ST72344S4 STMicroelectronics, ST72344S4 Datasheet - Page 70

• Manufacturer Part Number: ST72344S4
• Description: 8-bit MCU
• Manufacturer: STMicroelectronics

Specifications of ST72344S4

• Up To 16 Kbytes Program Memory: single voltage extended Flash (XFlash) with readout and write protection, in-circuit and inapplication programming (ICP and IAP). 10K write/erase cycles guaranteed, data retention
• 256 Bytes Data Eeprom With Readout Protection. 300k Write/erase Cycles Guaranteed, Data Retention: 20 years at 55 °C.
• Clock Sources: crystal/ceramic resonator oscillators, high-accuracy internal RC oscillator or external clock
• 5 Power-saving Modes: Slow, Wait, Halt, Auto-wakeup from Halt and Active-halt
• 16-bit Timer A With: 1 input capture, 1 output compares, external clock input, PWM and pulse generator modes
• 16-bit Timer B With: 2 input captures, 2 output compares, PWM and pulse generator modes

Power-saving modes
9.6
70/247
Auto-wakeup from Halt mode
Auto-wakeup from Halt (AWUFH) mode is similar to Halt mode with the addition of an
internal RC oscillator for wake-up. Compared to Active-Halt mode, AWUFH has lower power
consumption because the main clock is not kept running, but there is no accurate real-time
clock available.
It is entered by executing the HALT instruction when the AWUEN bit in the AWUCSR
register has been set and the OIE bit in the MCCSR register is cleared (see
page 88
Figure 32. AWUFH mode block diagram
As soon as Halt mode is entered, and if the AWUEN bit has been set in the AWUCSR
register, the AWU RC oscillator provides a clock signal (f
a fixed divider and a programmable prescaler controlled by the AWUPR register. The output
of this prescaler provides the delay time. When the delay has elapsed the AWUF flag is set
by hardware and an interrupt wakes-up the MCU from Halt mode. At the same time the main
oscillator is immediately turned on and a 256 or 4096 cycle delay is used to stabilize it. After
this startup delay, the CPU resumes operation by servicing the AWUFH interrupt. The AWU
flag and its associated interrupt are cleared by software reading the AWUCSR register.
To compensate for any frequency dispersion of the AWU RC oscillator, it can be calibrated
by measuring the clock frequency f
Measurement mode is enabled by setting the AWUM bit in the AWUCSR register in Run
mode. This connects internally f
f
Similarities with Halt mode
The following AWUFH mode behavior is the same as normal Halt mode:
●
●
●
●
AWU_RC
The MCU can exit AWUFH mode by means of any interrupt with exit from Halt
capability or a reset (see
When entering AWUFH mode, the I[1:0] bits in the CC register are forced to 10b to
enable interrupts. Therefore, if an interrupt is pending, the MCU wakes up immediately.
In AWUFH mode, the main oscillator is turned off causing all internal processing to be
stopped, including the operation of the on-chip peripherals. None of the peripherals are
clocked except those which get their clock supply from another clock generator (such
as an external or auxiliary oscillator like the AWU oscillator).
The compatibility of Watchdog operation with AWUFH mode is configured by the
WDGHALT option bit in the option byte. Depending on this setting, the HALT instruction
when executed while the Watchdog system is enabled, can generate a Watchdog
reset.
for more details).
to be measured using the main oscillator clock as a reference timebase.
f
AWU_RC
AWU RC
oscillator
divider
Section 9.4: Halt mode on page
Doc ID 12321 Rev 5
/64
AWU_RC
AWU_RC
to the ICAP2 input of the 16-bit timer A, allowing the
and then calculating the right prescaler value.
to Timer input capture
prescaler
AWUFH
/1 .. 255
AWU_RC
AWUFH
interrupt
66).
). Its frequency is divided by
ST72344xx ST72345xx
Section 11.2 on