It’s a prop bomb countdown timer built on a D1 Mini (ESP8266).
Hardware: D1 Mini, SPI OLED display, passive buzzer, 2 LEDs, and a relay module powered from an external 5V supply.
What it does: Counts down from 5 to 0 on the OLED with increasing …
It’s a prop bomb countdown timer built on a D1 Mini (ESP8266).
Hardware: D1 Mini, SPI OLED display, passive buzzer, 2 LEDs, and a relay module powered from an external 5V supply.
What it does: Counts down from 5 to 0 on the OLED with increasing beep pitch and blinking LEDs each tick. At 0 it triggers a relay, then runs a “boom” sequence — rapid LED strobing, a siren wail from the buzzer, and a “* BOOM * (not really)” screen.
The journey to get it working:
∙ Started with I²C OLED, swapped to SPI
∙ Fixed the display.begin() call (wrong init constant for SPI mode)
∙ Debugged the relay through several layers — wiring, voltage, current, timing — eventually isolating it to a code timing issue where the relay fired too late due to blocking tone_play loops and a duplicate digitalWrite in two places
