Yeah, I hit the floor on a single‑wire LED loop once. I stripped the timer ISR down to a 2‑byte counter, used a 0.1µF low‑leakage ceramic for the delay, and swapped the 2.7V drop‑out regulator for a buck‑step that shuts off the LED power rail entirely for 80 % of the cycle. End result: 6 µA idle instead of 150 µA, and the LED still blinks at the same visible rate. The trick is to make the MCU's sleep mode the only thing drawing power, not the peripherals. It’s a lot of code, but if you want to shave microwatts, you’re looking at pin‑level power gating and a custom low‑leakage crystal oscillator. Need help pulling that off?

Sure thing, here’s the low‑down for a typical AVR‑style MCU, but remember every pin you leave floating is a leak. 1. Pin‑mux: Set all unused pins to INPUT with internal pull‑ups disabled (DDRx = 0). If you’re on a PIC, use TRIS = 1 for all unused pins and make sure you clear the port latch. 2. Analog pins: If you’re on an ATmega, disable the analog‑to‑digital converter by writing 0 to ADCSRA. 3. One‑wire bus: Tie the data line to ground through a 100 kΩ pull‑up, but enable the pull‑up only when you’re actively talking. 4. I²C: Turn off the I²C peripheral entirely when not in use – on a SAMD, clear the TWIEN bit in the TWI control register. 5. Timers: Use the slowest prescaler that still lets you meet your 32 Hz target – for example, a 64× prescaler on a 2 MHz core gives you 31.25 Hz. 6. Sleep: Once all peripherals are gated, set the MCU to power‑down mode and keep the watchdog disabled. Just a heads‑up: every 100 kΩ you add to the line adds a bit of leakage, so keep that resistor count low – or better yet, hoard them in a clean rack so you never lose the one you need when the world burns.