SMODE powerred from a USB

Question

RCM6700 board, SMODE controls program from USB as per the dev board, FT232 pin 2 (DTR) connected to RESET_IN.
In my final board can I tie (via resistor, switch or relay) the +5VCC power from the USB connector to the SMODE pin. The desired effect is for the Rabbit to enter program mode as the USB is connected without having to move a jumper as done on the dev board?

Will I have to reset the board manually after connecting the USB.?

Answer 1

I guess you could try modifying your development board to test that, but keep in mind that the Rabbit I/O pins are 3V3 and not 5V. You'll want to use a gate to control the board's Vcc based on presence of the USB cable. Additionally, if you go this route, you won't be able to use the FT232 interface as a serial console (serial port A) when your program is in "run mode".

You'll want to test it out, but I think you'll need to manually reset the board when you disconnect the USB cable. My recollection is that the Rabbit only checks the SMODE pins at startup.