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Rev. 1.10
42
March 02, 2020
Rev. 1.10
43
March 02, 2020
BS83A02L/BS83B04L
Ultra-Low Power Touch Key Flash MCU
BS83A02L/BS83B04L
Ultra-Low Power Touch Key Flash MCU
the f
SUB
clock will be on.
•
The Data Memory contents and registers will maintain their present condition.
•
The I/O ports will maintain their present conditions.
•
In the status register, the Power Down flag, PDF, will be set and the Watchdog time-out flag, TO,
will be cleared.
•
The WDT will be cleared and resume counting as the WDT function is always enabled.
Entering the IDLE1 Mode
There is only one way for the device to enter the IDLE1 Mode and that is to execute the “HALT”
instruction in the application program with both the FHIDEN and FSIDEN bits in the SCC register
equal to “1”. When this instruction is executed under the conditions described above, the following
will occur:
•
The f
H
and f
SUB
clocks will be on but the application program will stop at the “HALT” instruction.
•
The Data Memory contents and registers will maintain their present condition.
•
The I/O ports will maintain their present conditions.
•
In the status register, the Power Down flag, PDF, will be set and the Watchdog time-out flag, TO,
will be cleared.
•
The WDT will be cleared and resume counting as the WDT function is always enabled.
Entering the IDLE2 Mode
There is only one way for the device to enter the IDLE2 Mode and that is to execute the “HALT”
instruction in the application program with the FHIDEN bit in the SCC register equal to “1” and the
FSIDEN bit in the SCC register equal to “0”. When this instruction is executed under the conditions
described above, the following will occur:
•
The f
H
clock will be on but the f
SUB
clock will be off and the application program will stop at the
“HALT” instruction.
•
The Data Memory contents and registers will maintain their present condition.
•
The I/O ports will maintain their present conditions.
•
In the status register, the Power Down flag, PDF, will be set and the Watchdog time-out flag, TO,
will be cleared.
•
The WDT will be cleared and resume counting as the WDT function is always enabled.
Standby Current Considerations
As the main reason for entering the SLEEP or IDLE Mode is to keep the current consumption of the
device to as low a value as possible, perhaps only in the order of several micro-amps except in the
IDLE1 and IDLE2 Mode, there are other considerations which must also be taken into account by
the circuit designer if the power consumption is to be minimised. Special attention must be made to
the I/O pins on the device. All high-impedance input pins must be connected to either a fixed high or
low level as any floating input pins could create internal oscillations and result in increased current
consumption. This also applies to the device which has different package types, as there may be
unbonded pins. These pins must either be setup as outputs or if setup as inputs must have pull-high
resistors connected.
Care must also be taken with the loads, which are connected to I/O pins, which are setup as outputs.
These should be placed in a condition in which minimum current is drawn or connected only to
external circuits that do not draw current, such as other CMOS inputs. Also note that additional
standby current will also be required if the LIRC oscillator has enabled.