I bought some RF11A04 modules from Aliexpress:
I didn’t find a document explaining how to use it, but I found a video where a guy uses this module in his automation board [1].
The process to make the RF11A04 learn the key codes is very simple:
- Power the module with 3.3V at GND and VCC pins (the PMR LED will turn ON
- Press and hold the KEY button, the LED turns OFF and after 10 seconds it will turn ON again
- When the LED turn ON, Release the KEY button
- Press and Release fast the KEY button, the LED will turn OFF
- Press the each button of the keychain, not the the LED will blink at 2 or 3 times per second
- After you pressed all keys in the keychain the LED will keep turned ON
You can confirm that all keys are recognized correctly pressing them and using a voltmeter (multi-meter) between the GND pin and D0, D1, D2 and D3. When you press the key the corresponding Dx output should change from 0V to 3.3V.