PFS154 datasheet(38/91 Pages) PADAUK

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PFS154

8bit MTP Type IO Controller

Page 38 of 91

PDK-DS-PFS154_CN_V105 –Jun. 9, 2020

5.8. Power-Save and Power-Down

There are three operational modes defined by hardware: ON mode, Power-Save mode and Power-Down

modes. ON mode is the state of normal operation with all functions ON, Power-Save mode (“stopexe”) is the

state to reduce operating current and CPU keeps ready to continue, Power-Down mode (“stopsys”) is used to

save power deeply. Therefore, Power-Save mode is used in the system which needs low operating power with

wake-up occasionally and Power-Down mode is used in the system which needs power down deeply with

seldom wake-up. Table 5 shows the differences in oscillator modules between Power-Save mode (“stopexe”)

and Power-Down mode (“stopsys”).

Differences in oscillator modules between STOPSYS and STOPEXE

IHRC

ILRC

STOPSYS

Stop

STOPEXE

No Change

Table 5: Differences in oscillator modules between STOPSYS and STOPEXE

5.8.1 Power-Save mode (“stopexe”)

Using “stopexe” instruction to enter the Power-Save mode, only system clock is disabled, remaining all the

oscillator modules be active. For CPU, it stops executing; however, for Timer16, counter keep counting if its

clock source is not the system clock. The wake-up sources for “stopexe” can be IO-toggle or Timer16 counts to

set values when the clock source of Timer16 is IHRC or ILRC modules,or wakeup by comparator when setting

GPCC.7=1 and GPCS.6=1 to enable the comparator wakeup function at the same time. Wake-up from input

pins can be considered as a continuation of normal execution, the detail information for Power-Save mode

shown below:

(1) IHRC oscillator modules: No change, keep active if it was enabled

(2) ILRC oscillator modules: must remain enabled, need to start with ILRC when be wakening up

(3) System clock: Disable, therefore, CPU stops execution

(4) MTP memory is turned off

(5) Timer counter: Stop counting if its clock source is system clock or the corresponding oscillator module is

disabled; otherwise, it keeps counting. (The Timer contains TM16, TM2, TM3, PWMG0, PWMG1,

PWMG2.)

(6) Wake-up sources:

a. IO toggle wake-up: IO toggling in digital input mode (PxC bit is 1 and PxDIER bit is 1)

b. Timer wake-up: If the clock source of Timer is not the SYSCLK, the system will be awakened when

the Timer counter reaches the set value.

c. Comparator wake-up: It need setting GPCC.7=1 and GPCS.6=1 to enable the comparator wake-up

function at the same time.

An example shows how to use Timer16 to wake-up from “stopexe”:

$ T16M

ILRC, /1, BIT8

// Timer16 setting

…

WORD

count

STT16

count;

stopexe;

…

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