User guide

17
SmartBook for Renesas R8C/Tiny Microcontrollers
www.MightyMicons.com
Like wait mode, to exit from this stop
mode, a hardware reset or a peripheral
function interrupt is required. Only the
peripheral functions already enabled
before entering into stop mode can be
used to bring the micon from the stop mode.
Since all the peripheral clocks are already
stopped, these peripheral functions should use
the external signals to interrupt the micon.
When the stop mode is interrupted to bring the
micon into other operating modes, the CPU operating
system clock always gets divide by 8 clock from either
the main clock or the ring oscillator.
2.9 System Reset:
Reset facility of any microcontroller is an important mechanism to monitor and
safeguard the workings of the controllers within the defined operating environment.
It should also prevent the controller from going into any unknown state when the
operating environment is disturbed. To make any application reliable and trouble
free, a suitable reset management circuit should be included into the design. In
the simple designs, an external watchdog timer is used to monitor the operating
conditions and force the controller into reset state when the supply voltage goes
down below a reference voltage. Also, when the watch dog timer does not receive
the periodic system health signal from the controller within the underflow time,
this timer forces the microcontrollers into reset state to execute the defined program
flow. This way controller can be protected from executing anything unwanted.
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These devices also
contain a power on
reset function
without any
external device to
bring up the
hardware in an orderly manner.
Whenever the operating voltage
crosses this Vdet, the voltage
detector generates an interrupt
and also the reset
condition can be
activated.