リセット後もカウンターを保持する

Let's build a press counter that remembers its total even after a power cut. We'll combine debouncing with EEPROM storage.

On startup, load the saved count. On each clean press, add one and save it back. Simple, but powerful.

Reserve one EEPROM address for the counter. We'll keep it small enough to fit in a single byte for now.

Inside setup(), read the saved value first. Now your counter picks up exactly where it left off.

A fresh chip's EEPROM often reads 255. Treat that as empty and reset your counter to zero on the first run.

Detect presses with the millis() debounce from before. Clean input is essential, or your saved count drifts upward.

When a debounced press fires, bump the counter by one. This is the single moment your total grows.

Use EEPROM.update to write the new total. It only touches memory when the value actually changed, protecting the chip.

Press a few times, then unplug and replug the board. The Serial Monitor shows your count continuing, not restarting. 🎉

A byte counter wraps back to 0 after 255. For bigger totals, store an int with EEPROM.put and EEPROM.get instead.

A real product often needs a way to clear the saved count. A long button hold could write 0 back to EEPROM.

Let's check the key step that lets the counter survive a reset.

You built a counter that persists by loading from EEPROM at boot and saving each clean press. Your device finally has a memory! 🧠