[InnovationFirst]

The likely cause of both of your problems with the TTL serial port is because the RX pin is configured as an output, instead of an input. We will be releasing new default code shortly which will correctly configure it for you. Until then, you must manually configure the Rx as an input and the Tx as an output. Microchip's Open2USART function does not do this for you.

Apparently we already do this in the Mini RC initialization, which is why your sensorpack worked on the Mini RC, Gene. But on the FRC they are both set as outputs, which is why you are seeing high impedance on the Rx line, and then getting that crosstalk noise.

To fix the problem for now, just add these two lines to your initialization code:
TRISGbits.TRISG1 = 0;
TRISGbits.TRISG2 = 1;

In the upcoming default code change, this will be done automatically.

Regards,
The Firmware Team
Innovation First, Inc.