The controls for the mux are GPIO [0,1] for source, and GPIO 2 for muting. GPIO0 GPIO1 0 0 TV Audio 1 0 FM radio 0 1 Line-In 1 1 Mono tuner bypass or CD passthru (tuner specific) GPIO 16(i believe) is tied to the IR port (if present). ------------------------------------------------------------------------------------ >From the data sheet: Register 24'h20004 PCI Interrupt Status bit [18] IR_SMP_INT Set when 32 input samples have been collected over gpio[16] pin into GP_SAMPLE register. What's missing from the data sheet: Setup 4KHz sampling rate (roughly 2x oversampled; good enough for our RC5 compat remote) set register 0x35C050 to 0xa80a80 enable sampling set register 0x35C054 to 0x5 Of course, enable the IRQ bit 18 in the interrupt mask register .(and provide for a handler) GP_SAMPLE register is at 0x35C058 Bits are then right shifted into the GP_SAMPLE register at the specified rate; you get an interrupt when a full DWORD is received. You need to recover the actual RC5 bits out of the (oversampled) IR sensor bits. (Hint: look for the 0/1and 1/0 crossings of the RC5 bi-phase data) An actual raw RC5 code will span 2-3 DWORDS, depending on the actual alignment. I'm pretty sure when no IR signal is present the receiver is always in a marking state(1); but stray light, etc can cause intermittent noise values as well. Remember, this is a free running sample of the IR receiver state over time, so don't assume any sample starts at any particular place. http://www.atmel.com/dyn/resources/prod_documents/doc2817.pdf This data sheet (google search) seems to have a lovely description of the RC5 basics http://www.nenya.be/beor/electronics/rc5.htm and more data http://www.ee.washington.edu/circuit_archive/text/ir_decode.txt and even a reference to how to decode a bi-phase data stream. http://www.xs4all.nl/~sbp/knowledge/ir/rc5.htm still more info