ST6208C/ST6209C/ST6210C/ST6220C
6.3 STOP MODE
STOP mode is the lowest power consumption
mode of the MCU (see Figure 22).
The Program Counter then points to the starting
address of the interrupt or RESET service routine
(see Figure 21).
The MCU goes into STOP mode as soon as the
STOP instruction is executed. This has the follow-
ing effects:
STOP Mode and Watchdog
When the Watchdog is active (hardware or soft-
ware activation), the STOP instruction is disabled
and a WAIT instruction will be executed in its place
unless the EXCTNL option bit is set to 1 in the op-
tion bytes and a a high level is present on the NMI
pin. In this case, the STOP instruction will be exe-
cuted and the Watchdog will be frozen.
– Program execution is stopped, the microcontrol-
ler can be considered as being “frozen”.
– The contents of RAM and the peripheral regis-
ters are kept safely as long as the power supply
voltage is higher than the RAM retention voltage.
– The oscillator is stopped, so peripherals cannot
work except the those that can be driven by an
external clock.
Figure 21. STOP Mode Timing Overview
2048
Exit from STOP Mode
CLOCKCYCLE
RUN
STOP
RUN
DELAY
The MCU remains in STOP mode until one of the
following events occurs:
– RESET (Watchdog, LVD or RESET pin)
STOP
INSTRUCTION
– A peripheral interrupt (assuming this peripheral
can be driven by an external clock)
– An external interrupt (I/O port, NMI)
In all cases a delay of 2048 clock cycles (fINT) is
generated to make sure the oscillator has started
properly.
RESET
OR
INTERRUPT
FETCH
VECTOR
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