C517A_99 Datasheet, PDF (14/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Introduction
C517A
Table 1-1
Pin Definitions and Functions (cont’d)
6\PERO
V_SS
3LQ 1XPEHU
304)3 3/&&
10, 62
37, 83
V_DD
XTAL2
11, 63
12
38, 84
39
XTAL1
13
40
P2.0 - P2.7 14 - 21
41 - 48
*) I = Input
O = Output
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– Ground (0V)
during normal, idle, and power down
operation.
– Supply voltage
during normal, idle, and power down mode.
– XTAL2
is the 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.
– XTAL1
is the output of the inverting oscillator
amplifier. This pin is used for the oscillator
operation with crystal or ceramic resonator.
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.
Semiconductor Group
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