diff --git a/firmware/test1/heizung-test1/src/main.cpp b/firmware/test1/heizung-test1/src/main.cpp
index f4ccf302bff9c638d731db0d85c68b13aaa3022e..39b274332abfe9c5921674c815623204b968ae17 100644
--- a/firmware/test1/heizung-test1/src/main.cpp
+++ b/firmware/test1/heizung-test1/src/main.cpp
@@ -75,12 +75,16 @@ void setup() {
   pinMode(MATRIX_IN1, INPUT_PULLUP);
   pinMode(MATRIX_IN3, INPUT_PULLUP);
 
+  pinMode(TX_EN, OUTPUT);
+  digitalWrite(TX_EN, LOW);
+
   Serial1.setTX(TX);  // UART0
   Serial1.setRX(RX);
   Wire.setSDA(I2C_OLED_SDA);  // I2C0
   Wire.setSCL(I2C_OLED_SCL);
 
   Serial.begin(9600);  // USB serial, baudrate is ignored
+  Serial1.begin(115200);
   Wire.begin();
   Wire.setClock(100000);
 
@@ -490,5 +494,26 @@ void loop() {
     pixelsDisplay.show();
   }
 
+  static int rs485_timer = 0;
+  static int rs485_state = 0;
+  if ((rs485_timer < 10 || !pixelsDisplay.canShow()) && 0) {
+    rs485_timer++;
+  } else {
+    rs485_timer = 0;
+    rs485_state += 1;
+
+    if (0) {
+      digitalWrite(TX_EN, HIGH);
+      Serial1.print("Test ");
+      Serial1.println(rs485_state);
+    } else {
+      digitalWrite(TX_EN, LOW);
+    }
+  }
+  if (Serial1.available()) {
+    Serial.print("RX: ");
+    Serial.println(Serial1.read());
+  }
+
   delay(1);
 }
\ No newline at end of file