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Cortex-M33 wake up from SLEEPDEEP

Yael Kanter-Weisman

Hi, 

Does the Cortex-M33 can wake up from SLEEPDEEP by NVIC only or that the WIC is a must in this case?

according to the iim -

11.6.1 Standard sleep

In this mode, the WIC is inactive and it is the NVIC that is responsible for monitoring incoming interrupts and waking up the processor. The internal clock signals are gated to save power.

11.6.2 Deep sleep

The processor regards deep sleep mode to be identical to standard sleep mode. This mode allows deeper levels of sleep that are entirely system defined. For example, deep sleep can be used to shut down a system PLL, and for switching to a low frequency clock, to achieve greater power savings at the expense of wake-up latency.

But I want to make sure that identical allows wake up by NVIC.

Regards

Yael

  • 0 Arm Employee Badge

    When the processor is sleeping, most of its internal clock gates are switched off, to save dynamic power in the processor. A small part of the processor, that is mainly the interrupt and event interface of the NVIC component, needs to remain clocked so that it can detect interrupts and other events that might cause the processor to wake up.
     
    For normal sleep, the processor asserts its SLEEPING output, and the power saving is limited to gating some internal clocks, so that wake-up is immediate.
     
    Deep sleep occurs if the processor goes to sleep while software has programmed the SLEEPDEEP bit in the System Control Register to ‘1’. Again, the processor asserts its SLEEPING output, but also asserts its SLEEPDEEP output, which is the logical AND of SLEEPING and SCR.SLEEPDEEP. In this mode, the system has the option to perform additional power saving in the processor, that might cause the processor to take longer to respond to a wakeup event, but even in deep sleep, the NVIC still has the responsibility of detecting wakeup events so that the processor can be woken up.
     
    Cortex-M processors generally implement a further qualification of deep sleep, called WIC-based sleep. This makes use of an optional component called a Wake-up Interrupt Controller, or WIC, to take over responsibility for detecting wake-up events, meaning that the power-saving modes in the system can include making the NVIC fully quiescent.