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- 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
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