ESP32-C3 supermini

 I used one of these recently for a single one-shot timer. For a simple timer with one I/O pin the min is even overkill because it has about 8 I/O pins most of them usable for anything and wifi. 

I did not use the wifi for my timer and did not disable it, so maybe I should do that now.

Here is a list of pins to not connect to peripherals that might pull them into states the prevent booting

Pin	Affect on the boot up
GPIO2	If low, normal flash boot may fail
GPIO8	If low, flashing/boot may not fail
GPIO9	If low normal flash boot may fail

From below

From above

Simple one-shot timer sketch

void setup() {

  // put your setup code here, to run once:

  // after power up wait a while, turn on output, wait then turn output off and go to sleep

  pinMode(8, INPUT);

  delay(8000);

}

int once = 1;

void loop() {

  // put your main code here, to run repeatedly:

  if (once) {

  delay(1000);

  pinMode(8, OUTPUT);

  digitalWrite(8, LOW);

  delay(300);

  digitalWrite(8, HIGH);

  pinMode(8, INPUT);

  once = 0;

  }

}

Possibly the most overkill one-shot way to use the 3.3V of the micro to drive a 3V coin-cell load.

Simple project that briefly presses the remote on an action cam. 1. wait a determined interval to allow the action cam to boot 2. press the button for abotu 100ms to start recording This works because the ESP32-supermini is powering the camera as passthrough using the 5V pin to just supply USB power. So we get power at the same time and know roughly how long the camera takes to scan the SD card.

Works with 256 and 512GB Sandisk or Kingston class 1 .