Add support for Car Remotes

[eshaz]

Add support for multiple car remotes / keyfobs.

See merbanan/rtl_433_tests#462 for decode samples and documentation.

Manufacturer / Model:

• Astroflex
  • Astrostart 2000
  • Astrostart 3000
• Alps
  • FWB1U545
• Audiovox
  • PRO-OE3B, AVX01BT3CL3 (FCC ID BGAOE3B)
• Code Alarm
  • FRDPC2002
• Compustar
  • 1WG3R-SH
  • 1WAMR-1900
• Continental
  • KR5V2X
• Chrysler
  • 56008761
  • 56008762 (FCC ID GQ43VT7T)
  • 04686366
  • 56021903AA
• General Motors
  • ABO1502T
• Microchip
  • HCS361
• Nidec
  • OUCG8D-344H-A
• Nutek
  • ATCD-1
  • APS99BT3BCF4, ATCH (FCC ID ELVATCD)
  • AVX1BS4, AVX-1BS4 (FCC ID ELVATCC)
  • A1BTX (FCC ID ELVATFE)
  • 105BP (FCC ID ELVATJA)
• Siemens
  • 5WY72XX
• Unknown
  • 6SC2

Resolves #2754

[zuckschwerdt]

Thanks! Simple decoders without value processing or checksums are best implemented as flex decoder confs, for examples see https://github.com/merbanan/rtl_433/tree/master/conf

For PWM Short and long need to be different, is your code that a typo?

E.g.

decoder {
    name=Audiovox-car-remote,
    modulation=OOK_PWM,
    short=550,
    long=1000,
    reset=1300,
    bits=37,
    get=
    get=@0:{16}:id,
    get=@16:{16}:code,
    get=@17:{1}:chk,
    get=@18:{4}:flags,
}

You can just add a documented conf to this PR.

[eshaz]

Thanks! Simple decoders without value processing or checksums are best implemented as flex decoder confs, for examples see https://github.com/merbanan/rtl_433/tree/master/conf

I have a few devices on the 433Mhz frequency already and just using the flex decoder was causing false positives. I added a few sanity checks here that removed the false positives:

rtl_433/src/devices/audiovox_car_remote.c

Lines 69 to 71 in d743eb6

	if (id == 0 || code == 0 || button == 0 || id == 0xffff || code == 0xffff) {
	return DECODE_FAIL_SANITY;
	}

[eshaz]

I've finished decoding / reverse engineering all of the keyfobs I have as mentioned in #2754. Let me know if there's any formatting or changes needed.

I also have this PR open: merbanan/rtl_433_tests#462 that documents and adds some sample data for these devices.