SAB80515 Datasheet, PDF (223/270 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller Family

Device Specifications
Pin Definitions and Functions (cont’d)
Symbol Pin
Pin
Input (I) Function
P-LCC-68 P-MQFP-80 Output (O)
XTAL2 39
36
XTAL1 40
37
P2.0-P2.7 41-48
38-45
I/O
XTAL2
Input to the inverting oscillator amplifier
and input to the internal clock generator
circuits.
XTAL1
Output of the inverting oscillator amplifier.
To drive the device from an external clock
source, XTAL2 should be driven, while
XTAL1 is left unconnected. There are no
requirements on the duty cycle of the
external clock signal, since the input to the
internal clocking circuitry is divided down
by a divide-by-two flip-flop. Minimum and
maximum high and low times and rise/fall
times specified in the AC characteristics
must be observed.
Port 2
is an 8-bit 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 _{I L,} 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.
Semiconductor Group
223