Wemos D1 Mini Pro Digital Interrupt Pins

I was observing weird behavior when trying to handle interrupts from certain pins on a WEMOS D1 mini Pro.

Goal

• Register ISRs for rising and falling edges on as many pins as possible
• Keep a stable system
• Keep I²C functionality

TL;DR

• The pins D5, D6, D7 work without restrictions
• D3 and D4 work, but can not be low on boot, otherwise the WEMOS freezes¹²
• D1 and D2 are used for I²C by default³, not changed for compability
• D0⁴ and D8⁵ have no support for interrupts

Implementation

ICACHE_RAM_ATTR void my_isr(){ /* ... */ }

void setup() {
  pinMode(MY_INT_PIN, INPUT_PULLUP);
  attachInterrupt(MY_INT_PIN, my_isr, CHANGE);
}