167 lines
6.1 KiB
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167 lines
6.1 KiB
ReStructuredText
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The Radiotrack radio driver
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===========================
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Author: Stephen M. Benoit <benoits@servicepro.com>
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Date: Dec 14, 1996
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ACKNOWLEDGMENTS
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----------------
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This document was made based on 'C' code for Linux from Gideon le Grange
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(legrang@active.co.za or legrang@cs.sun.ac.za) in 1994, and elaborations from
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Frans Brinkman (brinkman@esd.nl) in 1996. The results reported here are from
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experiments that the author performed on his own setup, so your mileage may
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vary... I make no guarantees, claims or warranties to the suitability or
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validity of this information. No other documentation on the AIMS
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Lab (http://www.aimslab.com/) RadioTrack card was made available to the
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author. This document is offered in the hopes that it might help users who
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want to use the RadioTrack card in an environment other than MS Windows.
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WHY THIS DOCUMENT?
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------------------
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I have a RadioTrack card from back when I ran an MS-Windows platform. After
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converting to Linux, I found Gideon le Grange's command-line software for
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running the card, and found that it was good! Frans Brinkman made a
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comfortable X-windows interface, and added a scanning feature. For hack
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value, I wanted to see if the tuner could be tuned beyond the usual FM radio
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broadcast band, so I could pick up the audio carriers from North American
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broadcast TV channels, situated just below and above the 87.0-109.0 MHz range.
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I did not get much success, but I learned about programming ioports under
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Linux and gained some insights about the hardware design used for the card.
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So, without further delay, here are the details.
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PHYSICAL DESCRIPTION
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--------------------
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The RadioTrack card is an ISA 8-bit FM radio card. The radio frequency (RF)
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input is simply an antenna lead, and the output is a power audio signal
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available through a miniature phone plug. Its RF frequencies of operation are
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more or less limited from 87.0 to 109.0 MHz (the commercial FM broadcast
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band). Although the registers can be programmed to request frequencies beyond
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these limits, experiments did not give promising results. The variable
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frequency oscillator (VFO) that demodulates the intermediate frequency (IF)
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signal probably has a small range of useful frequencies, and wraps around or
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gets clipped beyond the limits mentioned above.
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CONTROLLING THE CARD WITH IOPORT
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--------------------------------
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The RadioTrack (base) ioport is configurable for 0x30c or 0x20c. Only one
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ioport seems to be involved. The ioport decoding circuitry must be pretty
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simple, as individual ioport bits are directly matched to specific functions
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(or blocks) of the radio card. This way, many functions can be changed in
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parallel with one write to the ioport. The only feedback available through
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the ioports appears to be the "Stereo Detect" bit.
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The bits of the ioport are arranged as follows:
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.. code-block:: none
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MSb LSb
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+------+------+------+--------+--------+-------+---------+--------+
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| VolA | VolB | ???? | Stereo | Radio | TuneA | TuneB | Tune |
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| (+) | (-) | | Detect | Audio | (bit) | (latch) | Update |
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| | | | Enable | Enable | | | Enable |
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+------+------+------+--------+--------+-------+---------+--------+
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==== ==== =================================
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VolA VolB Description
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==== ==== =================================
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0 0 audio mute
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0 1 volume + (some delay required)
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1 0 volume - (some delay required)
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1 1 stay at present volume
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==== ==== =================================
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==================== ===========
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Stereo Detect Enable Description
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==================== ===========
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0 No Detect
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1 Detect
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==================== ===========
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Results available by reading ioport >60 msec after last port write.
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0xff ==> no stereo detected, 0xfd ==> stereo detected.
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============================= =============================
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Radio to Audio (path) Enable Description
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============================= =============================
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0 Disable path (silence)
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1 Enable path (audio produced)
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============================= =============================
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===== ===== ==================
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TuneA TuneB Description
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===== ===== ==================
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0 0 "zero" bit phase 1
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0 1 "zero" bit phase 2
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1 0 "one" bit phase 1
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1 1 "one" bit phase 2
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===== ===== ==================
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24-bit code, where bits = (freq*40) + 10486188.
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The Most Significant 11 bits must be 1010 xxxx 0x0 to be valid.
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The bits are shifted in LSb first.
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================== ===========================
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Tune Update Enable Description
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================== ===========================
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0 Tuner held constant
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1 Tuner updating in progress
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================== ===========================
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PROGRAMMING EXAMPLES
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--------------------
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.. code-block:: none
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Default: BASE <-- 0xc8 (current volume, no stereo detect,
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radio enable, tuner adjust disable)
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Card Off: BASE <-- 0x00 (audio mute, no stereo detect,
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radio disable, tuner adjust disable)
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Card On: BASE <-- 0x00 (see "Card Off", clears any unfinished business)
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BASE <-- 0xc8 (see "Default")
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Volume Down: BASE <-- 0x48 (volume down, no stereo detect,
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radio enable, tuner adjust disable)
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wait 10 msec
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BASE <-- 0xc8 (see "Default")
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Volume Up: BASE <-- 0x88 (volume up, no stereo detect,
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radio enable, tuner adjust disable)
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wait 10 msec
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BASE <-- 0xc8 (see "Default")
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Check Stereo: BASE <-- 0xd8 (current volume, stereo detect,
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radio enable, tuner adjust disable)
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wait 100 msec
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x <-- BASE (read ioport)
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BASE <-- 0xc8 (see "Default")
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x=0xff ==> "not stereo", x=0xfd ==> "stereo detected"
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Set Frequency: code = (freq*40) + 10486188
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foreach of the 24 bits in code,
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(from Least to Most Significant):
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to write a "zero" bit,
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BASE <-- 0x01 (audio mute, no stereo detect, radio
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disable, "zero" bit phase 1, tuner adjust)
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BASE <-- 0x03 (audio mute, no stereo detect, radio
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disable, "zero" bit phase 2, tuner adjust)
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to write a "one" bit,
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BASE <-- 0x05 (audio mute, no stereo detect, radio
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disable, "one" bit phase 1, tuner adjust)
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BASE <-- 0x07 (audio mute, no stereo detect, radio
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disable, "one" bit phase 2, tuner adjust)
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