Hi All:
Need some advice.
Does the RN42 contain a processor core such as a 16f or 18F?
Or does all processing have to be done on a separate MPU and then transmitted via local SPI/UART for RF retransmission by the RN42.
Never really used it but seems like you will need a micro to tell RN42 to read the GPIO and then you do something based on results which may include relaying that info over Bluetooth...
You can create some simple 9600 bps code for a PIC12F (8pin/6pin) to talk to the RN42 and do the work... adds about $1 to total cost This way you can simply tell the PIC to READ GPIO from RN42 and TRANSMIT it over BLUETOOTH in a loop...