Datasheet

C515C
Data Sheet 9 2003-02
XTAL1 37 O XTAL1
Output of the inverting oscillator amplifier.
P2.0-P2.7 38-45 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.
CPUR
46 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.
PSEN
47 O The Program Store Enable
output is a control signal that enables the external
program memory to the bus during external fetch
operations. It is activated every six oscillator
periods, except during external data memory
accesses. The signal remains high during internal
program execution.
Table 2 Pin Definitions and Functions (cont’d)
Symbol Pin Number I/O
1)
Function
P-MQFP-80-1