Documentation/media/v4l-drivers/radiotrack.rst

   1 The Radiotrack radio driver
   2 ===========================
   3
   4 Author: Stephen M. Benoit <benoits@servicepro.com>
   5
   6 Date:  Dec 14, 1996
   7
   8 ACKNOWLEDGMENTS
   9 ----------------
  10
  11 This document was made based on 'C' code for Linux from Gideon le Grange
  12 (legrang@active.co.za or legrang@cs.sun.ac.za) in 1994, and elaborations from
  13 Frans Brinkman (brinkman@esd.nl) in 1996.  The results reported here are from
  14 experiments that the author performed on his own setup, so your mileage may
  15 vary... I make no guarantees, claims or warranties to the suitability or
  16 validity of this information.  No other documentation on the AIMS
  17 Lab (http://www.aimslab.com/) RadioTrack card was made available to the
  18 author.  This document is offered in the hopes that it might help users who
  19 want to use the RadioTrack card in an environment other than MS Windows.
  20
  21 WHY THIS DOCUMENT?
  22 ------------------
  23
  24 I have a RadioTrack card from back when I ran an MS-Windows platform.  After
  25 converting to Linux, I found Gideon le Grange's command-line software for
  26 running the card, and found that it was good!  Frans Brinkman made a
  27 comfortable X-windows interface, and added a scanning feature.  For hack
  28 value, I wanted to see if the tuner could be tuned beyond the usual FM radio
  29 broadcast band, so I could pick up the audio carriers from North American
  30 broadcast TV channels, situated just below and above the 87.0-109.0 MHz range.
  31 I did not get much success, but I learned about programming ioports under
  32 Linux and gained some insights about the hardware design used for the card.
  33
  34 So, without further delay, here are the details.
  35
  36
  37 PHYSICAL DESCRIPTION
  38 --------------------
  39
  40 The RadioTrack card is an ISA 8-bit FM radio card.  The radio frequency (RF)
  41 input is simply an antenna lead, and the output is a power audio signal
  42 available through a miniature phone plug.  Its RF frequencies of operation are
  43 more or less limited from 87.0 to 109.0 MHz (the commercial FM broadcast
  44 band).  Although the registers can be programmed to request frequencies beyond
  45 these limits, experiments did not give promising results.  The variable
  46 frequency oscillator (VFO) that demodulates the intermediate frequency (IF)
  47 signal probably has a small range of useful frequencies, and wraps around or
  48 gets clipped beyond the limits mentioned above.
  49
  50
  51 CONTROLLING THE CARD WITH IOPORT
  52 --------------------------------
  53
  54 The RadioTrack (base) ioport is configurable for 0x30c or 0x20c.  Only one
  55 ioport seems to be involved.  The ioport decoding circuitry must be pretty
  56 simple, as individual ioport bits are directly matched to specific functions
  57 (or blocks) of the radio card.  This way, many functions can be changed in
  58 parallel with one write to the ioport.  The only feedback available through
  59 the ioports appears to be the "Stereo Detect" bit.
  60
  61 The bits of the ioport are arranged as follows:
  62
  63 .. code-block:: none
  64
  65         MSb                                                         LSb
  66         +------+------+------+--------+--------+-------+---------+--------+
  67         | VolA | VolB | ???? | Stereo | Radio  | TuneA | TuneB   | Tune   |
  68         |  (+) |  (-) |      | Detect | Audio  | (bit) | (latch) | Update |
  69         |      |      |      | Enable | Enable |       |         | Enable |
  70         +------+------+------+--------+--------+-------+---------+--------+
  71
  72
  73 ====  ====  =================================
  74 VolA  VolB  Description
  75 ====  ====  =================================
  76 0        0  audio mute
  77 0        1  volume +    (some delay required)
  78 1        0  volume -    (some delay required)
  79 1        1  stay at present volume
  80 ====  ====  =================================
  81
  82 ====================    ===========
  83 Stereo Detect Enable    Description
  84 ====================    ===========
  85 0                       No Detect
  86 1                       Detect
  87 ====================    ===========
  88
  89 Results available by reading ioport >60 msec after last port write.
  90
  91   0xff ==> no stereo detected,  0xfd ==> stereo detected.
  92
  93 =============================   =============================
  94 Radio to Audio (path) Enable    Description
  95 =============================   =============================
  96 0                               Disable path (silence)
  97 1                               Enable path  (audio produced)
  98 =============================   =============================
  99
 100 =====  =====  ==================
 101 TuneA  TuneB  Description
 102 =====  =====  ==================
 103 0       0     "zero" bit phase 1
 104 0       1     "zero" bit phase 2
 105 1       0     "one" bit phase 1
 106 1       1     "one" bit phase 2
 107 =====  =====  ==================
 108
 109
 110 24-bit code, where bits = (freq*40) + 10486188.
 111 The Most Significant 11 bits must be 1010 xxxx 0x0 to be valid.
 112 The bits are shifted in LSb first.
 113
 114 ==================      ===========================
 115 Tune Update Enable      Description
 116 ==================      ===========================
 117 0                       Tuner held constant
 118 1                       Tuner updating in progress
 119 ==================      ===========================
 120
 121
 122 PROGRAMMING EXAMPLES
 123 --------------------
 124
 125 .. code-block:: none
 126
 127         Default:        BASE <-- 0xc8  (current volume, no stereo detect,
 128                                         radio enable, tuner adjust disable)
 129
 130         Card Off:       BASE <-- 0x00  (audio mute, no stereo detect,
 131                                         radio disable, tuner adjust disable)
 132
 133         Card On:        BASE <-- 0x00  (see "Card Off", clears any unfinished business)
 134                         BASE <-- 0xc8  (see "Default")
 135
 136         Volume Down:    BASE <-- 0x48  (volume down, no stereo detect,
 137                                         radio enable, tuner adjust disable)
 138                         wait 10 msec
 139                         BASE <-- 0xc8  (see "Default")
 140
 141         Volume Up:      BASE <-- 0x88  (volume up, no stereo detect,
 142                                         radio enable, tuner adjust disable)
 143                         wait 10 msec
 144                         BASE <-- 0xc8  (see "Default")
 145
 146         Check Stereo:   BASE <-- 0xd8  (current volume, stereo detect,
 147                                         radio enable, tuner adjust disable)
 148                         wait 100 msec
 149                         x <-- BASE     (read ioport)
 150                         BASE <-- 0xc8  (see "Default")
 151
 152                         x=0xff ==> "not stereo", x=0xfd ==> "stereo detected"
 153
 154         Set Frequency:  code = (freq*40) + 10486188
 155                         foreach of the 24 bits in code,
 156                         (from Least to Most Significant):
 157                         to write a "zero" bit,
 158                         BASE <-- 0x01  (audio mute, no stereo detect, radio
 159                                         disable, "zero" bit phase 1, tuner adjust)
 160                         BASE <-- 0x03  (audio mute, no stereo detect, radio
 161                                         disable, "zero" bit phase 2, tuner adjust)
 162                         to write a "one" bit,
 163                         BASE <-- 0x05  (audio mute, no stereo detect, radio
 164                                         disable, "one" bit phase 1, tuner adjust)
 165                         BASE <-- 0x07  (audio mute, no stereo detect, radio
 166                                         disable, "one" bit phase 2, tuner adjust)