ST7LITE20F2 datasheet(53/166 Pages) STMICROELECTRONICS

Part #	ST7LITE20F2

Description	8-bit microcontroller with single voltage Flash memory, data EEPROM, ADC, Timers, SPI

PDF	166 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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53 / 166 page

ST7LITE20F2 ST7LITE25F2 ST7LITE29F2

Power saving modes

Doc ID 8349 Rev 5

53/166

SLOW mode is controlled by the SMS bit in the MCCSR register which enables or disables

SLOW mode.

In this mode, the oscillator frequency is divided by 32. The CPU and peripherals are clocked

at this lower frequency.

Note:

SLOW-WAIT mode is activated when entering WAIT mode while the device is already in

SLOW mode.

Figure 22. SLOW mode clock transition

9.3

WAIT mode

WAIT mode places the MCU in a low power consumption mode by stopping the CPU.

This power saving mode is selected by calling the “WFI” instruction.

All peripherals remain active. During WAIT mode, the I bit of the CC register is cleared, to

enable all interrupts. All other registers and memory remain unchanged. The MCU remains

in WAIT mode until an interrupt or RESET occurs, whereupon the Program Counter

branches to the starting address of the interrupt or Reset service routine.

The MCU will remain in WAIT mode until a RESET or an Interrupt occurs, causing it to wake

up.

Refer to Figure 23.

SMS

fCPU

Normal Run mode

request

fOSC

fOSC/32

fOSC

ST7LITE20F2 Datasheet(PDF) 53 Page - STMicroelectronics