static void button_callback(const struct device *gpiob, struct gpio_callback *cb, uint32_t pins)
{
	int err;

	LOG_INF("Button pressed");
	if (ble_conn) {
		if (notify_enable) {
			err = bt_gatt_notify(NULL, &stsensor_svc.attrs[4], &but_val, sizeof(but_val));
			if (err) {
				LOG_ERR("Notify error: %d", err);
			} else {
				LOG_INF("Send notify ok");
				but_val = (but_val == 0) ? 0x100 : 0;
			}
		} else {
			LOG_INF("Notify not enabled");
		}
	} else {
		LOG_INF("BLE not connected");
	}
}