avoid initial signal at initial serial connection

[kisk-ski]

Hello,

Now I am trying to use Arduino just as USB-UART converter.
I just write following code without bootloader and disconnect RXD and TXD of atmaga328P-PU from Arduino Pin0 and Pin1.
(atmega32 also generate CLK on pin10 for external device)

But when I initially open com port of Arduino from PC, initial signal is appeared on Pin0 of Arduino and pin10 CLK is also stopped.
(see attached No1)
Data is correctly sent after this initial signal.
(see attached No2)

When I secondry open this com port, this signal is not appeared before data.
(see attached No3)

I tried to press RST switch but initial signal is not appeared ever.
It might only appeared at first connection of PC and Arduino.

Is there any way to avoid thiese initial signal ?

• code -

#include <avr/io.h>
#define PWMPin 10

void setup() {
pinMode(PWMPin, OUTPUT);
/*

• See P107~113
• WGM 1001 Phase and Frequency Correct
• CS 001 No prescaling
• SysCLK 16MHz
  /
  TCCR1A= (1<<5)|(1<<0);
  TCCR1B =(1<<4)|(1<<0);
  OCR1A = (unsigned int)(52); //(16MHz/2) / (960016)
  OCR1B = (unsigned int)(52/2);
  }

void loop() {
}

• code -

[ieee488]

https://forum.arduino.cc/index.php?topic=363128.0

[kisk-ski]

Thank you for your kind reply.
I tried to remove C5 (between DTR of ATMEGA16 and RST of ATMEGA32) but still have problem.
CLK stop phenomena is improved but initial signal on Pin0 (TX of ATMEGA16) is still exist.
(See attached waveform)

As I described, I disconnected ATMEGA32 and Arduino Pin0 and Pin1, so I guess ATMEGA32 cannot effect Pin0 signal (TX of ATMEGA16).

I think I need to avoid reset working of ATMEGA16 on initial serial connection.
Is there any good way ?