I'm working on PC communications for a micro(an RCA 1802) that doesn't have its own uart. My current solution uses an FTDI cable and a big AVR as a bridge but it takes up a lot of room and is generally ugly. The setup is arduino-like in that avrdude can send code to the 1802 thru the avr. The avr resets the 1802 when it is reset by avrdude opening the port.
I was thinking about an FT245RL. I could interface it easily enough directly to the 1802, then code in the 1802 ROM could do the bootloader function but I don't see a way to do an automatic reset when the "port" is opened by the PC. There is a pin called PWREN# which sounds like tells you when the USB is plugged in but not when a port is opened.
PWREN# goes low after the device is configured by USB, then high during USB suspend. Can be used to control power to external logic P-Channel logic level MOSFET switch. Enable the interface pull-down option when using the PWREN# pin in this way. Should be pulled to VCCIO with 10k? resistor.
Anybody have any direct experience with behaviour of PWREN or any other ideas?