ok to use RTS instead of DTR on FTDI to Pro Mini???

I just started having issues with my FTDI breakout board that I've been using to program some 'minimOSD' PCB's, which are basically Pro Mini's (328p 5V 16MHz). For some reason, the FTDI USB adapter is no longer able to reset the Atmega; I can't upload sketches without using the 'reset button' trick, and opening/changing the baud in serial monitor also doesn't reset the board. I tried burning the bootloader multiple times with my USBASP and it made no difference.

Anyway, I discovered somewhere here on the forums that avrdude supports using both the RTS and DTR pins in order to send the reset commands. I tested it out by changing the connection from the minimOSD to the FTDI breakout so that it uses the RTS pin instead of the DTR pin. Without changing anything else in software or hardware, it worked, and I was able to successfully upload sketches from the Arduino IDE without having to manually reset the minimOSD.

So, my question is "is this ok?" Is it alright to use the RTS pin instead of the DTR pin? Are there any technical differences that can cause problems or possibly damage either the AVR or the FTDI chip? What's the main difference between using one pin or the other? Also, does anyone have any ideas as to why the DTR pin might no longer be functioning to reset the ATMega???

I'd appreciate any help/feedback, thanks...

So, my question is "is this ok?" Is it alright to use the RTS pin instead of the DTR pin? Are there any technical differences that can cause problems or possibly damage either the AVR or the FTDI chip? What's the main difference between using one pin or the other? Also, does anyone have any ideas as to why the DTR pin might no longer be functioning to reset the ATMega???

On the first board that arduino developed that used an auto-reset feature the IDE used the RTS control signal to trigger the reset to the board. On later boards they changed to using the DTR signal to use that (I recall no reason given for the change) for the trigger signal. So to keep compatibility they had to issue both RTS and DTR pulses. There should be no issue in the future but who knows what the future may bring. One issue is that when opening the serial monitor the DTR is pulsed which causes a board reset and I don't recall if opening the serial monitor pulses RTS or not, probably not and it would be easy for you to test this.

Hi, yes it is totally fine to use RTS instead of DTR. And to answer the question of whether it will pulse your arduino and autoreset it when you plug it in, the answer is yes. At least this definitely works with my FTDI board and my breadboard arduino.