Programming via Bluetooth: Desperately trying to Auto-Reset :(

So, to program the Arduino via Bluetooth, you need to reset the Arduino JUST (like...within 500ms) before the hex data flows from the BT module into the TX and RX pins of the Arduino. How can I detect when data is JUST about to arrive? The Bluetooth module I'm using (RN-42) has no DTR pin on the breakout board I'm using.

Thanks!

Try RTS if available, but, I am in doubt the BT will do. I am coping with that as well (btm400_6b) and I cannot get RTS working. Do it manualy then… =(

The BT module does have CTS and RTS pins. Will RTS go high/low momentarily right before data is going to be sent?

Anyone?