0001 .. SPDX-License-Identifier: GPL-2.0
0002
0003 The cx88 driver
0004 ===============
0005
0006 Author: Gerd Hoffmann
0007
0008 Documentation missing at the cx88 datasheet
0009 -------------------------------------------
0010
0011 MO_OUTPUT_FORMAT (0x310164)
0012
0013 .. code-block:: none
0014
0015 Previous default from DScaler: 0x1c1f0008
0016 Digit 8: 31-28
0017 28: PREVREMOD = 1
0018
0019 Digit 7: 27-24 (0xc = 12 = b1100 )
0020 27: COMBALT = 1
0021 26: PAL_INV_PHASE
0022 (DScaler apparently set this to 1, resulted in sucky picture)
0023
0024 Digits 6,5: 23-16
0025 25-16: COMB_RANGE = 0x1f [default] (9 bits -> max 512)
0026
0027 Digit 4: 15-12
0028 15: DISIFX = 0
0029 14: INVCBF = 0
0030 13: DISADAPT = 0
0031 12: NARROWADAPT = 0
0032
0033 Digit 3: 11-8
0034 11: FORCE2H
0035 10: FORCEREMD
0036 9: NCHROMAEN
0037 8: NREMODEN
0038
0039 Digit 2: 7-4
0040 7-6: YCORE
0041 5-4: CCORE
0042
0043 Digit 1: 3-0
0044 3: RANGE = 1
0045 2: HACTEXT
0046 1: HSFMT
0047
0048 0x47 is the sync byte for MPEG-2 transport stream packets.
0049 Datasheet incorrectly states to use 47 decimal. 188 is the length.
0050 All DVB compliant frontends output packets with this start code.
0051
0052 Hauppauge WinTV cx88 IR information
0053 -----------------------------------
0054
0055 The controls for the mux are GPIO [0,1] for source, and GPIO 2 for muting.
0056
0057 ====== ======== =================================================
0058 GPIO0 GPIO1
0059 ====== ======== =================================================
0060 0 0 TV Audio
0061 1 0 FM radio
0062 0 1 Line-In
0063 1 1 Mono tuner bypass or CD passthru (tuner specific)
0064 ====== ======== =================================================
0065
0066 GPIO 16(I believe) is tied to the IR port (if present).
0067
0068
0069 From the data sheet:
0070
0071 - Register 24'h20004 PCI Interrupt Status
0072
0073 - bit [18] IR_SMP_INT Set when 32 input samples have been collected over
0074 - gpio[16] pin into GP_SAMPLE register.
0075
0076 What's missing from the data sheet:
0077
0078 - Setup 4KHz sampling rate (roughly 2x oversampled; good enough for our RC5
0079 compat remote)
0080 - set register 0x35C050 to 0xa80a80
0081 - enable sampling
0082 - set register 0x35C054 to 0x5
0083 - enable the IRQ bit 18 in the interrupt mask register (and
0084 provide for a handler)
0085
0086 GP_SAMPLE register is at 0x35C058
0087
0088 Bits are then right shifted into the GP_SAMPLE register at the specified
0089 rate; you get an interrupt when a full DWORD is received.
0090 You need to recover the actual RC5 bits out of the (oversampled) IR sensor
0091 bits. (Hint: look for the 0/1and 1/0 crossings of the RC5 bi-phase data) An
0092 actual raw RC5 code will span 2-3 DWORDS, depending on the actual alignment.
0093
0094 I'm pretty sure when no IR signal is present the receiver is always in a
0095 marking state(1); but stray light, etc can cause intermittent noise values
0096 as well. Remember, this is a free running sample of the IR receiver state
0097 over time, so don't assume any sample starts at any particular place.
0098
0099 Additional info
0100 ~~~~~~~~~~~~~~~
0101
0102 This data sheet (google search) seems to have a lovely description of the
0103 RC5 basics:
0104 http://www.atmel.com/dyn/resources/prod_documents/doc2817.pdf
0105
0106 This document has more data:
0107 http://www.nenya.be/beor/electronics/rc5.htm
0108
0109 This document has a how to decode a bi-phase data stream:
0110 http://www.ee.washington.edu/circuit_archive/text/ir_decode.txt
0111
0112 This document has still more info:
0113 http://www.xs4all.nl/~sbp/knowledge/ir/rc5.htm
