About closing arduino serial monitor screen

I just came across this yesterday that someone I'm corresponding with has got into trouble by closing the arduino serial monitor screen. According to him, his outputs became "HIGH" every time he closes the serial monitor. I wonder whether there is any consequences with closing the serial monitor. I know if you open it, arduino IDE resets arduino board by toggling the reset pin. What about closing? Does arduino IDE do anything specific that will affect the arduino board, such as with the reset pin? I just want to see if it's related with IDE or software he wrote. Thanks.

Closing the monitor also toggles the reset pin.

Thanks Mike! That makes little sense. If you just want to see some debug output and then close it, the whole code restarts. I'll recommend the guy to use termite or other terminal programs that don't specifically do this. Of course you can set it to do DTR or just click a DTR button in the program.

That makes little sense.

It is not as if it were planned like this, it is just a consequence of using a signal that changes on opening and closing the serial port to do a reset. If you want to change this behavior then you would have to use the DTR signal to feed an edge triggered monostable. The it would reset on connection but not removal. However, it adds to the cost of the board.

If either of you two (or others) might want to try an interesting experiment with the auto-reset function, I can share what I found to be true while I was working with others on that auto-reset 'latch-up' problem last year. As you might know I was trying to participate with the validation of the problem, but not owning a Uno board I was using the older standard 2009 board. I was using a PC serial monitor program (brey terminal) to activate the DTR signal on and off as that program has a button to manipulate DTR signal. Here was my findings before and after the diode pull-up fix was proposed as a fix for the latch-up problem.

Before installing the pull-up diode between reset pin and +5vdc:

Turning the DTR signal from off to on would generate a reset on the attached arduino. Turning the DTR signal from on to off would also generate a reset on the arduino.

After installing the pull-up diode between reset and +5vdc:

Turning the DTR signal from off to on would generate a reset on the attached arduino. Turning the DTR signal from on to off would NOT generate a reset on the attached arduino.

liudr: I propose that that if your friend was to install the diode on his arduino board he may very find out that shutting the serial terminal down will then not reset his board, only opening the monitor will. He might also see a different behaviour is tries using the Uno Rev 3 board that also has the diode installed as standard issue now.

Take it for what it's worth;

Lefty

Lefty,

Thanks for the info. I have an UNO R2 board. I'll give it a try at home. I use termite terminal. It has a similar button for various control lines such as DTR.

Before installing the pull-up diode between reset pin and +5vdc:

Turning the DTR signal from off to on would generate a reset on the attached arduino. Turning the DTR signal from on to off would also generate a reset on the arduino.

I got the same thing on UNO R2.

Now how do you install a diode between reset and 5V?

Just solder it on the under side of the board.

Grumpy_Mike:
Just solder it on the under side of the board.

Like this?

5V—|<|—Reset

:cold_sweat: :cold_sweat: :cold_sweat:

liudr:

Grumpy_Mike:
Just solder it on the under side of the board.

Like this?

5V—|<|—Reset

:cold_sweat: :cold_sweat: :cold_sweat:

I think so (ascii art sucks) Cathode to +5vdc, anode to reset pin.
5v…|<…reset

Lefty

Alright thanks again!