Can someone tell me what the resistors connected between the FT232RL DTR# pin and the ATmega168 reset pin, and the FT232RL RTS# pin and the ATmega168 reset pin on the Arduino Diecimila board are for?
They are labeled "R2 100_NM" and "R3 100_NM", which I assume means they are 100ohm resistors, but when I populate them on my design, the chip FT232RL doesn't respond.
On the actual Arduino board I have, R3 looks like a capacitor, and the spot where I think R2 should be is unpopulated.
Are R2 and R3 resistors? Are they meant to be 100ohm? What is their purpose?
That's for the famous auto reset feature. Actually, those are not resistors, but capacitors! And one of them is not on the PCB. I think the diecimila is only equipped with "R3", to auto reset on DTR.
The actual eagle files have the correct capacitor symbol on DTR#; it looks like the PDF version is older, dating to a time when the team was still experimenting with how the auto-reset was going to work...