69 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

C515C
Table 1
Pin Definitions and Functions (cont’d)
Symbol
XTAL2
XTAL1
P2.0-P2.7
CPUR
*) I = Input
O = Output
Pin Number
P-MQFP-80
36
37
38-45
46
I/O*) Function
I
XTAL2
Input to the inverting oscillator amplifier and input to the
internal clock generator circuits.
To drive the device from an external clock source, XTAL2
should be driven, while XTAL1 is left unconnected.
Minimum and maximum high and low times as well as
rise/fall times specified in the AC characteristics must be
observed.
O XTAL1
Output of the inverting oscillator amplifier.
I/O Port 2
is an 8-bit quasi-bidirectional I/O port with internal pullup
resistors. Port 2 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 2 pins being
externally pulled low will source current (I _IL, in the DC
characteristics) because of the internal pullup resistors.
Port 2 emits the high-order address byte during fetches
from external program memory and during accesses to
external data memory that use 16-bit addresses
(MOVX @DPTR). In this application it uses strong
internal pullup resistors when issuing 1's. During
accesses to external data memory that use 8-bit
addresses (MOVX @Ri), port 2 issues the contents of
the P2 special function register.
O CPU running condition
This output pin is at low level when the CPU is running
and program fetches or data accesses in the external
data memory area are executed. In idle mode, hardware
and software power down mode, and with an active
RESET signal CPUR is set to high level.
CPUR can be typically used for switching external
memory devices into power saving modes.
Semiconductor Group
10
1997-07-01