ST72361K6 STMicroelectronics, ST72361K6 Datasheet - Page 40

• Manufacturer Part Number: ST72361K6
• Description: 8-bit MCU
• Manufacturer: STMicroelectronics

Specifications of ST72361K6

• Hdflash Endurance: 100 cycles, data retention 40 years at 85°C
• 5 Power Saving Modes: Halt, Auto Wake Up From Halt, Active Halt, Wait and Slow

ST72361
POWER SAVING MODES (Cont’d)
Halt Mode Recommendations
– Make sure that an external event is available to
– When using an external interrupt to wake up the
– For the same reason, reinitialize the level sensi-
– The opcode for the HALT instruction is 0x8E. To
– As the HALT instruction clears the interrupt mask
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wake up the microcontroller from Halt mode.
microcontroller, reinitialize the corresponding I/O
as “Input Pull-up with Interrupt” before executing
the HALT instruction. The main reason for this is
that the I/O may be wrongly configured due to ex-
ternal interference or by an unforeseen logical
condition.
tiveness of each external interrupt as a precau-
tionary measure.
avoid an unexpected HALT instruction due to a
program counter failure, it is advised to clear all
occurrences of the data value 0x8E from memo-
ry. For example, avoid defining a constant in
ROM with the value 0x8E.
in the CC register to allow interrupts, the user
may choose to clear all pending interrupt bits be-
fore executing the HALT instruction. This avoids
entering other peripheral interrupt routines after
executing the external interrupt routine corre-
sponding to the wake-up event (reset or external
interrupt).
8.5 ACTIVE HALT MODE
ACTIVE HALT mode is the lowest power con-
sumption mode of the MCU with a real time clock
available. It is entered by executing the ‘HALT’ in-
struction when MCC/RTC interrupt enable flag
(OIE bit in MCCSR register) is set and when the
AWUEN bit in the AWUCSR register is cleared
(See “Register Description” on page
The MCU can exit ACTIVE HALT mode on recep-
tion of the RTC interrupt and some specific inter-
rupts (see
33) or a RESET. When exiting ACTIVE HALT
mode by means of a RESET a 4096 or 256 CPU
cycle delay occurs (depending on the option byte).
After the start up delay, the CPU resumes opera-
tion by servicing the interrupt or by fetching the re-
set vector which woke it up (see
When entering ACTIVE HALT mode, the I[1:0] bits
in the CC register are are forced to ‘10b’ to enable
interrupts. Therefore, if an interrupt is pending, the
MCU wakes up immediately.
In ACTIVE HALT mode, only the main oscillator
and its associated counter (MCC/RTC) are run-
ning to keep a wake-up time base. All other periph-
erals are not clocked except those which get their
clock supply from another clock generator (such
as external or auxiliary oscillator).
The safeguard against staying locked in ACTIVE
HALT mode is provided by the oscillator interrupt.
Note: As soon as active halt is enabled, executing
a HALT instruction while the Watchdog is active
does not generate a RESET.
This means that the device cannot spend more
than a defined delay in this power saving mode.
MCCSR
OIE bit
0
1
HALT mode
ACTIVE HALT mode
Power Saving Mode entered when HALT
Table 9, “Interrupt Mapping,” on page
instruction is executed
Figure
44.)
28).