Data sent to Serial2 shows up in Serial Monitor

[Max]

Hi Forum members,

i worked a bit with arduino and controllino for some basic projects. But now I have to setup a serial connection between a Nextion Display and a Controllino Mega.

I am encountering a strange behaviour.
My Controllino is connected to my PC by USB.
The Nextion Display is connected to the Controllino by Pin 16 / 17 of X2.
As my Controllino runs with 24V I am supplying the Nextion Display with a 5V power source.

Now, when I execute the following code, everything I print to Serial2 is sent to the Serial Monitor instead to the Nextion Display. Weird.

I spent days of searching, reading and trying. But I assume I need some professional help ;-).

uint32_t interval = 1000; //milliseconds
uint32_t nextMillis;
uint8_t in_byte=0x00;
uint8_t ndt[3]={255,255,255};
void setup() {
Serial.begin(115200);
Serial2.begin(115200);
Serial.println("Serial started");
Serial.println(" ");
nextMillis = millis();
}
void loop() {
if(millis()-nextMillis >= interval) {
Serial.print(millis());
execute();
nextMillis += interval;
}
}
void execute() {
Serial.print(" Bytes: ");
Serial.print(Serial2.available());
Serial.print(" Data: ");
while (Serial2.available()) {
in_byte = Serial2.read();
Serial.print(char(in_byte));
Serial.print(" ");
}
Serial.println();
Serial2.print("t0.txt=\"");
Serial2.print(nextMillis);
Serial2.print("\"");
Serial2.write(ndt,3);
}

[Lukas]

Hi Max,

have you tried to supply the display from the 5V at the CONTROLLINO pinheader? If you are using external 5V adapter – have you interconnected GND of CONTROLLINO and GND of the display?

From your description it seems that RX and TX are interconnected at the display side …

Any progress so far?

Thanks,

Lukas

[Max]

Hi Lukas,

thank you for your reply. It pointed me to the problem.
As the Nextion Display requires more power than the pinheader supplies I connected it to an external 5V power supply.

Now, I connected the 5V GND’s of the external power supply and the Controllino pinheader.
Now i am getting a clean signal.

Thank you for directing me towards the solution!

Best Regards,

Max