ST7LIT15BF0 STMicroelectronics, ST7LIT15BF0 Datasheet - Page 43

• Manufacturer Part Number: ST7LIT15BF0
• Description: 8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, DATA EEPROM, ADC, 5 TIMERS, SPI
• Manufacturer: STMicroelectronics

Specifications of ST7LIT15BF0

• Up To 4 Kbytes Single Voltage Extended Flash (xflash) Program Memory With Read-out Protection, In-circuit Programming And In-application Programming (icp And Iap). 10k Write/erase Cycles Guaranteed, Data Retention: 20 years at 55˚C.
• 128 Bytes Data Eeprom With Read-out Protection. 300k Write/erase Cycles Guaranteed, Data Retention: 20 years at 55˚C.
• Clock Sources: Internal 1% RC oscillator (on ST7FLITE15B and ST7FLITE19B), crystal/ceramic resonator or external clock
• Five Power Saving Modes: Halt, Active-Halt, Auto Wake-up from Halt, Wait and Slow

POWER SAVING MODES (Cont’d)
9.4.1 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, re-initialize the level sensi-
– The opcode for the HALT instruction is 0x8E. To
– As the HALT instruction clears the interrupt mask
wake up the microcontroller from Halt mode.
microcontroller, re-initialize the corresponding I/
O as “Input Pull-up with Interrupt” before execut-
ing the HALT instruction. The main reason for
this is that the I/O may be wrongly configured
due to external 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 pro-
gram memory 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).
9.5 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. The decision to enter either in ACTIVE-
HALT or HALT mode is given by the LTCSR/ATC-
SR register status as shown in the following table:
The MCU can exit ACTIVE-HALT mode on recep-
tion of a specific interrupt (see Table 5, “Interrupt
Mapping,” on page 37) or a RESET.
– When exiting ACTIVE-HALT mode by means of
– When exiting ACTIVE-HALT mode by means of
When entering ACTIVE-HALT mode, the I bit in
the CC register is cleared to enable interrupts.
Therefore, if an interrupt is pending, the MCU
wakes up immediately (see Note 3).
In ACTIVE-HALT mode, only the main oscillator
and the selected timer counter (LT/AT) are running
to keep a wake-up time base. All other peripherals
are not clocked except those which get their clock
supply from another clock generator (such as ex-
ternal or auxiliary oscillator).
Note: As soon as ACTIVE-HALT is enabled, exe-
cuting 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.
TB1IE bit
LTCSR1
a RESET, a 256 or 4096 CPU cycle delay oc-
curs. After the start up delay, the CPU resumes
operation by fetching the reset vector which
woke it up (see
an interrupt, the CPU immediately resumes oper-
ation by servicing the interrupt vector which woke
it up (see
0
0
1
x
ATCSR
OVFIE
Figure
bit
x
0
x
1
Figure
ATCSR
CK1 bit
28).
x
x
x
0
28).
ATCSR
CK0 bit
0
x
x
1
ST7LITE1xB
ACTIVE-HALT
mode disabled
ACTIVE-HALT
mode enabled
Meaning
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