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Rev. 1.10
44
March 02, 2020
Rev. 1.10
45
March 02, 2020
BS83A02L/BS83B04L
Ultra-Low Power Touch Key Flash MCU
BS83A02L/BS83B04L
Ultra-Low Power Touch Key Flash MCU
In the IDLE1 and IDLE2 Mode the high speed oscillator is on, if the peripheral function clock
source is derived from the high speed oscillator, the additional standby current will also be perhaps
in the order of several hundred micro-amps.
Wake-up
To minimise power consumption the devices can enter the SLEEP or any IDLE Mode, where the
CPU will be switched off. However, when the devices are woken up again, it will take a considerable
time for the original system oscillator to restart, stabilise and allow normal operation to resume.
After the system enters the SLEEP or IDLE Mode, it can be woken up from one of various sources
listed as follows:
•
An external falling edge on Port A
•
A system interrupt
•
A WDT overflow
When the devices execute the “HALT” instruction, the PDF flag will be set to 1. The PDF flag will
be cleared to 0 if the devices experience a system power-up or executes the clear Watchdog Timer
instruction. If the system is woken up by a WDT overflow, a Watchdog Timer reset will be initiated
and the TO flag will be set to 1. The TO flag is set if a WDT time-out occurs and causes a wake-up
that only resets the Program Counter and Stack Pointer, other flags remain in their original status.
Each pin on Port A can be setup using the PAWU register to permit a negative transition on the pin
to wake up the system. When a Port A pin wake-up occurs, the program will resume execution at
the instruction following the “HALT” instruction. If the system is woken up by an interrupt, then
two possible situations may occur. The first is where the related interrupt is disabled or the interrupt
is enabled but the stack is full, in which case the program will resume execution at the instruction
following the “HALT” instruction. In this situation, the interrupt which woke up the devices will not
be immediately serviced, but will rather be serviced later when the related interrupt is finally enabled
or when a stack level becomes free. The other situation is where the related interrupt is enabled and
the stack is not full, in which case the regular interrupt response takes place. If an interrupt request
flag is set high before entering the SLEEP or IDLE Mode, the wake-up function of the related
interrupt will be disabled.