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rocketscream / Low-Power

Low Power Library for Arduino
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Setting SAMD21 to Sleep (idle) is not doing anything #78

Closed Jackjan4 closed 5 years ago

Jackjan4 commented 5 years ago

Hi,

when I use the library for an SAMD21 (Adafruit Feather M0) to put the SAMD21 in one of its idle modes (Idle 0 to idle 2) its not going into idle mode. It just executes the code after the idle code directly instead of listening on external interrupt. However, if I use standby (LowPower.standby()) it is working fine.

Jackjan4 commented 5 years ago

Further investigation showed that this was obviously due to the fact that interrupts are still called from other places within the system. So this is not a problem of LowPower.

jsiddall commented 3 years ago

In case anyone comes across this searching, as I did, it is possible to turn off systick which prevents idle from returning every millisecond:

SysTick->CTRL &= ~SysTick_CTRL_TICKINT_Msk;
LowPower.idle(IDLE_2);
SysTick->CTRL |= SysTick_CTRL_TICKINT_Msk;