Battery-powered IoT sensors are expected to operate for five to ten years without maintenance. While battery chemistry dictates capacity, firmware efficiency is the deciding factor in device longevity.
A typical microcontroller consumes milliamperes of current during execution, but microamperes during deep sleep. Maximizing battery life means keeping the core in sleep mode as close to 100% of the time as possible.
"Squeezing years of runtime out of small cells requires treating every clock cycle as a precious power resource."
Implementing Sleep States
Microcontrollers offer multiple low-power states, shutting down peripherals, clocks, and memory registers. Firmware must be structured around interrupt-driven wakeups, waking the CPU only when a sensor threshold is crossed or a timer expires.
Clock Gating and Peripherals
Leaving unused peripherals active is a major source of power leakage. Disabling clock distribution to inactive registers (clock gating) and using external load switches to power off sub-circuits guarantees that zero current is wasted during sleep cycles.