Power Management for Microcontrollers

Making a battery last.

Current draw rises with clock speed and with every active peripheral. Lowering the clock, turning off unused modules and sleeping between tasks can cut average current by a large factor.

Estimate battery life as capacity divided by average current. A node that draws 10 mA for 1 second then sleeps at a tiny current for 59 seconds averages far below 10 mA.

Also watch the supply: add a bypass capacitor close to each chip's power pins and keep the voltage inside the chip's allowed range.