Sleep modes and clock gating reduce energy for battery devices.
Techniques: sleep, stop and standby modes, clock scaling, peripheral gating, duty cycling, interrupt-driven design, low-power sensors and efficient regulators. Average current governs battery life: t=capacity/I_avg. Measure with a current profiler.
A sensor node sleeping 99.9% of the time can run for years on a coin cell.
Power modes extend battery life, because a sleeping processor and gated clocks draw only microamps.
Sleep modes and clock gating reduce energy for battery devices.
Power modes extend battery life, because a sleeping processor and gated clocks draw only microamps.
Turning off the clock to unused logic, which stops its switching and reduces dynamic power without losing state in the registers.
Typically an interrupt from a timer, a pin change or a communication event, which must be configured before sleeping.
Typical applications include putting a sensor node to sleep between measurements to run for years on a coin cell, stopping unused peripheral clocks to save current and choosing the lowest power mode that still wakes on a timer or pin change.
Study "Bootloaders and startup code" first (topic 73 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
Sleep current µA vs run mA. Wake-up sources. Leakage in pull-ups.
A sensor node sleeping 99.9% of the time can run for years on a coin cell.
The next topic is "Watchdog timers", which builds directly on this one.
It is classed as Advanced in Electronics & Embedded (topic 74 of 104). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Electronics & Embedded.
Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.