void ICACHE_RAM_ATTR CrowAlarmPanelStore::interrupt(CrowAlarmPanelStore *arg) {
  bool data_bit = arg->data_pin_->digital_read();

  // Check for boundary
  arg->boundary_buffer_ = (uint8_t)((arg->boundary_buffer_ << 1) | data_bit);

  uint8_t idx = arg->num_bits / 8;
  if (arg->inside_) {
    arg->buffer[idx] = (arg->buffer[idx] >> 1) | ((data_bit ? 1 : 0) << 7);
    arg->num_bits++;
    if (arg->boundary_buffer_ == BOUNDARY) {
      arg->message.type = arg->buffer[0];
      memcpy(arg->message.data_buffer, arg->buffer + 1, idx - 1);
      arg->message.data_len = idx - 1;
      arg->message_available = true;
      arg->inside_ = false;
      arg->num_bits = 0;
    }
    return;
  }

  if (arg->boundary_buffer_ == BOUNDARY) {
    arg->inside_ = true;
  }

  if (arg->inside_ && arg->num_bits > 200) {
    // Wrong side of boundary.
    arg->inside_ = false;
    arg->num_bits = 0;
  }
}