ST6285BQ1 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
ST6285BQ1 Datasheet PDF : 78 Pages
| |||
ST62T85B/E85B
3.2 RESETS
The MCU can be reset in three ways:
The internal delay is generated by an on-chip coun-
– by the external Reset input being pulled low;
– by Power-on Reset;
– by the digital Watchdog peripheral timing out.
3.2.1 RESET Input
ter. The internal reset line is released 2048 internal
clock cycles after release of the external reset.
Notes:
To ensure correct start-up, the user should take
care that the reset signal is not released before the
The RESET pin may be connected to a device of VDD level is sufficient to allow MCU operation at
the application board in order to reset the MCU if the chosen frequency (see Recommended Oper-
required. The RESET pin may be pulled low in ating Conditions).
RUN, WAIT or STOP mode. This input can be
used to reset the MCU internal state and ensure a
correct start-up procedure. The pin is active low
and features a Schmitt trigger input. The internal
A proper reset signal for a slow rising VDD supply
can generally be provided by an external RC net-
work connected to the RESET pin.
Reset signal is generated by adding a delay to the
external signal. Therefore even short pulses on
Figure 10. Reset and Interrupt Processing
the RESET pin are acceptable, provided VDD has
completed its rising phase and that the oscillator is
) running correctly (normal RUN or WAIT modes).
t(s The MCU is kept in the Reset state as long as the
RESET pin is held low.
uc If RESET activation occurs in the RUN or WAIT
d modes, processing of the user program is stopped
ro (RUN mode only), the Inputs and Outputs are con-
figured as inputs with pull-up resistors and the
P main Oscillator is restarted. When the level on the
te RESET pin then goes high, the initialization se-
le quence is executed following expiry of the internal
o delay period.
s If RESET pin activation occurs in the STOP mode,
b the oscillator starts up and all Inputs and Outputs
O are configured as inputs with pull-up resistors.
- When the level of the RESET pin then goes high,
) the initialization sequence is executed following
t(s expiry of the internal delay period.
c 3.2.2 Power-on Reset
u The function of the POR circuit consists in waking
d up the MCU at an appropriate stage during the
ro power-on sequence. At the beginning of this se-
P quence, the MCU is configured in the Reset state:
all I/O ports are configured as inputs with pull-up
te resistors and no instruction is executed. When the
le power supply voltage rises to a sufficient level, the
o oscillator starts to operate, whereupon an internal
s delay is initiated, in order to allow the oscillator to
bfully stabilize before executing the first instruction.
OThe initialization sequence is executed immediate-
RESET
NMI MASK SET
INT LATCH CLEARED
( IF PRESENT )
SELECT
NMI MODE FLAGS
PUT FFEH
ON ADDRESS BUS
YES
IS RESET STILL
PRESENT?
NO
LOAD PC
FROM RESET LOCATIONS
FFE/FFF
FETCH INSTRUCTION
VA000427
ly following the internal delay.
20/78
20
Share Link: 