ST6200 STMICROELECTRONICS [STMicroelectronics], ST6200 Datasheet - Page 23

• Manufacturer Part Number: ST6200
• Description: 8-BIT MCUs WITH A/D CONVERTER, TWO TIMERS, OSCILLATOR SAFEGUARD & SAFE RESET
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

5.3 RESET
5.3.1 Introduction
The MCU can be reset in three ways:
5.3.2 RESET Sequence
The basic RESET sequence consists of 3 main
phases:
The reset delay allows the oscillator to stabilise
and ensures that recovery has taken place from
the Reset state.
Figure 13. RESET Sequence
A low pulse input on the RESET pin
Internal Watchdog reset
Internal Low Voltage Detector (LVD) reset
Internal (watchdog or LVD) or external Reset
event
A delay of 2048 or 32768 clock (f
(selected through the option bytes)
RESET vector fetch
WATCHDOG
RESET PIN
INTERNAL
RESET
RESET
RESET
LVD
V
V
IT+
IT-
V
RUN
DD
RESET
INT
) cycles
RUN
RESET
WATCHDOG UNDERFLOW
The RESET vector fetch phase duration is 2 clock
cycles.
When a reset occurs:
– The stack is cleared
– The PC is loaded with the address of the Reset
A jump to the beginning of the user program must
be coded at this address.
– The interrupt flag is automatically set, so that the
vector. It is located in program ROM starting at
address 0FFEh.
CPU is in Non Maskable Interrupt mode. This
prevents the initialization routine from being in-
terrupted. The initialization routine should there-
fore be terminated by a RETI instruction, in order
to go back to normal mode.
RUN
RESET
ST6200C/ST6201C/ST6203C
2048 CLOCK CYCLE (f INT ) DELAY
RUN
23/100
1