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Diffstat (limited to 'Documentation/media')
-rw-r--r-- | Documentation/media/v4l-drivers/cx88.rst | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/Documentation/media/v4l-drivers/cx88.rst b/Documentation/media/v4l-drivers/cx88.rst index c89dbfa5f9d6..97865007f51f 100644 --- a/Documentation/media/v4l-drivers/cx88.rst +++ b/Documentation/media/v4l-drivers/cx88.rst @@ -98,3 +98,65 @@ MO_OUTPUT_FORMAT (0x310164) 0x47 is the sync byte for MPEG-2 transport stream packets. Datasheet incorrectly states to use 47 decimal. 188 is the length. All DVB compliant frontends output packets with this start code. + +Hauppauge WinTV cx88 IR information +----------------------------------- + +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 +- 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. + +Additional info +~~~~~~~~~~~~~~~ + +This data sheet (google search) seems to have a lovely description of the +RC5 basics: +http://www.atmel.com/dyn/resources/prod_documents/doc2817.pdf + +This document has more data: +http://www.nenya.be/beor/electronics/rc5.htm + +This document has a how to decode a bi-phase data stream: +http://www.ee.washington.edu/circuit_archive/text/ir_decode.txt + +This document has still more info: +http://www.xs4all.nl/~sbp/knowledge/ir/rc5.htm |