Fixing buggy millis use

ampel-firmware/led_effects.cpp

@@ -146,8 +146,7 @@ namespace led_effects {
     static uint16_t wheel_offset = 0;
     unsigned long t0 = millis();
     pixels.setBrightness(config::max_brightness);
-    //FIXME: OVERFLOW!
-    while (millis() < t0 + duration_ms) {
+    while (millis() - t0 < duration_ms) {
       for (int i = 0; i < NUMPIXELS; i++) {
         pixels.setPixelColor(i, pixels.ColorHSV(i * 65535 / NUMPIXELS + wheel_offset));
         wheel_offset += hue_increment;

ampel-firmware/lorawan.cpp

@@ -184,8 +184,7 @@ namespace lorawan {
   void preparePayloadIfTimeHasCome(const int16_t &co2, const float &temperature, const float &humidity) {
     static unsigned long last_sent_at = 0;
     unsigned long now = seconds();
-    //FIXME: OVERFLOW!
-    if (connected && (now > last_sent_at + config::lorawan_sending_interval)) {
+    if (connected && (now - last_sent_at > config::lorawan_sending_interval)) {
       last_sent_at = now;
       preparePayload(co2, temperature, humidity);
     }