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