All the LCD lines are output only. The PIC comms line is, I think, unidirectional. Button presses are actually encoded as IR signals, and sent down the CIR RX line. The IRDA RX line is an input, the TX is an output. The LCD Bias line is a digital signal, basically a square wave drive. The DCIN line is fed straight from the conditioned external DC power. All signals are 3V.

pca