SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 375

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

20
The internal system reset function provides initialization of the C164CM into a defined
default state. The default state is invoked either by asserting a hardware reset signal on
pin RSTIN (Hardware Reset Input), by executing the SRST instruction (Software Reset),
or by an overflow of the watchdog timer.
Whenever one of these conditions occurs, the microcontroller is reset into its predefined
default state through an internal reset procedure. When a reset is initiated, pending
internal hold states are cancelled and the current internal access cycle (if any) is
completed. An external bus cycle is aborted, except for a watchdog reset (see
description). Afterwards, the bus pin drivers and the IO pin drivers are switched off
(tristate).
The internal reset procedure requires 516 CPU clock cycles in order to perform a
complete reset sequence. This 516 cycle reset sequence is started by a watchdog timer
overflow, by an SRST instruction or when the reset input signal RSTIN is latched low
(hardware reset). The internal reset condition is active for at least the duration of the
reset sequence and then until the RSTIN input is inactive and the PLL has locked (if the
PLL is selected for the basic clock generation). When this internal reset condition is
removed (reset sequence complete, RSTIN inactive, PLL locked), the reset
configuration is latched from PORT0, RD, and ALE (depending on the start mode).
Afterwards, pins ALE, RD, and WR are driven to their inactive levels.
Note: Bit ADP (which selects the Adapt mode) is latched with the rising edge of RSTIN.
After the internal reset condition is removed, the microcontroller will either start program
execution from external or internal memory, or it will enter boot mode.
Figure 20-1 External Reset Circuitry
User’s Manual
System Reset
Reset
V
DD
RSTOUT
RSTIN
+
20-1
b)
a) Generated Warm Reset
b) Automatic Power-ON Reset
a)
&
Hardware
External
External
Reset
Sources
MCA04483
C164CM/C164SM
System Reset
Derivatives
V1.0, 2002-02