C505_9708 SIEMENS [Siemens Semiconductor Group], C505_9708 Datasheet - Page 15

• Manufacturer Part Number: C505_9708
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Table 1-1
Pin Definitions and Functions
Symbol
EA
P0.0-P0.7
V
V
V
V
*) I = Input
Semiconductor Group
AREF
AGND
SS
CC
O = Output
Pin Number
29
37-30
38
39
16
17
I/O*)
I
I/O
–
–
–
–
Function
External Access Enable
When held at high level, instructions are fetched from the
internal ROM when the PC is less than 4000
at low level, the C505 fetches all instructions from external
program memory. This pin should not be driven during reset
operation.
For the C505-L and the C505C-L this pin must be tied low.
Port 0
is an 8-bit open-drain bidirectional I/O port. Port 0 pins that
have 1’s written to them float, and in that state can be used
as high-impendance inputs. Port 0 is also the multiplexed
low-order address and data bus during accesses to external
program or data memory. In this application it uses strong
internal pullup transistors when issuing 1’s.
Port 0 also outputs the code bytes during program
verification in the C505C-2R. External pullup resistors are
required during program verification.
Reference voltage for the A/D converter.
Reference ground for the A/D converter.
Ground (0V)
Power Supply (+ 5 V)
1-9
C505 / C505C
Introduction
H
. When held
1997-08-01