C501_1 Datasheet, PDF (93/121 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller

Power Saving Modes
C501
8.4 State of Pins in Software Initiated Power Saving Modes
In the idle mode and in the power down mode the port pins of the C501 have a well defined status
which is listed in the following table 8-10. This state of some pins also depends on the location of
the code memory (internal or external).
Table 8-10 :
Status of External Pins During Idle and Software Power Down Mode
Outputs
ALE
PSEN
PORT 0
PORT 1
PORT 2
PORT 3
Last Instruction Executed from
Internal Code Memory
Idle
Power Down
High
Low
High
Low
Data
Data
Data
Data
Data
Data
Data/alternate
outputs
Data/last output
Last Instruction Executed from
External Code Memory
Idle
Power Down
High
Low
High
Low
Data
Float
Data
Data
Address
Data
Data/alternate
outputs
Data/last output
Semiconductor Group
8-4