Hi Antoine, I was looking for the firmware myself. No luck so far. Have you found it? The problem I am having is with the GPS communication. I don't have the original WK GPS and am trying to get a Beitian BN-880 to work with the WK-CTL01-D. So far I have tried all the combinations of the TX/RX and I2C D/C lines and the GPS won't show in the sensor view with original Devo transmitters and the Deviation transmitters. I am beginning to suspect that the firmware in this module does not support GPS, only voltage and temperature, since it was shipped for the UFO-MX400 which does not have a GPS module. So if you had any luck in finding a firmware for the CTL01, it could be the one that has the GPS communication enabled. I will keep looking myself and post the results here if I find any. Tempted to get the original WK GPS, just to prove my logic, but it is expensive and rare and runs about USD$80.
So good luck with your search. btw there is a microswitch on the CTL01 that says 'Clean' which might be the equivalent of the binding reset plug on regular transmitters. If you are still having problems try pressing it during power-up.
Cheers.
