Problem of COM port opening

Official Hardware Nano Family Nano Every
1

I wrote an C# application to communicate with an Arduino Nano Every. When I plug the USB connector to Arduino for the 1st time, the port opened but doesn't communicate (the Arduino must send a message with Serial.println("Hello!"); that I don't receive). Even if I press the PB reset on the board, nothing happens.
Remark: the Arduino is supplied only via USB plug.
If I launch the Serial Monitor from Arduino IDE I receive the write message (Hello!). Now, if I return to my C# program and run it again, I receive the right message "Hello!" on each reset, until I'll disconnect the USB.

I tried an experiment:
I load this simple program in my Arduino:

void setup() {
Serial.begin(9600);
Serial.println("Hello!");
pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
Serial.println("HIGH");
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
Serial.println("LOW");
delay(1000); // wait for a second
}

and I launch a serial terminal software (Termite 3.4).
I can observe the same behavior that is after plugging USB the terminal output displays a sequence of [00][00]....just after reset and so after each second.
Now, if I launch the Arduino IDE Serial Monitor, I receive immediately the right message:
Hello!
HIGH
LOW
...
And if I launch the Termite Terminal instead of Serial Monitor, I receive the same right message.

Thank you to enlighten me.

2

Does Termite hold down DTR when it opens communication? It's needed to reset the Arduino.

3

maybe not, I don't know.
But I can do it in my C# application. What must I to do?

4

is it done by software?

5

Hold down DTR when serial communication is started. You can keep it low or just give a short pulse of let's say 100ms at the start of the session, it shouldn't matter much. Yes, it's done in software.

6

I don't understand.
I use the USB connector of Arduino Nano Every. It has its own USB-UART transceiver. I looked at the board schematic, there is no DTR signal.
If it is done in software, what is the instruction code?

7

Sorry, I missed that you use an Every. Maybe this will help: Reset Nano Every - Toggling RTS and DTR doesn't do it
Open com at 1200baud, close it, and then open again at desired baud rate.

8

Opening the port at 1200 baud and closing it should do the reset.

Where doing this? In the Arduino code or in my C# application?

9

There.

10

I just tried, it doesn't work.

11

Sounds like your C# program isn't doing what it's supposed to do then. It's outside the scope of Arduino itself and I have no experience with C# specifically, so I can't help you with that. Perhaps try in this category: Interfacing w/ Software on the Computer - Arduino Forum

12

Well, I finally found the solution.

In my C# application:

SerialPort PulseComPort;
...
PulseComPort.Open();
PulseComPort.DtrEnable = true;
Thread.Sleep(150);

After opening the port, I must enable Dtr and (very important) wait a delay before send message.
It is working.
I deduced that the Serial Monitor do this and not the Termite terminal.
Thank you

13

Nice! Great to see you've got it working, good job!