SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 386

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

20.4
Although most of the programmable features of the C164CM are selected by software
either during the initialization phase or repeatedly during program execution, some
features must be selected earlier because they are used for the first access of the
program execution (for example, internal or external start selected via EA).
These configurations are accomplished by latching the logic levels at a number of pins
at the end of the internal reset sequence. During reset, internal pull-up/pull-down devices
are active on those lines. They ensure inactive/default levels at pins which are not driven
externally. External pull-down/pull-up devices may override the default levels in order to
select a specific configuration. Many configurations can, therefore, be coded with a
minimum of external circuitry.
Note: The load on those pins to be latched for configuration must be small enough for
User’s Manual
the internal pull-up/pull-down device to sustain the default level, or external pull-
up/pull-down devices must ensure this level.
Those pins whose default level will be overridden must be pulled low/high
externally.
Ensure that the valid target levels are reached by the end of the reset sequence.
There is a specific application note to illustrate this.
System Startup Configuration
20-12
C164CM/C164SM
System Reset
Derivatives
V1.0, 2002-02