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Diffstat (limited to 'kernel/Documentation/video4linux/hauppauge-wintv-cx88-ir.txt')
| -rw-r--r-- | kernel/Documentation/video4linux/hauppauge-wintv-cx88-ir.txt | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/kernel/Documentation/video4linux/hauppauge-wintv-cx88-ir.txt b/kernel/Documentation/video4linux/hauppauge-wintv-cx88-ir.txt new file mode 100644 index 000000000..a2fd363c4 --- /dev/null +++ b/kernel/Documentation/video4linux/hauppauge-wintv-cx88-ir.txt @@ -0,0 +1,54 @@ +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 + |