Given a serial to usb connection over an ftdi chip (like sparkfun's FTDI Basic Breakout - 3.3V - DEV-08772 - SparkFun Electronics) how does one manipulate the DTR pin from the computer side to cause a reset (supposedly the DTR pin causes the auto-reset when uploading from the IDE)?
On the hardware side you simply wire a series .1ufd cap between the DTR pin and the Arduino reset pin. On the software side it depends on the PC's host software application programs interface to the OS driver for the FTDI device on how you actually toggle the DTR signal. It also appears on most OS just connecting to the FTDI USB comm port causes the DTR assertion and that causes a board reset on the arduino.
Lefty
I found I also had to put a 10k resistor from pin 1 to ground with the .1uF cap to the DTR pin, and it worked everytime. Some of those USB TTL devices pull the DTR low, but never let it go high again.
So by using a capacitor you allow it to be pulled low initially, but then it goes high again as the DC can't get through. Pretty new to this but I imagine the 10k resistor is what makes it appear as if it is going back high.