SAKC505C-LM 查看數據表（PDF） - Siemens AG

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SAKC505C-LM

8-Bit CMOS Microcontroller

Siemens AG 

C505 / C505C

C505A / C505CA

Table 3

Pin Definitions and Functions (cont’d)

Symbol

EA

Pin Number I/O

*)

29

I

P0.0-P0.7 37-30

I/O

VAREF

38

–

VAGND

39

–

VSS

16

–

VCC

17

–

*) I = Input

O = Output

Function

External Access Enable

When held at high level, instructions are fetched from the

internal ROM or OTP memory when the PC is less than

4000H (C505 and C505C) or less than 8000H (C505A and

C505CA). When held at low level, the C505 fetches all

instructions from external program memory. EA 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 C505-2R/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 (0 V)

Power Supply (+ 5 V)

Semiconductor Group

12

1997-12-01

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